June 2025 2025 Air Monitoring Network Plan Maricopa County Air Quality Department Air Monitoring Division Table of Contents 2025 AIR MONITORING NETWORK PLAN 1 LIST OF TABLES .................................................................................................................................. 3 LIST OF FIGURES ................................................................................................................................. 4 ABSTRACT 1 NETWORK MODIFICATIONS AND SITE UPDATES ..................................................................................... 2 Summary of Past Network Modifications and Site Updates ....................................................... 2 Proposed Network Modifications and Site Updates .................................................................... 2 INTRODUCTION 5 CLEAN AIR ACT AND CRITERIA POLLUTANTS ........................................................................................ 9 THE NATIONAL AMBIENT AIR QUALITY STANDARDS ............................................................................. 9 FORECASTING AND REPORTING AIR QUALITY CONDITIONS .................................................................... 11 Air Quality Forecasting .................................................................................................................. 11 The EPA Air Quality Index and NowCast ..................................................................................... 11 The Maricopa County Interactive Air Quality Map ..................................................................... 13 AIR MONITORING STRATEGIES AND SURVEILLANCE SYSTEM DESIGN 15 OVERVIEW OF AIR MONITORING REQUIREMENTS AND SYSTEM DESIGN ................................................... 15 Basic Air Monitoring Objectives ................................................................................................... 16 Monitor Types ................................................................................................................................. 16 Site Types ....................................................................................................................................... 17 Monitoring Scales (Spatial Scales of Representativeness) ...................................................... 18 Overview of the Air Monitoring Sites ........................................................................................... 19 SUMMARY OF NETWORK RESULTS AND REQUIRED INFORMATION 20 Determining Data Quality and Acceptability ............................................................................... 20 Data Completeness ........................................................................................................................ 20 SUMMARY OF 2024 CRITERIA POLLUTANT DATA 22 CARBON MONOXIDE (CO) ................................................................................................................... 22 NITROGEN DIOXIDE (NO2) ................................................................................................................... 24 OZONE (O3) ........................................................................................................................................ 26 PARTICULATE MATTER ≤10 MICROMETERS (PM10) ............................................................................. 30 PARTICULATE MATTER ≤2.5 MICROMETERS (PM2.5) ........................................................................... 34 SULFUR DIOXIDE (SO2) ....................................................................................................................... 39 SUMMARY OF 2024 CRITERIA POLLUTANT NAAQS STATUS 41 2024 O3 EXCEEDANCE, VIOLATION, AND EXCEPTIONAL EVENT INFORMATION ........................................ 42 O3 NAAQS Exceedances ................................................................................................................ 42 Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan ii O3 Exceptional Events and Status of EPA Concurrence ............................................................ 42 2024 PM10 EXCEEDANCE, VIOLATION, AND EXCEPTIONAL EVENT INFORMATION ................................... 46 PM10 NAAQS Exceedances ........................................................................................................... 46 2024 PM2.5 EXCEEDANCE, VIOLATION, AND EXCEPTIONAL EVENT INFORMATION ................................... 49 PM2.5 Annual NAAQS Exceedance and Violation Status ........................................................... 49 PM2.5 24-Hour NAAQS Exceedance and Violation Status ......................................................... 49 PM2.5 Exceptional Events and Status of EPA Concurrence ....................................................... 50 SHARED AIR MONITORING RESPONSIBILITIES ....................................................................................... 50 Information Regarding Additional Air Monitoring within Maricopa County ............................ 50 REFERENCES 51 APPENDIX I - AIR MONITORING DATA BY SITE 52 APPENDIX II - PUBLIC NOTICE AND COMMENT INFORMATION 134 APPENDIX III – GLOSSARY 138 List of Tables Table 1 Summary of Past Network Modifications and Site Updates ...................................... 2 Table 2 Projects Planned for 2025 ........................................................................................................ 3 Table 3 MCAQD Air Monitoring Instruments by Site ..................................................................... 8 Table 4 National Ambient Air Quality Standards ........................................................................... 10 Table 5 Basic SLAMS Air Monitoring Objectives .......................................................................... 16 Table 6 Monitor Types .............................................................................................................................. 17 Table 7 Spatial Scales of Representativeness ............................................................................... 18 Table 8 2024 Criteria Pollutant Data Completeness for SLAMS ............................................ 21 Table 9 2024 CO Average Data Summary ........................................................................................ 23 Table 10 2024 CO Monitor Requirements ........................................................................................ 23 Table 11 2024 NO2 1-hour Data Summary ....................................................................................... 25 Table 12 2024 NO2 Monitor Requirements ...................................................................................... 25 Table 13 2024 O3 Eight-hour Average Summary .......................................................................... 28 Table 14 2024 O3 Monitor Requirements ......................................................................................... 29 Table 15 2024 PM10 24-Hour Average Summary ......................................................................... 32 Table 16 2024 PM10 Monitor Requirements.................................................................................... 33 Table 17 2024 PM2.5 24-Hour and Annual Averages ................................................................... 35 Table 18 PM2.5 3-Year Annual Averages .......................................................................................... 36 Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan iii Table 19 PM2.5 3-Year 24-Hour Averages of the 98th Percentile ......................................... 37 Table 20 2024 PM2.5 Data Required by EPA .................................................................................... 38 Table 21 2024 SO2 Data Summary ...................................................................................................... 40 Table 22 2024 SO2 Monitor Requirements ...................................................................................... 40 Table 23 2024 NAAQS Exceedances and Violation Summary ................................................. 41 Table 24 2024 Violations of the PM10 24-Hour NAAQS Including EE Data ........................ 47 Table 25 2024 Violations of the PM10 NAAQS Excluding Data Flagged as an EE ............ 48 Table 26 2025 Open Forum Meeting Attendees .......................................................................... 137 List of Figures Figure 1 2024 Maricopa County Air Monitoring Sites ................................................................... 7 Figure 2 The Air Quality Index ............................................................................................................... 12 Figure 3 AirNow Web Maps .................................................................................................................... 13 Figure 4 MCAQD Air Quality Status Map........................................................................................... 14 Figure 5 2024 CO Monitoring Sites ..................................................................................................... 22 Figure 6 2024 NO2 Monitoring Sites ................................................................................................... 24 Figure 7 2024 O3 Monitoring Sites ...................................................................................................... 27 Figure 8 2024 PM10 Monitoring Sites................................................................................................. 30 Figure 9 2024 PM2.5 Monitoring Sites ................................................................................................ 34 Figure 10 2024 SO2 Monitoring Sites ................................................................................................. 39 Figure 11 Ozone Exceedance Days...................................................................................................... 43 Figure 12 2024 O3 NAAQS Violations by Site Including Exceptional Events ..................... 44 Figure 13 2024 O3 NAAQS Violations by Site Excluding Exceptional Events .................... 45 Figure 14 2024 PM10 Exceedance Days ............................................................................................ 46 Figure 15 2024 PM2.5 Exceedance Days............................................................................................ 49 Figure 16 Public Comment Period Announcement .................................................................... 135 Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan iv ABSTRACT In 2024, the Maricopa County Air Quality Department (MCAQD) Air Monitoring Division successfully operated a robust air quality surveillance system that monitored for regulated ambient air pollutants as per 40 CFR Parts 50 and 58. The air monitoring data produced are intended for regulatory compliance determinations of criteria air pollutants. Unless otherwise noted, each monitor meets the requirements of 40 CFR Part 58 – Subpart G - Appendices A, B, C, D, and E, where applicable. MCAQD strives to provide the most reliable and relevant air monitoring data to the public. High-quality data are a cornerstone of developing and implementing effective State Implementation Plans (SIPs), Exceptional Event (EE) packages, and operating permits for new and existing sources, for the protection of human health and the environment. This Air Monitoring Network Plan provides information regarding the air monitoring surveillance system operating within Maricopa County, covers changes made to the air monitoring network in 2024, and discusses network changes planned for 2025. Please refer to Appendix III for the glossary of terms and acronyms. Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 1 Network Modifications and Site Updates Summary of Past Network Modifications and Site Updates Table 1 Summary of Past Network Modifications and Site Updates Date Site Monitor/ Type Description 2024 Infrastructure Data Servers Transitioned from cloud-hosted data servers to on-premises data hosting. This change allowed us to create a production environment to house our continuous monitoring data and a development environment which allows us to develop and test improvements to our data collection system. 2024 West Phoenix (04-013-0019) O3, NO2, CO Removed all remaining Thermo Scientific gaseous analyzers from the Air Monitoring Network and replaced them with Teledyne analyzers. The MCAQD gaseous SLAMS network is now fully Teledyne units. 2024 Cave Creek (04013-4008) O3 Relocated the Cave Creek monitoring shelter approximately 70 feet to the south of the previous location. The new shelter is a dedicated Air Quality shelter with more effective climate control. Proposed Network Modifications and Site Updates MCAQD does not anticipate any significant interruptions to monitoring operations in 2025 and plans on continuously updating existing sites and improving site safety and security. Improvements to power supplies or communication systems will occur as needed. Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 2 Table 2 Projects Planned for 2025 Planned Date Site Monitor/ Type Description 2025 Falcon Field (04-0131010) Ozone, Wind Speed, Wind Direction Searching for a new site location to improve access and sample line configuration, and to allow for a wind tower to be secured. Due to safety concerns at the current site location, MCAQD discontinued monitoring for wind speed and wind direction in March of 2021. 2025 Scottsdale (04-0133003) Ozone, PM10 Contacted the City of Scottsdale to obtain permission to place a shelter at the site. This will allow for better placement of the ozone sample cane and PM10 sampler. The move is planned as a safety precaution to prevent technicians from having to access the roof of a building. 2025 Buckeye (04-0134011) Ground Level Ozone Research (GLOR) Project MCAQD is providing support to other government and research entities with the Ground Level Ozone Research (GLOR) Project. MCAQD’s involvement in this study is to provide access to secured monitoring sites for our partners to setup instrumentation to study the formation pathways of Ozone on a local and national scale. Instrumentation, QA, and QC for this project will be primarily conducted by our partners with support from MCAQD where needed. Details about project operations can be found in the Arizona Department of Environmental Quality’s (ADEQ) project QAPP. Durango Complex (04-0139812) Fountain Hills (04-0139704) Higley (04-0134006) 2025 Durango Complex Special To further support the GLOR project Purpose mentioned in the above row of this table, Monitor for O3 MCAQD will be setting up a Special Purpose O3 monitor at the Durango Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 3 (04-0139812) Jan 2026 Durango Complex (04-0139812) Complex site to provide further data for this research study. Temporary Site Move The lot that the Durango Complex monitor is situated on is owned and maintained by Maricopa County’s Department of Transportation. The lot is scheduled to be entirely resurfaced in January of 2026. As a result, instrumentation will be loaded onto a mobile trailer and relocated approximately 100 feet for continued operation during the resurfacing project. Instrumentation will be reinstalled at the current location once the project is completed. Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 4 Introduction This Annual Monitoring Network Plan (AMNP) addresses the United States Environmental Protection Agency’s (U.S. EPA) requirements for operating the surveillance system as per 40 CFR Part 58 - Ambient Air Quality Surveillance. As per 40 CFR Part 58, Subpart B §58.10(a)(1), the EPA requires each air monitoring organization operating within the U.S. and its territories to develop and submit an AMNP annually by July 1st, following a 30-day public comment period. Each year, MCAQD solicits comments from the public during the public comment period and holds an open forum public meeting. As needed, MCAQD amends the final draft based on any comments received. The final AMNP is submitted to EPA Region 9 for review and approval. The EPA Region 9 Administrator, or their representative, must approve any requests for network changes and waivers. EPA Region 9 completes the review process within 120 days. MCAQD will post the final AMNP on the MCAQD Air Monitoring website. In addition to the annual data certification process, the network plan helps MCAQD continuously review, assess, and improve how well the air monitoring surveillance system, or network, is performing. Data certification for 2024 was submitted to EPA Region 9 on April 28, 2025. The design and performance of the ambient air monitoring network and data certification process are covered by the regulatory requirements found in:  40 CFR Part 58 – Ambient Air Quality Surveillance: Subpart A (General Provisions), Subpart B (Monitoring Network), Subpart C (Special Purpose Monitors (SPM)), Subpart D (Comparability of Ambient Data to the NAAQS), Subpart F (Air Quality Index (AQI) Reporting), and Subpart G (Federal Monitoring). The network plan also addresses the following regulatory requirements:      40 CFR Part 58 Appendix A - Quality Assurance Requirements for Monitors used in Evaluations of National Ambient Air Quality Standards 40 CFR Part 58 Appendix C - Ambient Air Quality Monitoring Methodology 40 CFR Part 58 Appendix D - Network Design Criteria for Ambient Air Quality Monitoring 40 CFR Part 58 Appendix E - Probe and Monitoring Path Siting Criteria for Ambient Air Quality Monitoring 40 CFR Part 58, Appendix G – Uniform Air Quality Index (AQI) and Daily Reporting The following information is covered in this network plan:     Purpose and type of monitoring conducted at each site; Detailed descriptions and metadata for each site; Metadata for each pollutant monitor; Three years of criteria pollutant data from each monitor; Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 5           Design value metrics that identify the monitoring site with the highest O 3, and PM2.5 concentrations measured over the past 3 years; The minimum quantity of monitors required for each criteria pollutant; Summaries of pollutant data by network and required statistical analyses; The quality and suitability of pollutant data for comparison to the National Ambient Air Quality Standards (NAAQS); The compliance status of monitors, including exceedance days and violations; Proposed changes to the pollutant networks, sites and monitoring methods planned for the current year; Brief information regarding special purpose and/or research-driven air monitors, if operated; The reporting of real-time pollutant and meteorological data to the public via the MCAQD web map and AIRNow; Any requests for waivers from specific air monitoring requirements, if applicable; Public comments received and MCAQD’s responses regarding the final draft of the Annual Monitoring Network Plan. Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 6 Figure 1 2024 Maricopa County Air Monitoring Sites Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 7 Table 3 MCAQD Air Monitoring Instruments by Site Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 8 Clean Air Act and Criteria Pollutants The Clean Air Act (CAA), and its amendments, provide the framework for pertinent State/Local/Tribal agencies to assess and protect air quality through an air monitoring program. Unless generated for research, special studies, or unless otherwise noted, each monitor meets the requirements of 40 CFR Part 58 – Subpart G - Appendices A, B, C, D, and E, where applicable. This means that the data MCAQD produces are of acceptable quality for NAAQS comparisons and compliance determinations, which is the primary purpose for generating the data. Please note that 40 CFR Part 58 Subpart G Appendix B applies to PSD monitoring only, and that no PSD monitoring was conducted within Maricopa County during this time period. MCAQD monitors for five criteria pollutants, which are: 1. Carbon monoxide (CO) 2. Nitrogen oxides (NOx) with nitrogen dioxide (NO2) used as the indicator compound 3. Ozone (O3) 4. Particulate matter ≤10 micrometers (PM10) and ≤2.5 micrometers (PM2.5) 5. Sulfur dioxide (SO2) The National Ambient Air Quality Standards The U.S. EPA regulates criteria pollutants according to the NAAQS, which establish ambient levels for each, using health and welfare-based criteria. There are two sets of NAAQS standards. As per CAA §109(b), the primary NAAQS are designed to provide an adequate margin of safety that is requisite to protecting public health. The secondary NAAQS are designed to protect public welfare from any known or anticipated adverse effects associated with the presence of a pollutant in the ambient air such as damage to properties such as farm crops and buildings, visibility impairment in national parks and wilderness areas, and for the protection of ecosystems. NAAQS are geared toward improving air quality in geographical areas where the current quality is unacceptable as well as preventing air quality deterioration in geographical areas where the air is relatively free of pollution. Since each pollutant has different health effects and environmental damage potential, NAAQS level(s) are different for each pollutant. Some pollutants have standards for both long-term and short-term averaging times. The short-term standards are designed to protect against acute health effects, while the long-term standards are designed to protect against chronic health effects. The NAAQS are not static. The CAA requires that they undergo periodic review using the most recent medical, epidemiological, physiological, and ecosystem research available. Historically, when a NAAQS level changes; the new level(s) is lower. The NAAQS review is a lengthy process that assesses the science upon which each NAAQS is based as well as the standard itself. The Clean Air Scientific Advisory Committee (CASAC) provides independent advice to the U.S. EPA concerning the need to change a standard. In addition, comments are solicited from the public. More information regarding the NAAQS review process is available at EPA’s website. Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 9 U.S. EPA’s Regional Offices oversee the enforcement of the CAA, and MCAQD falls under the jurisdiction of EPA Region 9. U.S. EPA OAQPS oversees the air monitoring program at a national level, leads regulatory and/or policy changes affecting air monitoring operations and quality requirements, and engages in the review of the NAAQS. Table 4 National Ambient Air Quality Standards Pollutant Standard Type Carbon Monoxide (CO) Lead (Pb) primary and secondary Nitrogen Dioxide (NO2) PM10 PM2.5 Ozone (O3) * Particle Matter (PM) primary Sulfur Dioxide (SO2) Averaging Time 8 hours Level Form 9 ppm 1 hour Rolling 3month average 35 ppm Not to be exceeded more than once per year 0.15 μg/m3 Not to be exceeded primary 1 hour 100 ppb 98th percentile of 1-hour daily maximum concentrations, averaged over 3 years primary and secondary 1 year 53 ppb Annual Mean Annual fourth-highest daily maximum 8-hour concentration, averaged over 3 years Annual fourth-highest daily maximum 8-hour concentration, averaged over 3 years Annual mean, averaged over 3 years Annual mean, averaged over 3 years 98th percentile, averaged over 3 years primary and secondary (2015) 8 hours 0.070 ppm primary and secondary (2008) 8 hours 0.075 ppm primary 1 year 9.0 μg/m3 secondary 1 year 15.0 μg/m3 primary and secondary 24 hours 35 μg/m3 24 hours 150 μg/m3 Not to be exceeded more than once per year on average over 3 years 75 ppb 99th percentile of 1-hour daily maximum concentrations, averaged over 3 years primary and secondary primary 1 hour Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 10 Pollutant Standard Type Averaging Time Level Form Not to be exceeded more than once per year * Maricopa County is designated as Moderate for 2008 and Marginal for 2015 O 3 standard. secondary 3 hours 0.5 ppm Source: https://www.epa.gov/criteria-air-pollutants/naaqs-table https://www3.epa.gov/airquality/greenbook/anayo_az.html Forecasting and Reporting Air Quality Conditions This section provides information regarding the use and reporting of continuous, real-time data at the County and national level. It also provides historical information on how the reporting of air quality conditions has improved over the years. Air Quality Forecasting Forecasting air quality depends upon having air quality data available that can be put into a model which generates information needed for meteorologists to make forecasts. Monitoring instrumentation measures and reports hourly data to monitoring organizations (MO) for distribution to AirNow. The readily available data are invaluable to air quality forecasters because they can better predict what the Air Quality Indicators (AQI) will be. The Arizona Department of Environmental Quality (ADEQ) and MCAQD developed a year-round air quality forecasting and “restriction” reporting process for the Phoenix metropolitan area. In Maricopa County, ADEQ is lead for air quality forecasting and issuing a “High Pollution Advisory” (HPA) or a “Health Watch” (HW), while MCAQD designates a “No Burn Day”. MCAQD’s website provides a description of each of these restrictions and provides helpful information on improving air quality. The EPA Air Quality Index and NowCast Since the 1950s, as per 40 CFR Part 58, Appendix G, the Uniform Air Quality Index (AQI) and Daily Reporting, the EPA has required that MOs report air quality conditions to the public regarding criteria pollutant health risks based upon data from their network. To do so, EPA developed the AQI, which is a health risk communication tool that converts pollutant concentrations into six health-impact related color-coded indices based upon the NAAQS. Members of the public use the AQI forecast to reduce their exposure to air pollution and its associated health effects by modifying their daily activities. The AQI graduated color scheme is shown in Figure 2. Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 11 Figure 2 The Air Quality Index Source: 40 CFR Part 58, Appendix G – Uniform Air Quality Index and Daily Reporting (AQI) Basics In the early 2000s, AirNow began using “NowCast” values that tried to reflect current conditions. However, values were based upon each pollutant’s NAAQS averaging time, and it was recognized that these formulas do not respond well to real-time, rapidly changing air quality conditions. For instance, in the desert areas of the Southwest during the monsoon season, dust storms often emerge and dissipate within several hours. These events can drive PM10, and sometimes PM2.5, concentrations into the unhealthy range. Since the NAAQS averaging time for PM10 is 24 hours, a dust storm the evening before can cause air quality conditions to show in the orange range or higher the following day even though the sky is clear and no impact for the prior day’s event is affecting present conditions. Smoke from a brief fire can adversely affect air quality for PM2.5 likewise. The abundance of continuous data in the last decade has furthered our understanding of pollutants, especially PM2.5. This information helped improve the NowCast formulas so values better reflect rapidly changing conditions. To develop the new formulas, EPA analyzed millions of data points gathered from all parts of the U.S. Since PM 10, PM2.5, and O3 make up most air pollution concerns throughout the U.S., the updated NowCast reports on health risks related to these pollutants, only. Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 12 The formulas use a shorter averaging time when a pollutant’s concentration is high and a longer averaging time when a pollutant’s concentration is low, and conditions are stable. To read more about how the most recent NowCast formulas were developed, visit the AirNow FAQ section. Figure 3 AirNow Web Maps The EPA’s AirNow website communicates the status of air quality conditions throughout the country. The MCAQD has participated in the AirNow program since 2001. The MCAQD distributes 1-hour continuous pollutant and select meteorological data to the AirNow website. The AirNow maps cover a geographical area as far east as Queen Creek, as far south as Casa Grande, and as far west as the town of Palo Verde. Air quality data from other Local, Tribal, and National Park Service air monitoring operations within Arizona populate the map as well. The Maricopa County Interactive Air Quality Map The MCAQD provides real-time data on our website using an interactive air quality map with three layers of information. Figure 4 shows the default ‘Current Conditions’ map, which uses the latest NowCast formula to provide a site’s Maximum NowCast value for either PM 10, PM2.5 or O3, as well as the latest formulas for each of the three pollutants’ NowCast values. The Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 13 second tab shows the AQI developed by an unofficial, rolling formula. The map also serves as a way to gather Raw Data from the air quality monitors, which provides hourly CO, NO 2, O3, PM2.5, SO2, and 5-minute concentrations for PM10 and meteorological data from each site. Figure 4 MCAQD Air Quality Status Map Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 14 Air Monitoring Strategies and Surveillance System Design Overview of Air Monitoring Requirements and System Design The MCAQD operated and maintained 23 ambient air monitoring sites throughout Maricopa County in 2024. The sites’ start-up dates range from 1961 for Central Phoenix to 2021 for the Eastwood site. Land use patterns around the sites vary from densely populated urban areas to sparsely populated rural settings. The sites’ elevations range from 845 feet above sea level at Buckeye to 5190 feet above sea level at the top of Humboldt Mountain. MCAQD chose each site and its pollutant monitors based on specific EPA requirements, special requests from EPA, and/or specific needs of the County. Requirements for operating an ambient air monitoring program are found in 40 CFR Parts 50 and 58. The MCAQD holds the Primary Quality Assurance Organization (PQAO) designation for the County’s ambient air monitoring network and is fully responsible for designing and operating the total air monitoring surveillance system and managing the pollutant data generated. MCAQD operates air monitors at EPA-approved State and Local Air Monitoring Stations (SLAMS), which includes near-road monitoring stations. On occasion, special air monitoring initiatives involve temporarily operating monitors designated as Special Purpose Monitors (SPM), as well as special studies. This section details how each Ambient Air Quality network is designed to obtain “representative” data as per 40 CFR Part 58 Appendix D. To determine compliance with the NAAQS, EPA-approved air monitors must be used to collect pollutant data. The EPA classifies approved monitor methods into one of three categories: a federal reference method (FRM), a federal equivalent method (FEM), or an approved regional method (ARM). The MCAQD uses FRM and FEM monitors. This practice ensures high-quality data are used for compliancedriven decisions. However, data from research monitors, e.g., non-compliance-related monitors, can be used to develop state and/or federal attainment and maintenance plans, further evaluate regional air quality models used in developing emissions control strategies, tracking trends in air pollution, and evaluating the impact control measures are having on improving air quality. Any shortterm research data collected by the MCAQD can be made available to decision makers, but the data are not reported to AQS. Within Maricopa County, ADEQ collects compliance data as well as research data at the JLG Supersite via the following EPA monitoring networks: National Core multi-pollutant site (NCore), Photochemical Ambient Monitoring Stations (PAMS), Chemical Speciation Network (CSN), and National Air Toxics Trends Stations (NATTS). ADEQ also collects air toxics Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 15 samples for the Urban Air Toxics Monitoring Program (UATMP) at MCAQD’s South Phoenix site. The data from these networks are reported to EPA and should be available in AQS and/or another EPA database. In addition to producing an annual network plan, the EPA requires a five-year network assessment as per 40 CFR Part 58.10. The 5-year assessment is best served by collaborating with EPA, ADEQ, and other local and/or tribal Monitoring Organizations. MCAQD last completed the assessment in 2020 and will be submitting an updated assessment this year. The assessment process continues to improve, and MCAQD works with other Monitoring Organizations regarding network design issues as needed. Monitoring Organizations within Arizona may provide support to each other by exchanging technical services and/or knowledge when problems arise with instrumentation or when conducting special studies. Basic Air Monitoring Objectives Each ambient air monitor must have a designated basic monitoring objective. The objectives in Table 5 apply to establishing required SLAMS monitoring stations and choosing the general locations for additional monitoring sites. The objectives are not listed based on importance or priority; however, each objective is important and must be considered individually. Table 5 Basic SLAMS Air Monitoring Objectives Objective Description Provide air pollution data to the general public in a timely manner Data can be presented to the public in a number of ways including air quality maps, newspapers, MOs, and EPA websites, and as part of weather forecasts and public advisories. Support compliance Data from EPA-approved monitors for NAAQS pollutants will with ambient air be used for comparing an area’s air pollution levels. quality standards and emissions strategy development Support for air pollution research studies Supplemental data useful with health effect assessments, atmospheric processes, or monitoring methods development work. Source: 40 CFR Part 58 Appendix D, 1.1(a – c) Monitor Types Pollutant monitor types must be designated as shown in Table 6 and are based upon how the data will be used and how long the monitor will remain in operation. The MCAQD’s air Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 16 monitoring network is comprised of SLAMS, which gather data for comparison to the NAAQS. MCAQD has operated SPMs during 2024 to collect additional PM 2.5 data for reassessing the PM2.5 non-attainment area. Table 6 Monitor Types Name Description SLAMS EPA-approved, compliance monitor typically operated on a long-term basis. Measure criteria pollutants for comparison to the NAAQS. (State and Local Air Monitoring Stations) SPM (Special Purpose Monitors) PSD (Prevention of Significant Deterioration) A monitor typically operated on a short-term basis and not necessarily EPA-approved. These monitors are useful for gathering and reporting preliminary information regarding air quality in a local area quickly and over a short-term period, which is less than two years. In the event of a geographical area’s population increasing or data indicating that a SLAMS is more appropriate; an SPM may be reclassified to SLAMS and potentially outfitted with a different method. 40 CFR Part 58.20 Subpart C A monitor typically operated for less than two years prior to a source opening in a protected Class A area and usually required by the permitting authority. PSDs are operated for the purpose of establishing the effect on air quality of the emissions from a proposed source for purposes of preventing significant deterioration to a “protected” area, e.g., a Class 1 area. Class 1 areas include national parks and wilderness areas where a major effort is underway to improve visibility and air quality. Source: 40 CFR Part 58 Site Types To support the three basic monitoring objectives, each site must be identified as one of the six “site types” shown below and may vary within each pollutant’s network. The site type is key to informing air quality professionals and the public about a pollutant’s peak concentration levels. The six general site types as defined in 40 CFR Part 58, Appendix D.1 are:   Sites for determining the highest concentrations expected to occur in the area covered by the network. Sites for measuring typical concentrations in areas of high population density (population exposure). Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 17     Sites for determining the impact of significant sources or source categories on air quality. Sites for determining general background concentration levels. Sites for determining the extent of regional pollutant transport among populated areas and in support of secondary standards. Sites for measuring air pollution impacts to visibility, vegetation damage, or other welfare-based impacts. Monitoring Scales (Spatial Scales of Representativeness) To help link the site type with a monitor’s basic monitoring objective and physical location, EPA uses the spatial scale of representativeness concept as described in 40 CFR Part 58, Appendix D 1.2 (a) and (b). The goal is to correctly match the spatial scale represented by an air sample with the spatial scale most appropriate for the site type, air pollutant to be measured, and the monitoring objective. Table 7 shows the scales of representativeness that are of most interest for the air monitoring site types described above. Table 7 Spatial Scales of Representativeness Name Distance Micro Scale 0 to 100 meters Middle Scale 100 to 500 meters Neighborhood Scale 0.5 to 4 kilometers Urban Scale 4 to 50 kilometers Regional Scale 10s to 100s of kilometers National and Global Scales Characterize the nation and the globe as a whole Source: 40 CFR Part 58, Appendix D 1.2 Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 18 Overview of the Air Monitoring Sites According to the U.S. Census Bureau, Maricopa County’s most recent population estimate is 4,551,524 people (U.S. Census Bureau: Quick Facts Population Estimate for Maricopa County). As per 40 CFR Part 58, the EPA mandates the minimum quantity of monitors required by a pollutant’s network to properly represent the County’s population. The MCAQD pollutant networks are designed using the concept of spatial scale representativeness and monitoring objectives. This results in Ambient Air Monitoring networks that meet, and in most cases exceed, the minimum quantity of monitors required by EPA. Additional information on the siting of air monitors can be found in Appendix I of this network plan. Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 19 SUMMARY OF NETWORK RESULTS AND REQUIRED INFORMATION Determining Data Quality and Acceptability This section details the results obtained from the 2024 monitoring year. The EPA has established data quality and measurement quality objectives for pollutant data. In addition to 40 CFR Part 58, the EPA QA Handbook for Air Pollution Measurement Systems: “Volume II: Ambient Air Quality Monitoring Program provides extensive information regarding the quality system and its components. There are seven data quality indicators (DQI) established by the EPA to determine the quality of ambient air data. Data must meet each indicator’s requirement to be certified and acceptable for use by decision makers for NAAQS compliance determinations, researchers, and the public. These indicators are precision, bias, completeness, comparability, detectability, representativeness, and sensitivity. “Timeliness” of data collection, validation, and upload to AQS is important as well. “Accuracy” is now defined as a measure of the overall agreement of a measurement to a known value and includes a combination of random error (precision) and systematic error (bias) components of both sampling and analytical operations. The MCAQD’s personnel evaluate data using these indicators, with precision, bias, and completeness being the most crucial to evaluate on an ongoing basis. Data Completeness Before considering any data set valid, it must first pass a data recovery, or completeness, test. The test requirements begin with checking completeness at hourly and 24-hour concentration values, or ‘samples. The pollutant data measurements from continuous analyzers are based on a valid hour, while filter samples from manual samplers are based on a 24-hour sampling period from midnight-to-midnight. Equation 1 shows the calculation for the data completeness percentage, which is the quantity of valid measurements divided by the quantity of scheduled measurements, multiplied by one hundred. For data, completeness must be greater than 75% for a data set to pass the first validity test. Furthermore, data completeness requirements may vary and use multiple levels of data aggregation, e.g., 1-hour, 3-hour, 8-hour, 24-hour, quarterly, annual, and multiple years. Equation 1 𝐷𝑎𝑡𝑎 𝐶𝑜𝑚𝑝𝑙𝑒𝑡𝑒𝑛𝑒𝑠𝑠 (%) = 𝑄𝑢𝑎𝑛𝑡𝑖𝑡𝑦 𝑜𝑓 𝑉𝑎𝑙𝑖𝑑 𝑀𝑒𝑎𝑠𝑢𝑟𝑒𝑚𝑒𝑛𝑡𝑠 × 100% 𝑄𝑢𝑎𝑛𝑡𝑖𝑡𝑦 𝑜𝑓 𝑆𝑐ℎ𝑒𝑑𝑢𝑙𝑒𝑑 𝑀𝑒𝑎𝑠𝑢𝑟𝑒𝑚𝑒𝑛𝑡𝑠 Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 20 Table 8 2024 Criteria Pollutant Data Completeness for SLAMS Pollutant CO O3 Percent Complete 89.4 98.1 NO2 SO2 PM2.5 PM10 Total 95.2 99.0 98.0 96.9 96.4 Source: EPA AQS 2024 Data Completeness Report (AMP430) Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 21 Summary of 2024 Criteria Pollutant Data This section covers the 2024 data generated by each network. Carbon Monoxide (CO) Figure 5 shows the CO monitoring sites operating in 2024. A CO monitor is required at one MCAQD near-road site. The CO data were reported to AQS, and the data are suitable for comparison to the NAAQS. Figure 5 2024 CO Monitoring Sites In 2024, no exceedances or violations of the 1-hour or 8-hour CO NAAQS occurred at any MCAQD sites, and concentrations remained well below NAAQS levels. Table 9 shows the maximum and second maximum 1-hour and 8-hour CO averages measured. Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 22 Table 9 2024 CO Average Data Summary CO 1-hour Average Maximum CO 1-hour Average 2nd Maximum CO 8-hour Average Maximum CO 8-hour Average 2nd Maximum (ppm) (ppm) (ppm) (ppm) Buckeye 0.9 0.8 0.7 0.7 Central Phoenix 3.6 3.1 2.6 2.3 Eastwood 1.5 1.4 1.1 1.1 Mesa 1.9 1.8 1.5 1.4 South Phoenix 3.7 3.2 2.6 2.0 West Chandler 1.7 1.6 1.2 1.1 West Phoenix 4.0 3.4 2.8 2.7 Required Active Additional Near-Road Monitors Near-Road Monitors Near-Road Monitors Needed 1 1 0 Site Source: EPA AQS 2024 Quicklook Criteria Report (AMP450) Table 10 2024 CO Monitor Requirements CBSA Population Estimate (2024) 38060 4,673,096 Source: U.S. Census Bureau: Quick Facts Population Estimate for Maricopa County Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 23 Nitrogen Dioxide (NO2) Figure 6 shows the five NO2 monitoring sites which operated in 2024. The NO 2 monitors at the Buckeye, Central Phoenix, and West Phoenix sites are designated as SLAMS, which represent the NO2 concentrations within Maricopa County. The near-road network requires two NO 2 monitors in the metropolitan area. The Thirty-Third and Eastwood site monitors are the designated near-road monitors representing the microscale by collecting source-oriented emissions from vehicular traffic on heavily travelled highways within Maricopa County. Figure 6 2024 NO2 Monitoring Sites Data from both the area-wide and near-road monitors were reported to AQS, and the data are suitable for comparison to the NAAQS. Table 11 shows that no exceedances or violations of the NO2 annual or 1-hour NAAQS were recorded at Maricopa County monitoring sites in 2024. Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 24 Table 11 2024 NO2 1-hour Data Summary NO2 3-Year 98th Percentiles Average NO2 Maximum NO2 Annual Average NO2 98th Percentile (ppb) (ppb) (ppb) Buckeye 38.0 7.99 32.0 32.6 Central Phoenix 62.0 14.98 58.0 54.6 Eastwood 57.0 14.25 51.0 48.3 Thirty-Third 66.0 25.35 60.0 59.6 West Phoenix 55.0 15.24 52 50.3 Site Name (ppb) Source: EPA AQS database 2022 – 2024 Quicklook Criteria Report (AMP450) Additional information required by EPA for the near-road NO 2 monitors is shown in Table 12. Table 12 2024 NO2 Monitor Requirements CBSA Population Estimate (2024) 38060 4,673,096 Max AADT Count (2021) 295,833 Required NearRoad Monitors Active NearRoad Monito rs Needed NearRoad Monitor s Required AreaWide Monitors Active AreaWide Monitors Needed AreaWide Monitors 2 2 0 1 3 0 Sources: U.S. Census Bureau: Quick Facts Population Estimate for Maricopa County; Traffic Monitoring – ADOT Annual Average Daily Traffic Count Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 25 Ozone (O3) Figure 7 shows the seventeen SLAMS O 3 monitors which operated in 2024. The data were reported to AQS, and data are suitable for comparison to the NAAQS. In 2024, there were fifty-six days when at least one O 3 monitor exceeded the 2015 8-hour NAAQS of 70 ppb. When the 2008 8-hour O 3 NAAQS of 75 ppb is applied to the 2024 data, twenty-five days were observed where at least one O3 monitor exceeded the standard. An O3 site is determined to have exceeded a NAAQS when the annual 4 th highest daily maximum 8-hour concentration, averaged over the previous 3 years is greater than the daily 8hour average NAAQS. Sixteen O3 sites exceeded the 2015 NAAQS of 70 ppb and nine of those O3 sites exceeded the 2008 NAAQS of 75 ppb. As a result of documented wildfires in 2024, MCAQD is submitting Exceptional Event (EE) packages for 46 of the 56 exceedance days noted. Per the EPA’s Exceptional Event Rule, an EE is an uncontrollable event that was caused by natural sources of pollution or an event that is not expected to recur at a given location. If EPA Region 9 concurs, the O 3 concentrations measured during the EE are not used to determine compliance with the NAAQS. If these and previous year’s EEs are accepted by the EPA, nine O 3 sites will have exceeded the 2015 NAAQS of 70 ppb and zero sites will have exceeded the 2008 NAAQS of 75 ppb. The EE counts shown below on Table 13. Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 26 Figure 7 2024 O3 Monitoring Sites Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 27 Table 13 2024 O3 Eight-hour Average Summary Site 1st 8-hr Maximum (ppm) 2nd 8-hr Maximum (ppm) 3rd 8-hr Maximum (ppm) 4th 8-hr Maximum (ppm) Qty. of Days Quantity of > 0.070 ppm EEs Blue Point 0.089† 0.088† 0.082† 0.080† 25 23 Buckeye 0.076† 0.075† 0.071† 0.070 3 3 Cave Creek 0.086† 0.080† 0.075† 0.074† 8 8 Central Phoenix 0.084† 0.083† 0.083† 0.076† 13 12 Dysart 0.092† 0.083† 0.083† 0.082† 10 10 Falcon Field 0.087† 0.085† 0.084† 0.079† 36 28 Fountain Hills 0.089† 0.088† 0.082† 0.080† 26 20 Glendale 0.089† 0.083† 0.082† 0.081† 18 18 Humboldt Mt. 0.084† 0.083† 0.075† 0.074† 8 8 Mesa 0.089† 0.088† 0.081† 0.081† 26 19 North Phoenix 0.086† 0.083† 0.078† 0.077† 23 20 Pinnacle Peak 0.086† 0.086† 0.079† 0.078† 24 19 South Phoenix 0.077† 0.074† 0.070 0.070 2 2 South Scottsdale 0.089† 0.085† 0.084† 0.082† 30 22 Tempe 0.083† 0.081† 0.077† 0.075† 15 12 West Chandler 0.083† 0.079† 0.075† 0.073† 5 4 West Phoenix 0.090† 0.086† 0.082† 0.082† 20 18 † - Indicates an exceedance of the 2015 8-hr NAAQS Source: EPA AQS 2024 Quicklook Criteria Report (AMP450); MCAQD 2024 O3 Exceedance Day Report Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 28 Table 14 2024 O3 Monitor Requirements CBSA 38060 County Maricopa Population Estimate (2024) 4,673,096 3-Year Design Value 80 ppb 3-Year Design Value Site AQS ID 04-013-2001 Site Name Glendale Monitoring Organization MCAQD MCAQD 8-Hour Maximum Concentration MCAQD 8-Hour Maximum Concentration Site(s) AQS ID 04-013-4010 Site Name Dysart MSA Maximum 8-Hour Concentration MSA Maximum Concentration Site(s) 92 ppb 92 ppb AQS ID 04-013-4010 Site Name Dysart Monitoring Organization MCAQD Required Monitors 3 Active Monitors 17 Additional Monitors Needed 0 Source: EPA AQS 2024 Preliminary Design Value Report (AMP480); EPA AQS 2024 Quicklook Criteria Report (AMP450); U.S. Census Bureau: Quick Facts Population Estimate for Maricopa County Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 29 Particulate Matter ≤10 Micrometers (PM10) Figure 8 shows the fifteen PM10 SLAMS monitors, which operated in 2024. All PM 10 monitoring stations operate continuous PM10 analyzers that collect 5-minute and hourly averaged data. All data were submitted to AQS and are suitable for comparison to the NAAQS. The EPA does not require PM10 analyzers to be collocated at the PQAO level or the national level. Figure 8 2024 PM10 Monitoring Sites Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 30 A PM10 exceedance day is defined to be a day in which the 24-hour PM10 average is in excess of 155 µg/m3. The PM10 NAAQS are violated when the expected number of exceedances at a monitor is more than one per year on average over the previous three years. The expected number of exceedances for a site is estimated using a formula provided in 40 CFR Part 50 Appendix K. The formula uses the number of days sampling occurs and the number of valid samples that can be collected. A 3-year average of these estimated days is then used to determine compliance. The annual weighted average for each PM 10 monitoring site is displayed on Table 14 for informational purposes. In recent years, some PM10 exceedances occurring in the Maricopa County CBSA have been successfully attributed to an Exceptional Event (EE). Per the EPA’s Exceptional Event Rule, an EE is an uncontrollable event that was caused by natural sources of pollution or an event that is not expected to recur at a given location. ADEQ makes the determination of which events to classify as exceptional, then they submit documentation to EPA supporting the contention that the exceedance(s) was due to an EE. If EPA Region 9 concurs, the PM 10 concentrations measured during the EE are not used to determine compliance with the NAAQS. The EE counts shown below on Table 14 are current as of this review’s publishing. In 2024, there were eight days that exceeded the 24-hour PM10 NAAQS at at least one of MCAQD’s sites, and two sites, South Phoenix and West 43rd , violated the NAAQS. Table 15 shows the PM10 24-hour NAAQS status and data summary, including EE data values. Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 31 Table 15 2024 PM10 24-Hour Average Summary Site Name Maximum 24-Hour Average (µg/m3) Three-year 2nd Number of Average Maximum2424-hour Annual Hour NAAQS Expected Average Exceedances Exceedance (µg/m3) Rate 121 0 0.3 Buckeye 151 Central 228†‡ 151 1 Phoenix Durango 152 146 0 Complex Dysart 106 103 0 Glendale 110 72 0 Higley 141 110 0 Mesa 153 67 0 North 112 103 0 Phoenix South 181 177 4 Phoenix South 160† 120 1 Scottsdale Tempe 119 96 0 West 191† 113 1 Chandler West 43rd 200†‡ 165†‡ 4 Avenue West 205†‡ 153 1 Phoenix Zuni Hills 83 79 0 † - Indicates an exceedance of the standard ‡ - Data are associated with exceptional event flag Annual Weighted Average (µg/m3) Quantity of EEs 46.3 0 0.7 36.0 1 0.3 30.3 0 1 0 0.7 0 32.6 21.4 35.3 21.1 0 0 0 0 0 20.5 0 1.4† 35.5 2 0.4 29.6 1 0 22.2 0 1 32.9 1 4.1† 59.2 0 0.7 31.7 0 0.3 28.7 0 Source: EPA AQS 2024 Preliminary Design Value Report (AMP480); EPA AQS 2024 Quicklook Criteria Report (AMP450) Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 32 Table 16 2024 PM10 Monitor Requirements CBSA 38060 County Maricopa Population Estimate (2024) 4,673,096 MCAQD Maximum 24-Hour Concentration 228 µg/m 3 MCAQD Maximum Concentration for Site AQS ID 04-013-3002 Site Name Central Phoenix 228 µg/m 3 MSA Maximum 24-Hour Concentration MSA Maximum Concentration Site AQS ID 04-013-3002 Site Name Central Phoenix Monitoring Organization MCAQD Required Monitors 6-10 Active Monitors 15 Additional Monitors Needed 0 Source: EPA AQS 2024 Quicklook Criteria Report (AMP450); U.S. Census Bureau: Quick Facts Population Estimate for Maricopa County Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 33 Particulate Matter ≤2.5 Micrometers (PM2.5) Figure 9 shows the eight PM2.5 sites which operated in 2024. All PM2.5 monitors are designated as SLAMS. Data were reported to AQS, and data are suitable for comparison to the NAAQS. Figure 9 2024 PM2.5 Monitoring Sites Each PM2.5 site operates a continuous FEM monitor that provides hourly concentration data used for NAAQS comparison. To meet the EPA’s QA collocation requirements for the PM 2.5 network, a secondary monitor is operated at the West Phoenix site. This site operates one FEM continuous analyzer designated as the primary monitor and one FRM filter-based PM 2.5 sampler designated as the secondary monitor. The FRM filter-based secondary sampler collects a 24-hour sample for QA purposes every 12 days. The U.S. EPA OAQPS produces the annual sampling calendar each year and posts it on the AMTIC website; this calendar is used for determining the days on which samples are collected from the site. Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 34 Maricopa County has been designated as non-attainment based on the 2024 Revised Annual PM NAAQS. Final EPA designation is expected to be made on February 7, 2026. MCAQD continually assesses the existing PM2.5 network to ensure it adequately represents air quality in Maricopa County. In the event that MCAQD needed to move or change a violating PM 2.5 monitor, the following procedure would be followed. MCAQD would hold a public hearing regarding the requested change. Details and documentation of the requested change, as well as all public comments, would then be forwarded to the EPA Region 9 for approval. Any action on MCAQD’s part will be dependent on EPA Region 9 approval. Please note that this statement is general in nature and required in this AMNP by 40 CFR Part 58. MCAQD does not currently have any violating PM2.5 monitors, nor does it have any proposals to move any PM2.5 monitors. In 2024, there were eight days that exceeded the 24-hour PM 2.5 NAAQS of 35 µg/m3 at one or more MCAQD sites. Table 17 summarizes the 24-hour and annual data from the primary monitors only, including EE data values. Table 17 2024 PM2.5 24-Hour and Annual Averages Maximum 24Hour Average Site Name Concentration 2nd Maximum 24- 98th Percentile 24Hour Average Hour Average Concentration Concentration Annual Average Concentration (µg/m3) (µg/m3) (µg/m3) (µg/m3) 102.8† 42.3† 32.9 10.46 Eastwood 44.8† 24.3 18.9 7.03 Glendale 46.6† 42.5† 19.0 7.45 Mesa 32.1 27.6 18.8 7.03 North Phoenix 47.5† 34.5 20.0 7.25 South Phoenix 160.9† 70.6† 29.5 11.61 Tempe 29.9 27.3 17.7 6.93 West Phoenix 186.3† 60.0† 32.2 10.13 Durango Complex † - Indicates an exceedance of the standard. ‡ - Data are associated with exceptional event flag Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 35 Source: EPA AQS 2024 Quicklook Criteria Report (AMP450) Compliance with the primary and secondary annual NAAQS is determined by averaging three consecutive years of a site’s annual mean value using the 24-hour, or daily, concentrations. The annual PM2.5 NAAQS is met when the 3-year annual average concentration is less than or equal to 9.0 µg/m3 at a monitoring site. The 3-year averages at three monitoring sites, Durango Complex, South Phoenix, and West Phoenix are in exceedance of the PM 2.5 annual NAAQS of 9.0 µg/m3. Table 18 summarizes the 3-year annual average data. Table 18 PM2.5 3-Year Annual Averages 2022 Annual Average Concentration 2023 Annual Average Concentration 2024 Annual Average Concentration 3-Year Annual Average Concentration (µg/m3) (µg/m3) (µg/m3) (µg/m3) Durango Complex 9.75 9.75 10.46 9.99† Eastwood 7.88 7.56 7.03 7.49 Glendale 6.17 6.99 7.45 6.87 Mesa 6.30 6.54 7.03 6.62 North Phoenix 6.95 6.97 7.25 7.06 South Phoenix 11.09 9.29 11.61 10.66† Tempe 7.81 7.20 6.93 7.31 West Phoenix 10.20 9.5 10.13 9.94† Site Name † - Indicates an exceedance of the standard. Source: EPA AQS 2024 Quicklook Criteria Report (AMP450) Compliance with the primary and secondary 24-hour PM 2.5 NAAQS is determined by averaging 3 consecutive years of the 24-hour 98th percentile concentration values from all eligible sites. The 24-hour NAAQS is met when the 3-year average concentration value is less than or equal to 35 µg/m3. In 2024, there were eight exceedance days, three monitors that exceeded the primary 24-hour PM2.5 NAAQS and no monitors exceeded the secondary 24-hour PM 2.5 NAAQS. Table 19 summarizes the 3-year 24-hour 98th percentile data from the FEM analyzers. Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 36 Table 19 PM2.5 3-Year 24-Hour Averages of the 98th Percentile 2022 98th Percentile 24-Hour Average Concentration 2023 98th Percentile 24-Hour Average Concentration 2024 98th Percentile 24-Hour Average Concentration (µg/m3) (µg/m3) (µg/m3) Durango Complex 28.0 31.7 32.9 30.9 Eastwood 17.7 16.1 18.9 17.6 Glendale 19.1 22.9 19.0 20.3 Mesa 16.7 14.8 18.8 16.8 North Phoenix 21.5 17.6 20.0 19.7 South Phoenix 29.5 26.0 29.5 28.3 Tempe 17.1 16.1 17.7 17.0 West Phoenix 33.0 31.7 32.2 32.3 Site Name 3-Year 98th Percentile 24Hour Average Concentration (µg/m3) * - Indicates that the mean does not satisfy summary criteria, e.g., data completeness Source: EPA AQS 2024 Quicklook Criteria Report (AMP450) Table 20 shows additional information required by EPA. The PM 2.5 annual and daily design values include any measurements submitted as an EE for EPA’s concurrence. In 2024 two exceptional events were submitted. Maricopa County exceeds the minimum requirement for PM2.5 monitors for the CBSA. Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 37 Table 20 2024 PM2.5 Data Required by EPA CBSA 38060 County Maricopa Population Estimate (2022) 4,673,096 MCAQD Annual Design Value 10.7 µg/m3 MCAQD Annual Design Value Site AQS ID 04-013-4003 Site Name South Phoenix 32 µg/m3 MCAQD 24-Hour Design Value MCAQD 24-Hour Design Value Sites AQS ID 04-013-0019 Site Name West Phoenix 186.3 µg/m3 MCAQD Max 24-Hour Concentration MCAQD Max 24-Hour Concentration Site AQS ID 04-013-0019 Site Name West Phoenix 186.3 µg/m3 MSA Max 24-Hour Concentration MSA Max 24-Hour Concentration Site AQS ID 04-013-0019 Site Name West Phoenix Monitoring Organization MCAQD Required Monitors 3 Active Monitors 8 Additional Monitors Needed 0 Source: EPA AQS 2024 Preliminary Design Value Report (AMP480); EPA AQS 2024 Quicklook Criteria Report (AMP450); U.S. Census Bureau: Quick Facts Population Estimate for Maricopa County Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 38 Sulfur Dioxide (SO2) Figure 10 shows the two SO2 SLAMS monitors which operated in 2024. The data were reported to AQS, and the data are suitable for NAAQS comparison. Figure 10 2024 SO2 Monitoring Sites Sulfur dioxide has a 1-hour primary standard and a 3-hour secondary standard. In 2024, no exceedances of the SO2 primary 1-hour or secondary 3-hour standard were recorded at Maricopa County monitoring sites; and no site violated the SO 2 NAAQS. The EPA requires that the highest 5-minute average per hour per day be reported to AQS; however, there is no 5minute SO2 NAAQS standard. Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 39 Table 21 2024 SO2 Data Summary 1-hour Maximum Concentration 1-hour 2nd Maximum Concentration (ppb) (ppb) Central Phoenix 6.0 4.0 3.0 Durango Complex 8.0 7.0 6.0 Site 1-hour 99th Percentile (ppb) Source: EPA AQS 2024 Quicklook Criteria Report (AMP450) The minimum required quantity of SO2 monitors operating within the MCAQD’s network is based on either the Population Weighted Emissions Index (PWEI) and/or the EPA R9 Administrator’s input (see 40 CFR Part 58 - Appendix D 4.4.3). Table 22 2024 SO2 Monitor Requirements CBSA County Total SO2 Population Emitted Estimate (2020) (2024) 38060 Maricopa 4,673,096 (tpy) 1167 Population Weighted Emission Index (million personstons/yr) 5454 Additional Required Active Monitors Monitors Monitors Needed 1 2 0 Source: The EPA’s National Emissions Inventories (NEI) database – 2022 NEI Data U.S. Census Bureau: Quick Facts Population Estimate for Maricopa County Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 40 Summary of 2024 Criteria Pollutant NAAQS Status This section summarizes information regarding the status of each pollutant relative to its NAAQS level. It also provides detailed information regarding pollutants that are in NAAQS violation. Table 23 summarizes the 2024 NAAQS exceedances and violations by pollutant. Table 23 2024 NAAQS Exceedances and Violation Summary Pollutant NAAQS Status  O3    PM10   PM2.5 SO2 NO2 CO  On fifty-six (56) unique days, at least one monitor exceeded the 2015 8hour primary/secondary NAAQS unless EPA Region 9 concurs with the EE demonstration submittals. On twenty-five (25) days, at least one monitor exceeded the 2008 8-hour primary/secondary NAAQS. Sixteen (16) sites will violate the 2015 8-hour primary/secondary NAAQS unless EPA Region 9 concurs with the EE demonstration submittals. On eight (8) unique days, at least one monitor exceeded the 24-hour primary/secondary 1987 NAAQS. Two (2) sites will violate the primary/secondary 1987 NAAQS unless EPA Region 9 concurs with the EE demonstration submittals. If submittals are approved, then no site will violate the NAAQS. On eight (8) unique days, at least one monitor exceeded the 2012 24-hour primary/secondary NAAQS. Three (3) sites violated the 24-hour or annual primary/secondary 2012 NAAQS.  No exceedances or violations of the primary annual or 1-hour 2010 NAAQS or the annual secondary 2010 NAAQS occurred.  No exceedances or violations of the 1-hour or annual primary 2010 NAAQS or annual secondary 2012 NAAQS occurred.  No exceedances or violations of the 1-hour or 8-hour primary 2011 NAAQS occurred. Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 41 2024 O3 Exceedance, Violation, and Exceptional Event Information This section discusses the monitoring results of the O 3 network, and the 2015 NAAQS violation status based upon years 2022 through 2024. O3 NAAQS Exceedances The 2015 O3 NAAQS level of 0.070 ppm is exceeded when a rolling 8-hour average is 0.071 ppm or higher. Fifty-six exceedance days occurred in 2024. Figure 11 shows the 2024 O 3 exceedance dates and concentrations by site. Exceedance day values associated with an EE are shown in red. The 2008 O3 NAAQS level of 0.075 ppm is exceeded when a rolling 8-hour average is 0.076 ppm or higher. Twenty-five exceedances of the 2008 standard occurred in 2024. O3 Exceptional Events and Status of EPA Concurrence Fourty-six (46) exceedance days appear to be influenced by smoke from wildfires for which EE packages are being developed for submittal to EPA. The EPA must concur with the EE demonstration package before O3 data can be omitted from NAAQS comparisons. O3 NAAQS Violation Status - Including Exceptional Event Data A site violates the 2015 O3 NAAQS when the 3-year average of the 4th highest rolling 8-hour average concentration measured each year exceeds 0.070 ppm. Figure 12 shows the sites that violated the 2015 O3 NAAQS and includes 2022 through 2024 average data associated with EE submittals. O3 NAAQS Violation Status - Excluding Exceptional Event Data Figure 13 shows the sites that would violate the 2015 O 3 NAAQS in 2024, if the EPA concurs with the EE demonstration packages submitted for 2022 through 2024. The graph also shows that no sites would violate the 2008 O 3 NAAQS if exceptional events are approved. Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 42 Figure 11 Ozone Exceedance Days Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 43 Figure 12 2024 O3 NAAQS Violations by Site Including Exceptional Events Source: EPA AQS 2024 O3 8-Hour Maximum Values Report (AMP440) Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 44 Figure 13 2024 O3 NAAQS Violations by Site Excluding Exceptional Events Source: EPA AQS 2023 O3 8-Hour Maximum Values Report (AMP440) Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 45 2024 PM10 Exceedance, Violation, and Exceptional Event Information This section discusses the monitoring results of the PM10 network and NAAQS violation status based upon years 2022 - 2024. PM10 NAAQS Exceedances A PM10 exceedance occurs when a monitor’s 24-hour average concentration from midnight-to-midnight is 155.5 µg/m3 or higher. Figure 14 shows the site and date of PM10 exceedances that occurred in 2024. All 2024 exceedances of the PM10 NAAQS qualify for Exceptional Events consideration and demonstration packages have been developed for EPA’s review. The 24-hour concentrations shown below include hourly PM10 data flagged as an Exceptional Event in red. Figure 14 2024 PM10 Exceedance Days PM10 24-Hour NAAQS Violation Status - Including Exceptional Event Data As per 40 CFR Part 50.6 (a), a site violates the primary and/or secondary 24-hour PM10 NAAQS when the calculated “rate of expected exceedances” is greater than one (> 1) when averaged over three consecutive years. Table 24 includes EE data and shows the maximum three-year 24-hour PM10 averages, the calculation of expected exceedances for each year, and the calculation of three-year average for the rate of expected exceedances. If the EPA does not concur with the EE demonstration packages submitted for years 2022 through 2024; then, two sites, South Phoenix and West 43rd will violate the PM10 NAAQS as shown in the 3-Year Average Rate of Expected Exceedances column. Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 46 Table 24 2024 Violations of the PM10 24-Hour NAAQS Including EE Data Site 2022 24-Hour Maximum (µg/m3) 153 101 2023 24-Hour Expected Maximum Exceedances (µg/m3) 0 181‡ 0 207‡ Buckeye Central Phoenix Durango 98 0 319‡ Complex Dysart 206‡ 2 194‡ Glendale 89 0 119 Higley 160‡ 1 165‡ Mesa 74 0 112 North Phoenix 68 0 110 South Phoenix 97 0 107 South Scottsdale 100 0 148 Tempe 73 0 97 West Chandler 191‡ 2.1 152 West 43rd 316‡ 5.2 216‡ West Phoenix 127 0 182‡ Zuni Hills 167‡ 1 146 ‡ - MCAQD flagged this exceedance as an EE in AQS †- indicates a violation of the NAAQS 1 0 2024 24-Hour Maximum (µg/m3) 151 228†‡ 1 152 0 0.3 1 0 1.2 0 0 0 0 0 0 3 1 0 106 110 141 153 112 181 160† 119 191† 200†‡ 205†‡ 83 0 0 0 0 0 4 1 0 1 4 1 0 1 0 0.7 0 0 1.4† 0.4 0 1 4.1† 0.7 0.3 Expected Exceedances Expected Exceedances 3-Year Average Rate of Expected Exceedances 0 1 0.3 0.7 Source: EPA AQS database 2022 - 2024 Quicklook Criteria Parameters Report (AMP450) PM10 24-Hour NAAQS Violation Status - Excluding Exceptional Event Data The ADEQ submits EE packages to EPA Region 9 for the 2024 PM10 exceedance days. If EPA concurs with the EE demonstration packages submitted for 2022 through 2024, then only W. 43rd will violate the PM10 NAAQS in 2024. Table 25 excludes PM10 data considered the result of an EE, regardless of the EPA’s concurrence status. The NAAQS violation status is shown in the 3-Year Average Rate of Expected Exceedances column. Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 47 Table 25 2024 Violations of the PM10 NAAQS Excluding Data Flagged as an EE 2022 2023 24-hour 24-hour Maximum Expected Maximum 3 Site (µg/m ) Exceedances (µg/m3) Buckeye 153 0 146 Central Phoenix 101 0 151 Durango Complex 98 0 112 Dysart 136 0 140 Glendale 89 0 119 Higley 99 0 143 Mesa 74 0 112 North Phoenix 68 0 110 South Phoenix 97 0 107 South Scottsdale 100 0 148 Tempe 73 0 97 West Chandler 115 0 152 West 43rd Avenue 148 0 146 West Phoenix 127 0 109 Zuni Hills 126 0 146 †- indicates a violation of the NAAQS 2024 Expected Exceedances 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 24-hour Maximum (µg/m3) 151 151 152 106 110 141 153 112 168† 120 119 113 200† 205† 83 Source: EPA AQS database 2022 - 2024 Quicklook Criteria Parameters Report (AMP450) Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 48 Expected Exceedances 0 0 0 0 0 0 0 0 1 0 0 0 4 1 0 3-Year Average Rate of Expected Exceedances 0 0 0 0 0 0 0 0 0.3 0 0 0 1.3† 0.3 0 2024 PM2.5 Exceedance, Violation, and Exceptional Event Information This section discusses the monitoring results of the PM 2.5 network in 2024. It includes NAAQS exceedance information and violation status for 2024. PM2.5 Annual NAAQS Exceedance and Violation Status The annual primary NAAQS for PM2.5 was lessened from 12.0 µg/m3 to a more stringent standard of 9.0 µg/m3 during 2024. The secondary annual NAAQS for PM2.5 is 15.0 µg/m3. In 2024, there were three monitors, Durango Complex, South Phoenix, and West Phoenix that exceeded the primary annual NAAQS of 9.0. No monitors exceeded the secondary NAAQS. Each site’s annual PM2.5 average was shown previously on Table 18. PM2.5 24-Hour NAAQS Exceedance and Violation Status The 24-hour primary and secondary NAAQS levels for PM 2.5 are 35 µg/m3. If the 24-hour blockaverage concentration from midnight-to-midnight at a site is 35.5 µg/m 3 or higher, then it is counted as an exceedance. A summary of the 24-hour average data can be found in Table 17 and Figure 15 below. If the 24-hour 3-year average of the 98 th percentile exceeds 35 µg/m3, then the 24-hour NAAQS is violated. The data presented in Table 19 shows no exceedances or violations of the 98th percentile average data. Figure 15 2024 PM2.5 Exceedance Days Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 49 PM2.5 Exceptional Events and Status of EPA Concurrence Two PM2.5 exceptional events will be submitted by MCAQD for fireworks usage on 1/1/2024 and 12/31/2024. Concurrence was reached on all PM2.5 AQS submitted data during the data certification process. Shared Air Monitoring Responsibilities For the MCAQD monitoring network, EPA requested that MCAQD work with the other State/Local/Tribal MOs within the MSA/CBSA to develop a shared monitoring agreement as specified by EPA Region 9. This is to ensure that each pollutant’s network is adequately represented throughout Maricopa and Pinal Counties, which is the MSA/CBSA geographical area. ADEQ has been designated to develop the agreements with counties that operate stations within the MSA/CBSA. As of May 2025, no agreement has been developed. Information Regarding Additional Air Monitoring within Maricopa County ADEQ operates its own air monitoring surveillance system within the State of Arizona, which includes the JLG Supersite in central Phoenix. JLG Supersite is part of the national air monitoring surveillance system and numerous SLAMS monitors operate there. In addition, ADEQ collects research data for other air monitoring programs at both the JLG Supersite and MCAQD’s South Phoenix site. The research data support EPA’s air monitoring programs that include, but are not limited to, identifying airborne air toxics and ozone precursors, identifying the chemical composition of PM2.5, and measuring visual haze. Specifically, ADEQ performs air monitoring in Maricopa County for the Chemical Speciation Network (CSN), the Interagency Monitoring of Protected Visual Environments (IMPROVE), the National Air Toxics Trends Stations (NATTS), the National Core multi-pollutant monitoring stations (NCore), the Photochemical Assessment Monitoring Stations (PAMS), and the Urban Air Toxics Monitoring Program (UATMP). They also operate visibility cameras and meteorological monitors within the County. Occasionally, ADEQ may temporarily use other sites for special projects. For more information about ADEQ’s network, consult the ADEQ Air Quality Division’s website. Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 50 REFERENCES                      The eCFR Title 40, Parts 50, 53, and 58 U.S. EPA Office of Air and Radiation: https://www.epa.gov/aboutepa/about-office-airand-radiation-oar U.S. EPA Criteria Pollutant Information: https://www.epa.gov/criteria-air-pollutants U.S. EPA NAAQS Information: https://www.epa.gov/criteria-air-pollutants/naaqs-table U.S. EPA Network Assessments/Plans webpage: https://www.epa.gov/amtic/statemonitoring-agency-annual-air-monitoring-plans-and-network-assessments U.S. EPA NowCast Presentation: https://www3.epa.gov/airnow/ani/pm25_aqi_reporting_nowcast_overview.pdf U.S. EPA AIRNow webpage: https://gispub.epa.gov/airnow/ U.S. EPA AQS AirData website: https://www.epa.gov/outdoor-air-quality-data U.S. EPA NowCast Calculator webpage: https://www3.epa.gov/airnow/aqicalctest/nowcast.htm U.S. EPA OAQPS QA Webpage: Ambient Air Monitoring Quality Assurance | US EPA U.S. EPA Exceptional Events webpage: https://www.epa.gov/air-qualityanalysis/treatment-data-influenced-exceptional-events U.S. EPA List of Areas Protected by the Regional Haze Program: https://www.epa.gov/visibility/list-areas-protected-regional-haze-program U.S. EPA National Emissions Inventory database: https://www.epa.gov/air-emissionsinventories/2014-national-emissions-inventory-nei-data EPA Metadata Specifications: https://www.epa.gov/geospatial/epa-metadatatechnical-specification EPA Region 9 Air Program Information: http://www.epa.gov/region9/air/index.html Arizona SIP Information: https://azdeq.gov/SIP ADEQ Natural and Exceptional Events Information: https://azdeq.gov/naturalandexceptional_events MCAQD Online Interactive Air Quality Map: http://alert.fcd.maricopa.gov/alert/Google/v3/airnow.html MCAQD Annual Monitoring Plans and Network Assessments: http://www.maricopa.gov/1669/Air-Monitoring-Network-Plans-Assessments MCAQD Restrictions Web page: https://www.maricopa.gov/5914/Outreach MCAQD Dusts Sources, Control and Training: https://www.maricopa.gov/1913/DustSources-Control-and-Training Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 51 APPENDIX I - Air Monitoring Data by Site Site information includes site location, spatial scale, site type, and site description. Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 52 Blue Point (BP) (04-013-9702) Site Location Bush Hwy. & Usery Pass Rd., Maricopa County Spatial Scale Urban Site Type Maximum O3 Concentration Site Description: This site began operating in July 1995. This SLAMS location monitors for O3. Meteorological monitoring includes ambient temperature and wind speed/direction. This site is located approximately 40 miles east of the Phoenix metropolitan area and represents maximum O3 concentrations downwind from an urban area. Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 53 BLUE POINT County Abbreviation: BP AQS ID: 04-013-9702 Address: Bush Hwy. & Usery Pass Rd., Maricopa County Lat/Long Coordinates: 33.54558 N, -111.60972 W Metropolitan Statistical Area (MSA): 6200 Phoenix-Mesa General Information Pollutant O3 Parameter Code 44201 Parameter Occurrence Code 1 Collection Frequency Continuous Analysis Method (filter samples only) Not Applicable Any Proposal to Remove or Move Monitor? No Does monitor operation meet 40 CFR Part 58, Subpart G – Yes Appendices A, C, D, and E? Is site suitable for comparison to the annual PM2.5 NAAQS as per Not Applicable §58.30? Are Data Comparable to Respective NAAQS? Yes Appendix A Requirements - Quality Assurance Requirements for SLAMS and SPMs Number of 1-Point QC (Precision) Checks Performed (Gases) 30 Frequency of 1-Point QC (Precision) Checks Bi-Weekly Number of Flow Rate Verifications Performed (PM) Not Applicable Frequency of Flow Rate Verifications Number of PE Audits Performed 2 05/06/2024 Dates of PE Audits 11/14/2024 Annual Precision & PE Audit Reports Submitted to AQS? Yes Date of Annual Data Certification Submission 04/30/25 Appendix B Requirements - PSD Monitoring - Not Applicable Appendix C Requirements - Monitoring Methodology Date Sampling Started 01/01/1993 Monitor Type SLAMS Monitor Make - Model Teledyne API – Model 400T Method Code 087 Method Type (FRM, FEM, ARM) FEM Appendix D Requirements - Network Design Criteria Site Type Max Ozone Concentration Basic Monitoring Objective NAAQS Comparison Monitoring Scale (Spatial Scale Represented) Urban Monitoring Season Jan-Dec Network Meets Minimum Number of Monitors Required? Yes Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 54 BLUE POINT Appendix E Requirements - Probe and Monitoring Path Siting Criteria Distance between collocated samplers Not Applicable Probe Height (distance above ground level to inlet) 2.9 meters Airflow Arc 360º Probe Sample Line Material FEP Pollutant Sample Residence Time (seconds) 8.51 Horizontal 1.9 meters Distance from Supporting Structure/Roof (horizontal distance and vertical distance to probe/inlet) Vertical 0 meters no Horizontal obstruction Distance from Obstructions on Roof (horizontal distance to obstruction and vertical height of obstruction above probe/inlet) no Vertical obstruction Horizontal 15.8 meters Distance from Obstructions Not on Roof (horizontal distance to the obstruction and vertical height of obstruction above probe/inlet) Vertical 0 meters Distance from Dripline of Closest Tree(s) 8.8 meters* Distance to Furnace or Flue No Furnace or Flue Nearest Major Roadway Bush Hwy. Distance and Direction to Road 160 meters, S Average Daily Traffic Count 6,110 Groundcover Pavement Source: EPA AQS 2024 DQI Report (AMP256); EPA AQS 2024 QA Raw Assessment Report (AMP 251 ) * MCAQD is aware that these measurements do not meet siting requirements. The trees closest to the monitor inlets are not on MCAQD property. MCAQD is working with property owners to change the situation to make adjustments to achieve compliance. Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 55 Buckeye (BE) (04-013-4011) Site Location AZ Hwy. 85 & MC Hwy. 85, Buckeye Spatial Scale Neighborhood for CO, and PM10 Urban for NO2 and O3 Site Type Population Exposure and Upwind Background for O3 Site Description: The Buckeye site began operating in August 2004. This SLAMS location monitors for CO, NO2, O3, and PM10. Meteorological monitoring includes ambient temperature, barometric pressure, relative humidity, and wind speed/direction. The site is located at the Maricopa County Department of Transportation - Southwest Facility. The immediate area is agriculture and encroaching residential development. Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 56 BUCKEYE County ID: BE AQS ID: 04-013-4011 Address 26453 W MC85 Coordinates: 33.36985 N, -112.62068 W Metropolitan Statistical Area (MSA): 6200 Phoenix-Mesa General Information Pollutant CO NO2 O3 PM10 Parameter Code 42101 42602 44201 81102 Parameter Occurrence Code 1 1 1 1 Collection Frequency Continuous Continuous Continuous Continuous Not Not Analysis Method (filter samples only) Not Applicable Not Applicable Applicable Applicable Any Proposal to Remove or Move No No No No Monitor? Does monitor operation meet 40 CFR Part 58, Subpart G – Appendices A, C, Yes Yes Yes Yes D, and E? Is site suitable for comparison to the Not Not Not Applicable Not Applicable annual PM2.5 NAAQS as per §58.30? Applicable Applicable Are Data Comparable to Respective Yes Yes Yes Yes NAAQS? Appendix A Requirements - Quality Assurance Requirements for SLAMS and SPMs Number of 1-Point QC (Precision) 31 34 34 Checks Performed (Gases) Not Applicable Frequency of 1-Point QC (Precision) Bi-Weekly Bi-Weekly Bi-Weekly Checks Number of Flow Rate Verifications 25 Not Performed (PM) Not Applicable Not Applicable Applicable Frequency of Flow Rate Verifications Bi-Weekly Number of PE Audits Performed 2 2 2 4 01/08/24 01/09/24 01/22/24 06/11/24 04/02/24 Dates of PE Audits 07/08/24 07/08/24 12/11/24 07/08/24 10/31/24 Annual Precision & PE Audit Reports Yes Yes Yes Yes Submitted to AQS? Date of Annual Data Certification 4/30/25 Submission Appendix B Requirements - PSD Monitoring - Not Applicable Appendix C Requirements - Monitoring Methodology Date Sampling Started 08/01/2004 08/01/2004 08/01/2004 Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 08/01/2004 57 Monitor Type BUCKEYE SLAMS SLAMS SLAMS SLAMS Teledyne Teledyne API – Teledyne API – Thermo – Monitor Make - Model API – Model Model 300T Model 400T TEOM 1405-S 200T Method Code 093 099 087 079 Not PM Monitor Flow Type Not Applicable Not Applicable Low Volume Applicable Not PM Monitor Collection Type Not Applicable Not Applicable Size Specific Applicable Method Type (FRM, FEM, ARM) FRM FRM FEM FEM Appendix D Requirements - Network Design Criteria Population Population Upwind Population Site Type Exposure Exposure Background Exposure NAAQS NAAQS NAAQS NAAQS Basic Monitoring Objective Comparison Comparison Comparison Comparison Monitoring Scale Neighborhood Urban Urban Neighborhood (Spatial Scale Represented) Monitoring Season Sep-Mar Jan-Dec Jan-Dec Jan-Dec Network Meets Minimum Number of Yes Yes Yes Yes Monitors Required? Appendix E Requirements - Probe and Monitoring Path Siting Criteria Distance between collocated Not Not Not Applicable Not Applicable samplers Applicable Applicable Probe Height (distance above ground 4.1 meters 4.1 meters 4.1 meters 4.3 meters level to inlet) Airflow Arc 360º 360º 360º 360º Not Probe Sample Line Material FEP FEP FEP Applicable Pollutant Sample Residence Time Not 6.18 7.75 9.87 (seconds) Applicable Distance from Supporting Horizontal 0 meters 0 meters 0 meters 0 meters Structure/Roof (horizontal distance and vertical Vertical 1.5 meters 1.5 meters 1.5 meters 1.6 meters distance to probe/inlet) Distance from no no Horizontal no obstruction no obstruction Obstructions on Roof obstruction obstruction (horizontal distance to obstruction and vertical no no Vertical no obstruction no obstruction height of obstruction obstruction obstruction above probe/inlet) Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 58 BUCKEYE Distance from Horizontal Obstructions Not on Roof (horizontal distance to the obstruction and vertical Vertical height of obstruction above probe/inlet) Distance from Dripline of Closest Tree(s) no obstruction no no obstruction obstruction no obstruction no obstruction no no obstruction obstruction no obstruction 12.8 meters 12.8 meters 12.8 meters 12.8 meters No Furnace No Furnace or No Furnace or or Flue Flue Flue Nearest Major Roadway U.S. Hwy 85 U.S. Hwy 85 U.S. Hwy 85 31 meters, Distance and Direction to Road 31 meters, N 31 meters, N 31 meters, N N Average Daily Traffic Count 2,895 2,895 2,895 2,895 Groundcover Pavement Pavement Pavement Pavement Source: EPA AQS 2024 DQI Report (AMP256); EPA AQS 2024 QA Raw Assessment Report (AMP 251 ) Distance to Furnace or Flue No Furnace or Flue U.S. Hwy 85 Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 59 Cave Creek (CC) (04-013-4008) Site Location 32nd St. & Carefree Hwy., Cave Creek Spatial Scale Urban Site Type Maximum O3 Concentration Site Description: The Cave Creek site began operating in July 2001. This SLAMS location monitors for O3. The monitoring equipment was moved into a new shelter at the Cave Creek monitoring site during the year of 2024, approximately 70 feet to the south of the previous shelter. The measurements included in the following table are for this new shelter. Meteorological monitoring includes ambient temperature, barometric pressure, rain, relative humidity, and wind speed/direction. The site is located at the Maricopa County Cave Creek Recreation Area. Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 60 CAVE CREEK County ID: CC AQS ID: 04-013-4008 Address: 37019 N Lava Ln., Phoenix Coordinates: 33.82169 N, -112.01726 W Metropolitan Statistical Area (MSA): 6200 Phoenix-Mesa General Information Pollutant O3 Parameter Code 44201 Parameter Occurrence Code 1 Collection Frequency Continuous Analysis Method (filter samples only) Not Applicable Any Proposal to Remove or Move Monitor? Yes Does monitor operation meet 40 CFR Part 58, Subpart G – Yes Appendices A, C, D, and E? Is site suitable for comparison to the annual PM2.5 NAAQS as per Not Applicable §58.30? Are Data Comparable to Respective NAAQS? Yes Appendix A Requirements - Quality Assurance Requirements for SLAMS and SPMs Number of 1-Point QC (Precision) Checks Performed (Gases) 30 Frequency of 1-Point QC (Precision) Checks Bi-weekly 2Number of Flow Rate Verifications Performed (PM) Not Applicable Frequency of Flow Rate Verifications Number of PE Audits Performed 2 04/01/24 Dates of PE Audits 10/15/24 Annual Precision & PE Audit Reports Submitted to AQS? Yes Date of Annual Data Certification Submission 4/30/25 Appendix B Requirements - PSD Monitoring - Not Applicable Appendix C Requirements - Monitoring Methodology Date Sampling Started 07/20/2001 Monitor Type SLAMS Monitor Make - Model Teledyne - API Model 400T Method Code 087 Method Type (FRM, FEM, ARM) FEM Appendix D Requirements - Network Design Criteria Site Type Max Ozone Concentration Basic Monitoring Objective NAAQS Comparison Monitoring Scale (Spatial Scale Represented) Urban Monitoring Season Jan-Dec Network Meets Minimum Number of Monitors Required? Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan Yes 61 CAVE CREEK Appendix E Requirements - Probe and Monitoring Path Siting Criteria Distance between collocated samplers Not Applicable Probe Height (distance above ground level to inlet) 2.82 meters Airflow Arc 360º Probe Sample Line Material FEP Pollutant Sample Residence Time (seconds) 9.95 Distance from Supporting Structure/Roof Horizontal 0.2 meters (horizontal distance and vertical distance to Vertical 1.68 meters probe/inlet) Distance from Obstructions on Roof (horizontal Horizontal None distance to obstruction and vertical height of Vertical None obstruction above probe/inlet) Distance from Obstructions Not on Roof Horizontal 11.28 meters (horizontal distance to the obstruction and vertical Vertical 0 meters height of obstruction above probe/inlet) Distance from Dripline of Closest Tree(s) 25.30 meters Distance to Furnace or Flue No Furnace or Flue Nearest Major Roadway 32nd St. Distance and Direction to Road 240 meters, NE Average Daily Traffic Count 2,333 Groundcover Pavement Source: EPA AQS 2024 DQI Report (AMP256); EPA AQS 2024 QA Raw Assessment Report (AMP 251 ) Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 62 Central Phoenix (CP) (04-013-3002) Site Location 19th St. & Roosevelt St., Phoenix Spatial Scale Neighborhood Site Type Population Exposure for CO, O3, and PM10 Highest Concentration for NO2 and SO2 Site Description: The Central Phoenix site began operating in June 1962. This SLAMS location monitors for CO, PM10, NO2, O3, and SO2. Meteorological monitoring includes ambient temperature, barometric pressure, and wind speed/direction. This site is located within the Maricopa County Public Health building. Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 63 Pollutant Parameter Code CENTRAL PHOENIX County ID: CP AQS ID: 04-013-3002 Address: 1645 E Roosevelt St., Phoenix Coordinates: 33.45797 N, -112.04659 W Metropolitan Statistical Area (MSA): 6200 Phoenix-Mesa General Information CO NO2 O3 42101 42602 44201 SO2 42401 Parameter Occurrence Code 1 6 1 4 Collection Frequency Continuous Continuous Continuous Continuous Analysis Method Not Not Not Not (filter samples only) Applicable Applicable Applicable Applicable Any Proposal to Remove or Move No No No No Monitor? Does monitor operation meet 40 CFR Part 58, Subpart G – Yes Yes Yes Yes Appendices A, C, D, and E? Is site suitable for comparison to Not Not Not Not the annual PM2.5 NAAQS as per Applicable Applicable Applicable Applicable §58.30? Are Data Comparable to Respective Yes Yes Yes Yes NAAQS? Appendix A Requirements - Quality Assurance Requirements for SLAMS and SPMs Number of 1-Point QC (Precision) Checks Performed (Gases) Frequency of 1-Point QC (Precision) Checks Number of Flow Rate Verifications Performed (PM) Frequency of Flow Rate Verifications Number of PE Audits Performed Dates of PE Audits 31 28 31 30 Bi-weekly Bi-weekly Bi-weekly Bi-weekly Not Applicable Not Applicable Not Applicable Not Applicable 2 1 2 1 05/06/24 10/18/24 04/10/24 06/03/24 12/03/24 02/23/24 Annual Precision & PE Audit Yes Yes Yes Yes Reports Submitted to AQS? Date of Annual Data Certification 4/30/25 Submission Appendix B Requirements - PSD Monitoring - Not Applicable Appendix C Requirements - Monitoring Methodology Date Sampling Started 10/01/1966 01/01/1967 06/01/1967 01/01/1965 Monitor Type SLAMS SLAMS SLAMS SLAMS Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan PM10 81102 4 Continuous Not Applicable No Yes Not Applicable Yes Not Applicable 24 Bi-weekly 4 01/30/24 04/10/24 07/09/24 10/22/24 Yes 04/01/1985 SLAMS 64 CENTRAL PHOENIX Teledyne API Teledyne API - Teledyne API Monitor Make - Model - Model 300T Model 200T Model 400T Method Code 093 099 087 Not Not Not PM Monitor Flow Type Applicable Applicable Applicable Not Not Not PM Monitor Collection Type Applicable Applicable Applicable Method Type (FRM, FEM, ARM) FRM FRM FEM Appendix D Requirements - Network Design Criteria Population Highest Population Site Type Exposure Concentration Exposure NAAQS NAAQS NAAQS Basic Monitoring Objective Comparison Comparison Comparison Monitoring Scale (Spatial Scale Neighborhood Neighborhood Neighborhood Represented) Monitoring Season Jan-Dec Jan-Dec Jan-Dec Teledyne API Model 100T 100 Not Applicable Not Applicable FEM Thermo TEOM 1405-S 079 Highest Concentration NAAQS Comparison Population Exposure NAAQS Comparison Neighborhood Neighborhood Jan-Dec Jan-Dec Network Meets Minimum Number Yes Yes Yes Yes of Monitors Required? Appendix E Requirements - Probe and Monitoring Path Siting Criteria Distance between collocated Not Not Not Not samplers Applicable Applicable Applicable Applicable Probe Height (distance above ground level to 11.8 meters 11.8 meters 11.8 meters 11.8 meters inlet) Airflow Arc 360º 360º 360º 360º Probe Sample Line Material Pollutant Sample Residence Time (seconds) Distance from Horizontal Supporting Structure/Roof (horizontal distance and Vertical vertical distance to probe/inlet) Distance from Horizontal Obstructions on Roof (horizontal distance to Vertical obstruction and vertical Low Volume Size Specific FEM Yes Not Applicable 12.8 meters 360º Not Applicable Not Applicable FEP FEP FEP FEP 9.16 14.5 9.69 9.93 0 meters 0 meters 0 meters 0 meters 0 meters 1.9 meters 1.9 meters 1.9 meters 1.9 meters 2.4 meters 1.6 meters 1.6 meters 1.6 meters 1.6 meters no obstruction 0.9 meters 0.9 meters 0.9 meters 0.9 meters no obstruction Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 65 CENTRAL PHOENIX height of obstruction above probe/inlet) Distance from Horizontal Obstructions Not on Roof (horizontal distance to the obstruction and vertical Vertical height of obstruction above probe/inlet) Distance from Dripline of Closest Tree(s) no obstruction no obstruction no obstruction no obstruction no obstruction no obstruction no obstruction no obstruction no obstruction no obstruction 23.7 meters 23.7 meters 23.7 meters 23.7 meters 26.5 meters Nearest Major Roadway A Distance and Direction to Road Average Daily Traffic Count No Furnace or Flue 16th St. 88 meters, W 31,475 No Furnace or Flue 16th St. 88 meters, W 31,475 No Furnace or Flue 16th St. 88 meters, W 31,475 No Furnace or Flue 16th St. 88 meters, W 31,475 No Furnace or Flue 16th St. 91 meters, W 31,475 Nearest Major Roadway B Roosevelt St. Roosevelt St. Roosevelt St. Roosevelt St. Roosevelt St. Distance and Direction to Road 75 meters, N 75 meters, N 75 meters, N 75 meters, N 75 meters, N Average Daily Traffic Count Groundcover 21,637 Pavement 21,637 Pavement 21,637 Pavement 21,637 Pavement 21,637 Pavement Distance to Furnace or Flue Source: EPA AQS 2024 DQI Report (AMP256); EPA AQS 2024 QA Raw Assessment Report (AMP 251 ) Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 66 Durango Complex (DC) (04-013-9812) Site Location 27th Ave & Durango St., Phoenix Spatial Scale Neighborhood Site Type Highest Concentration Site Description: This site began operating in January 1999. This SLAMS location monitors for PM10, PM2.5, and SO2. Meteorological monitoring includes ambient temperature, barometric pressure, relative humidity, and wind speed/direction. The site is located inside the Maricopa County Department of Transportation storage yard. Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 67 DURANGO COMPLEX County ID: DC AQS ID: 04-013-9812 Address: 2702 RC Esterbrooks Blvd., Phoenix Coordinates: 33.42650 N, -112.11812 W Metropolitan Statistical Area (MSA): 6200 Phoenix-Mesa General Information Pollutant PM10 PM2.5 Parameter Code 81102 88101 Parameter Occurrence Code 1 3 Collection Frequency Continuous Continuous Analysis Method (filter samples only) Not Applicable Not Applicable Any Proposal to Remove or Move Monitor? No No Does monitor operation meet 40 CFR Part 58, Yes Yes Subpart G – Appendices A, C, D, and E? Is site suitable for comparison to the annual Not Applicable Yes PM2.5 NAAQS as per §58.30? Are Data Comparable to Respective NAAQS? Yes Yes SO2 42401 1 Continuous Not Applicable No Yes Not Applicable Yes Appendix A Requirements - Quality Assurance Requirements for SLAMS and SPMs Number of 1-Point QC (Precision) Checks Performed (Gases) Frequency of 1-Point QC (Precision) Checks Number of Flow Rate Checks Performed (PM) Frequency of Flow Rate Verifications Number of PE Audits Performed Dates of PE Audits Not Applicable Not Applicable 30 Bi-Weekly 4 01/08/24 04/02/24 07/09/24 11/06/24 30 Bi-Weekly 4 01/08/24 04/02/24 07/09/24 11/06/24 30 Bi-Weekly Annual Precision & PE Audit Reports Yes Yes Submitted to AQS? Date of Annual Data Certification Submission 4/30/25 Appendix B Requirements - PSD Monitoring - Not Applicable Appendix C Requirements - Monitoring Methodology Date Sampling Started 07/01/1999 07/01/2005 Monitor Type SLAMS SLAMS Thermo Thermo - TEOM Monitor Make - Model TEOM 1405-DF 1405-DF Method Code 208 182 PM Monitor Flow Type Low Volume Low Volume PM Monitor Collection Type Dichotomous Dichotomous Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan Not Applicable 2 05/16/24 11/06/24 Yes 01/01/2011 SLAMS Teledyne API – 100T 100 Not Applicable Not Applicable 68 DURANGO COMPLEX Method Type (FRM, FEM, ARM) FEM FEM Appendix D Requirements - Network Design Criteria Population Highest Site Type Exposure Concentration NAAQS NAAQS Basic Monitoring Objective Comparison Comparison Monitoring Scale (Spatial Scale Represented) Neighborhood Neighborhood Monitoring Season Jan-Dec Jan-Dec Network Meets Minimum Number of Monitors Yes Yes Required? Appendix E Requirements - Probe and Monitoring Path Siting Criteria Distance between collocated samplers Not Applicable Not Applicable Probe Height (distance above ground level to 4.4 meters 4.4 meters inlet) Airflow Arc 360º 360º Probe Sample Line Material Not Applicable Not Applicable Pollutant Sample Residence Time (seconds) Not Applicable Not Applicable Distance from Supporting Horizontal 0 meters 0 meters Structure/Roof (horizontal distance and vertical distance to Vertical 1.7 meters 1.7 meters probe/inlet) Distance from Obstructions on no Horizontal no obstructions Roof (horizontal distance to obstructions obstruction and vertical height no of obstruction above Vertical no obstructions obstructions probe/inlet) Distance from Obstructions Not Horizontal 53.9 meters 53.9 meters on Roof (horizontal distance to the obstruction and vertical Vertical 0 meters 0 meters height of obstruction above probe/inlet) Distance from Dripline of Closest Tree(s) 15.5 meters 15.5 meters No Furnace or No Furnace or Distance to Furnace or Flue Flue Flue th Nearest Major Roadway 27 Ave 27th Ave Distance and Direction to Road 78 meters, E 76 meters, E Average Daily Traffic Count 19,349 19,349 Groundcover Pavement Pavement FEM Highest Concentration NAAQS Comparison Middle Jan-Dec Yes Not Applicable 4.4 meters 360º FEP 6.51 0.13 meters 1.8 meters no obstructions no obstructions 53.9 meters 0 meters 20.1 meters No Furnace or Flue 27th Ave 76 meters, E 19,349 Pavement Source: EPA AQS 2024 DQI Report (AMP256); EPA AQS 2024 QA Raw Assessment Report (AMP 251 ) Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 69 Dysart (DY) (04-013-4010) Site Location Bell Rd. & Dysart Rd., Surprise Spatial Scale Neighborhood Site Type Population Exposure Site Description: The Dysart site began operating in July 2003. This SLAMS location monitors for O3 and PM10. Meteorological monitoring includes ambient temperature, barometric pressure, relative humidity, and wind speed/direction. The site is located at the Maricopa County Facility Maintenance Yard on the corner of Bell Rd. and Dysart Rd. The site is in a growing population area in the northwest valley and is surrounded by a variety of land use. Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 70 DYSART County ID: DY AQS ID: 04-013-4010 Address: 16825 N Dysart Rd., Surprise Coordinates: 33.63718 N, -112.34185 W Metropolitan Statistical Area (MSA): 6200 Phoenix-Mesa General Information Pollutant O3 PM10 Parameter Code 44201 81102 Parameter Occurrence Code 1 1 Collection Frequency Continuous Continuous Not Not Analysis Method (filter samples only) Applicable Applicable Any Proposal to Remove or Move Monitor? No No Does monitor operation meet 40 CFR Part 58, Subpart G – Yes Yes Appendices A, C, D, and E? Is site suitable for comparison to the annual PM2.5 NAAQS as per Not Not §58.30? Applicable Applicable Are Data Comparable to Respective NAAQS? Yes Yes Appendix A Requirements - Quality Assurance Requirements for SLAMS and SPMs Number of 1-Point QC (Precision) Checks Performed (Gases) 27 Not Applicable Frequency of 1-Point QC (Precision) Checks Bi-Weekly Number of Flow Rate Verifications Performed (PM) 24 Not Applicable Frequency of Flow Rate Verifications Bi-Weekly Number of PE Audits Performed 2 4 01/03/24 04/09/24 04/09/24 Dates of PE Audits 10/17/24 07/10/24 10/17/24 Annual Precision & PE Audit Reports Submitted to AQS? Yes Yes Date of Annual Data Certification Submission 4/30/25 Appendix B Requirements - PSD Monitoring - Not Applicable Appendix C Requirements - Monitoring Methodology Date Sampling Started 7/21/2003 Monitor Type SLAMS Teledyne API Monitor Make - Model – 400T Method Code 087 Not PM Monitor Flow Type Applicable Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 07/14/2003 SLAMS Thermo TEOM 1405-S 079 Low Volume 71 DYSART Not Size Specific Applicable Method Type (FRM, FEM, ARM) FEM FEM Appendix D Requirements - Network Design Criteria Population Population Site Type Exposure Exposure NAAQS NAAQS Basic Monitoring Objective Comparison Comparison Monitoring Scale (Spatial Scale Represented) Neighborhood Neighborhood Monitoring Season Jan-Dec Jan-Dec Network Meets Minimum Number of Monitors Required? Yes Yes Appendix E Requirements - Probe and Monitoring Path Siting Criteria Not Not Distance between collocated samplers Applicable Applicable Probe Height (distance above ground level to inlet) 4.2 meters 4.4 meters Airflow Arc 360º 360º Not Probe Sample Line Material FEP Applicable Not Pollutant Sample Residence Time (seconds) 4.79 Applicable Distance from Supporting Structure/Roof Horizontal 0 meters 0 meters (horizontal distance and vertical distance to Vertical 1.7 meters 1.5 meters probe/inlet) no no Horizontal Distance from Obstructions on Roof (horizontal obstructions obstructions distance to obstruction and vertical height of no no obstruction above probe/inlet) Vertical obstructions obstructions Distance from Obstructions Not on Roof (horizontal Horizontal 36.5 meters 36.5 meters distance to the obstruction and vertical height of Vertical 0 meters 0 meters obstruction above probe/inlet) Distance from Dripline of Closest Tree(s) 49.3 meters 51.2 meters No Furnace or No Furnace or Distance to Furnace or Flue Flue Flue Nearest Major Roadway A Dysart Dysart Distance and Direction to Road 17 meters, W 12 meters, W Average Daily Traffic Count 12,000 12,000 Nearest Major Roadway B Bell Rd Bell Rd Distance and Direction to Road 495 meters, N 460 meters, N Average Daily Traffic Count 35,957 35,957 Source: EPA AQS 2024 DQI Report (AMP256); EPA AQS 2024 QA Raw Assessment Report (AMP 251 ) PM Monitor Collection Type Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 72 Eastwood (EA) (04-013-4021) Site Location 36th St. & Interstate 10 Spatial Scale Micro Site Type SourceOriented Site Description: The Eastwood site began operating in March 2021. This SLAMS location monitors for CO, NO2, and PM2.5. Meteorological monitoring includes ambient temperature, relative humidity, and wind speed/direction. The site is one of two near-road air monitoring sites and is located on the south side of the I10 East. Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 73 EASTWOOD County ID: EA AQS ID: 04-013-4021 Address: 4135 S. 36th St., Phoenix Coordinates: 33.41046 N, -112.00264 W Metropolitan Statistical Area (MSA): 6200 Phoenix-Mesa General Information Pollutant CO NO2 PM2.5 Parameter Code 42101 42602 88101 Parameter Occurrence Code 1 1 3 Collection Frequency Analysis Method (Filter samples only Analytical Laboratory (filter samples only) Any Proposal to Remove or Move Monitor? Does monitor operation meet 40 CFR Part 58, Subpart G – Appendices A, C, D, and E? Is site suitable for comparison to the annual PM2.5 NAAQS as per §58.30? Are Data Comparable to Respective NAAQS? Continuous Continuous Continuous Not Applicable Not Applicable Not Applicable Not Applicable Not Applicable Not Applicable No No No Yes Yes Yes Not Applicable Not Applicable Yes Yes Yes Yes Appendix A Requirements - Quality Assurance Requirements for SLAMS and SPMs Number of 1-Point QC (Precision) Checks Performed (Gases) Frequency of 1-Point QC (Precision) Checks Number of Flow Rate Verifications Performed (PM) Frequency of Flow Rate Verifications Number of PE Audits Performed Dates of PE Audits Annual Precision & PE Audit Reports Submitted to AQS? Date of Annual Data Certification Submission 30 31 Bi-Weekly Bi-Weekly Not Applicable Not Applicable Not Applicable 27 Bi-Weekly 2 2 03/04/24 08/05/24 02/01/24 08/14/24 Yes Yes 3 03/04/24 06/10/24 08/14/24 Yes 4/30/25 Appendix B Requirements - PSD Monitoring - Not Applicable Appendix C Requirements - Monitoring Methodology Date Sampling Started 03/05/2021 03/05/2021 03/05/2021 Monitor Type SLAMS SLAMS SLAMS Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 74 Monitor Make - Model Teledyne - API 300T Teledyne - API 200T Method Code 93 99 Thermo TEOM 1405DF 182 PM Monitor Flow Type Not Applicable Not Applicable Low Volume PM Monitor Collection Type Not Applicable Not Applicable Dichotomous Method Type (FRM, FEM, ARM) FRM FRM FEM Appendix D Requirements - Network Design Criteria Site Type Source-Oriented Source-Oriented Basic Monitoring Objective NAAQS Comparison NAAQS Comparison SourceOriented NAAQS Comparison Micro Micro Micro Jan-Dec Jan-Dec Jan-Dec Yes Yes Yes Monitoring Scale (Spatial Scale Represented) Monitoring Season Network Meets Minimum Number of Monitors Required? Appendix E Requirements - Probe and Monitoring Path Siting Criteria Distance between collocated samplers Probe Height (distance above ground level to inlet) Airflow Arc Probe Sample Line Material Pollutant Sample Residence Time (seconds) Filter Sample Material Distance from Supporting Structure/Roof (horizontal distance and vertical distance to probe/inlet) Not Applicable Not Applicable Not Applicable 4.3 meters 4.3 meters 4.4 meters 360º 360º 360º FEP FEP Not Applicable 5.29 7.33 Not Applicable Not Applicable Not Applicable Not Applicable Horizontal 0.3 meters 0.3 meters 0 meters Vertical 1.6 meters 1.6 meters 1.7 meters no obstruction no obstruction no obstruction no obstruction 44.8 meters 44.8 meters 0 meters 0 meters 25.6 meters 25.6 meters 28.3 meters Distance to Furnace or Flue No Furnace or Flue No Furnace or Flue No Furnace or Flue Nearest Major Roadway I-10 I-10 I-10 Distance and Direction to Road 24 meters, N 24 meters, N 24 meters, N Average Daily Traffic Count 121,222 121,222 121,222 Groundcover Gravel Gravel Gravel Distance from Obstructions on Roof (horizontal distance to obstruction and vertical height of obstruction above probe/inlet) Distance from Obstructions Not on Roof (horizontal distance to the obstruction and vertical height of obstruction above probe/inlet) Distance from Dripline of Closest Tree(s) Horizontal no obstruction no obstruction 44.8 meters Vertical 0 meters Horizontal Vertical Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 75 Source: EPA AQS 2024 DQI Report (AMP256); EPA AQS 2024 QA Raw Assessment Report (AMP 251 ) Falcon Field (FF) (04-013-1010) Site Location Greenfield Rd. & McKellips Rd., Mesa Spatial Scale Neighborhood Site Type Population Exposure Site Description: This site began operating in June 1989. This SLAMS location monitors for O3. Meteorological monitoring includes ambient temperature and relative humidity. The site is located at a fire station near an airfield within a growing residential area. In 2020, wind speed and wind direction monitoring ceased at this location due to no longer being able to secure a wind tower to the roof of the fire station. The search for a new location in the same general area where an air monitoring shelter can be installed is underway. Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 76 FALCON FIELD County ID: FF AQS ID: 04-013-1010 Address: 4530 E McKellips Rd, Mesa Coordinates: 33.45244 N, -111.73327 W Metropolitan Statistical Area (MSA): 6200 Phoenix-Mesa General Information Pollutant O3 Parameter Code 44201 Parameter Occurrence Code 1 Collection Frequency Continuous Analysis Method (filter samples only) Not Applicable Any Proposal to Remove or Move Monitor? Yes Does monitor operation meet 40 CFR Part 58, Subpart G – Appendices A, C, D, Yes and E? Is site suitable for comparison to the annual PM2.5 NAAQS as per §58.30? Not Applicable Are Data Comparable to Respective NAAQS? Yes Appendix A Requirements - Quality Assurance Requirements for SLAMS and SPMs Number of 1-Point QC (Precision) Checks Performed (Gases) 38 Frequency of 1-Point QC (Precision) Checks Bi-Weekly Number of Flow Rate Verifications Performed (PM) Not Applicable Frequency of Flow Rate Verifications Number of PE Audits Performed 2 01/04/24 Dates of PE Audits 07/11/24 Annual Precision & PE Audit Reports Submitted to AQS? Yes Date of Annual Data Certification Submission 4/30/25 Appendix B Requirements - PSD Monitoring - Not Applicable Appendix C Requirements - Monitoring Methodology Date Sampling Started 06/01/1989 Monitor Type SLAMS Teledyne API – Monitor Make - Model 400T Method Code 087 Method Type (FRM, FEM, ARM) FEM Appendix D Requirements - Network Design Criteria Population Site Type Exposure Basic Monitoring Objective NAAQS Comparison Monitoring Scale (Spatial Scale Represented) Neighborhood Monitoring Season Jan-Dec Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 77 FALCON FIELD Network Meets Minimum Number of Monitors Required? Yes Appendix E Requirements - Probe and Monitoring Path Siting Criteria Distance between collocated samplers Not Applicable Probe Height (distance above ground level to inlet) 8.9 meters Airflow Arc 360º Probe Sample Line Material FEP Pollutant Sample Residence Time (seconds) Distance from Supporting Structure/Roof (horizontal distance and vertical distance to probe/inlet) Distance from Obstructions on Roof (horizontal distance to obstruction and vertical height of obstruction above probe/inlet) Distance from Obstructions Not on Roof (horizontal distance to the obstruction and vertical height of obstruction above probe/inlet) Distance from Dripline of Closest Tree(s) Distance to Furnace or Flue Nearest Major Roadway Distance and Direction to Road Average Daily Traffic Count Groundcover 19.11 Horizontal Vertical 0 meters 3.3 meters Horizontal 5.7 meters Vertical 0 meters Horizontal 41.1 meters Vertical 0 meters 22.9 meters No Furnace or Flue McKellips 58 meters, S 18,337 Pavement Source: EPA AQS 2024 DQI Report (AMP256); EPA AQS 2024 QA Raw Assessment Report (AMP 251 ) Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 78 Fountain Hills (FH) (04-013-9704) Site Location Fountain Hills Blvd. & Palisades Blvd., Fountain Hills Spatial Scale Site Type Neighborhood Maximum O3 Concentration Site Description: The site began operating in April 1996 at a Fountain Hills fire station. This SLAMS location monitors for O3 only. Meteorological monitoring includes ambient temperature, barometric pressure, relative humidity, and wind speed/direction. The site is located approximately 15 miles northeast of the Phoenix metropolitan area and represents maximum O3 concentrations downwind from an urban area. Furthermore, the site sits on the fringes of the central basin district along the predominant summer/fall daytime wind direction. Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 79 FOUNTAIN HILLS County ID: FH AQS ID: 04-013-9704 Address: 16426 E. Palisades Blvd., Fountain Hills Coordinates: 33.61092 N, -111.72534 W Metropolitan Statistical Area (MSA): 6200 Phoenix-Mesa General Information Pollutant O3 Parameter Code 44201 Parameter Occurrence Code 1 Collection Frequency Continuous Analysis Method (filter samples only) Not Applicable Any Proposal to Remove or Move Monitor? No Does monitor operation meet 40 CFR Part 58, Subpart G – Appendices A, Yes C, D, and E? Is site suitable for comparison to the annual PM2.5 NAAQS as per §58.30? Not Applicable Are Data Comparable to Respective NAAQS? Yes Appendix A Requirements - Quality Assurance Requirements for SLAMS and SPMs Number of 1-Point QC (Precision) Checks Performed (Gases) 30 Frequency of 1-Point QC (Precision) Checks Bi-Weekly Number of Flow Rate Verifications Performed (PM) Not Applicable Frequency of Flow Rate Verifications Number of PE Audits Performed 2 02/20/24 Dates of PE Audits 09/04/24 Annual Precision & PE Audit Reports Submitted to AQS? Yes Date of Annual Data Certification Submission 4/30/25 Appendix B Requirements - PSD Monitoring - Not Applicable Appendix C Requirements - Monitoring Methodology Date Sampling Started 04/01/1996 Monitor Type SLAMS Monitor Make – Model Teledyne API – 400T Method Code 087 Method Type (FRM, FEM, ARM) FEM Appendix D Requirements - Network Design Criteria Site Type Population Exposure Basic Monitoring Objective NAAQS Comparison Monitoring Scale (Spatial Scale Represented) Neighborhood Monitoring Season Jan-Dec Network Meets Minimum Number of Monitors Required? Yes Appendix E Requirements - Probe and Monitoring Path Siting Criteria Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 80 FOUNTAIN HILLS Distance between collocated samplers Probe Height (distance above ground level to inlet) Airflow Arc Probe Sample Line Material Pollutant Sample Residence Time (seconds) Not Applicable 4.4 meters 360º FEP 9.01 Distance from Supporting Structure/Roof (horizontal distance and vertical distance to probe/inlet) Horizontal 0.1 meters Vertical 1.8 meters Distance from Obstructions on Roof (horizontal distance to obstruction and vertical height of obstruction above probe/inlet) Distance from Obstructions Not on Roof (horizontal distance to the obstruction and vertical height of obstruction above probe/inlet) Distance from Dripline of Closest Tree(s) Distance to Furnace or Flue Nearest Major Roadway Distance and Direction to Road Average Daily Traffic Count Groundcover Horizontal no obstructions Vertical no obstructions Horizontal 8.2 meters Vertical 0 meters 15 meters No Furnace or Flue Palisades Blvd 70 meters, SW 17,837 Pavement Source: EPA AQS 2024 DQI Report (AMP256); EPA AQS 2024 QA Raw Assessment Report (AMP 251 ) Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 81 Glendale (GL) (04-013-2001) Site Location 59th Ave. & Olive Ave., Glendale Spatial Scale Neighborhood Site Type Population Exposure Site Description: The site began operating in January 1974. This SLAMS location monitors for O3, PM10, and PM2.5. Meteorological monitoring includes ambient temperature, barometric pressure, relative humidity, and wind speed/direction. The site is located on the grounds of Glendale Community College near homes, various strip malls, food establishments, and parks. Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 82 GLENDALE County ID: GL AQS ID: 04-013-2001 Address: 6001 W Olive, Glendale Coordinates: 33.57453 N, -112.19193 W Metropolitan Statistical Area (MSA): 6200 Phoenix-Mesa General Information Pollutant O3 PM10 PM2.5 Parameter Code 44201 81102 88101 Parameter Occurrence Code 1 1 3 Collection Frequency Continuous Continuous Continuous Not Not Not Analysis Method (filter samples only) Applicable Applicable Applicable Any Proposal to Remove or Move Monitor? No No No Does monitor operation meet 40 CFR Part 58, Yes Yes Yes Subpart G – Appendices A, C, D, and E? Is site suitable for comparison to the annual Not Not Yes PM2.5 NAAQS as per §58.30? Applicable Applicable Are Data Comparable to Respective NAAQS? Yes Yes Yes Appendix A Requirements - Quality Assurance Requirements for SLAMS and SPMs Number of 1-Point QC (Precision) Checks 34 Not Not Performed (Gases) Applicable Applicable Frequency of 1-Point QC (Precision) Checks Bi-Weekly Number of Flow Rate Verifications Performed 25 25 Not (PM) Applicable Frequency of Flow Rate Verifications Bi-Weekly Bi-Weekly Number of PE Audits Performed 2 4 4 02/06/24 02/06/24 04/02/24 05/15/24 05/15/24 Dates of PE Audits 10/18/24 08/07/24 08/07/24 10/16/24 10/16/24 Annual Precision & PE Audit Reports Submitted Yes Yes Yes to AQS? Date of Annual Data Certification Submission 4/30/25 Appendix B Requirements - PSD Monitoring - Not Applicable Appendix C Requirements - Monitoring Methodology Date Sampling Started 01/01/1974 07/01/1987 Monitor Type SLAMS SLAMS Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 6/1/2011 SLAMS 83 GLENDALE Teledyne API – 400T Monitor Make - Model Method Code Thermo TEOM 1405DF 208 087 Not PM Monitor Flow Type Low Volume Applicable Not PM Monitor Collection Type Dichotomous Applicable Method Type (FRM, FEM, ARM) FEM FEM Appendix D Requirements - Network Design Criteria Population Population Site Type Exposure Exposure NAAQS NAAQS Basic Monitoring Objective Comparison Comparison Monitoring Scale (Spatial Scale Represented) Neighborhood Neighborhood Monitoring Season Jan-Dec Jan-Dec Network Meets Minimum Number of Monitors Yes Yes Required? Thermo TEOM 1405DF 182 Low Volume Dichotomous FEM Population Exposure NAAQS Comparison Neighborhood Jan-Dec Yes Appendix E Requirements - Probe and Monitoring Path Siting Criteria Distance between collocated samplers Distance between PM10 and PM2.5 monitors Probe Height (distance above ground level to inlet) Airflow Arc Not Applicable Not Applicable Not Applicable Not Applicable 0 meters 0 meters 4.5 meters 4.9 meters 4.9 meters 360º 360º Not Applicable Not Applicable 360º Not Applicable Not Applicable Probe Sample Line Material FEP Pollutant Sample Residence Time (seconds) 9.16 Distance from Supporting Structure/Roof (horizontal distance and vertical distance to probe/inlet) Distance from Obstructions on Roof (horizontal distance to obstruction and vertical height of obstruction above probe/inlet) Distance from Obstructions Not on Roof (horizontal distance to the Horizontal 0.1 meters 0 meters 0 meters Vertical 1.6 meters 2.0 meters 2.0 meters no obstructions no obstructions no obstructions no obstructions no obstructions no obstructions no obstructions no obstructions no obstructions Horizontal Vertical Horizontal Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 84 GLENDALE obstruction and vertical height of obstruction above probe/inlet) Vertical Distance from Dripline of Closest Tree(s) no obstructions no obstructions no obstructions 15.5 meters 18.3 meters 18.3 meters No Furnace or Flue Olive Ave 225 meters, S 25,000 59th Ave 475 meters, E 25,394 Pavement No Furnace or Flue Olive Ave 227 meters, S 25,000 59th Ave 430 meters, E 25,394 Pavement No Furnace or Flue Nearest Major Roadway A Olive Ave Distance and Direction to Road 227 meters, S Average Daily Traffic Count 25,000 Nearest Major Roadway B 59th Ave Distance and Direction to Road 430 meters, E Average Daily Traffic Count 25,394 Groundcover Pavement Source: EPA AQS 2024 DQI Report (AMP256); EPA AQS 2024 QA Raw Assessment Report (AMP 251 ) Distance to Furnace or Flue Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 85 Higley (HI) (04-013-4006) Site Location Higley Rd. & Williams Field Rd., Gilbert Spatial Scale Neighborhood Site Type Population Exposure Site Description: Originally, ADEQ began monitoring at this site in 1994 to measure background particulate concentrations near the urban limits of Maricopa County. The MCAQD assumed operating this site in July 2000. This SLAMS location monitors for PM 10. Meteorological monitoring includes ambient temperature, barometric pressure, and wind speed/direction. The site is in a suburban area near homes, strip malls, and schools with limited agricultural operations nearby. Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 86 HIGLEY County ID: HI AQS ID: 04-013-4006 Address: 2207 S Higley Rd., Gilbert Coordinates: 33.30995 N, -111.72003 W Metropolitan Statistical Area (MSA): 6200 Phoenix-Mesa General Information Pollutant PM10 Parameter Code 81102 Parameter Occurrence Code 1 Collection Frequency Continuous Analysis Method (filter samples only) Not Applicable Any Proposal to Remove or Move Monitor? No Does monitor operation meet 40 CFR Part 58, Subpart G – Appendices A, C, D, Yes and E? Is site suitable for comparison to the annual PM2.5 NAAQS as per §58.30? Not Applicable Are Data Comparable to Respective NAAQS? Yes Appendix A Requirements - Quality Assurance Requirements for SLAMS and SPMs Number of 1-Point QC (Precision) Checks Performed (Gases) Not Applicable Frequency of 1-Point QC (Precision) Checks Number of Flow Rate Verifications Performed (PM) 26 Frequency of Flow Rate Verifications Bi-Weekly Number of PE Audits Performed 4 02/21/24 05/06/24 Dates of PE Audits 08/09/24 11/14/24 Annual Precision & PE Audit Reports Submitted to AQS? Yes Date of Annual Data Certification Submission 4/30/25 Appendix B Requirements - PSD Monitoring - Not Applicable Appendix C Requirements - Monitoring Methodology Date Sampling Started 07/01/2000 Monitor Type SLAMS Thermo – TEOM Monitor Make - Model 1405-S Method Code 079 PM Monitor Flow Type Low Volume PM Monitor Collection Type Size Specific Method Type (FRM, FEM, ARM) FEM Appendix D Requirements - Network Design Criteria Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 87 HIGLEY Population Exposure NAAQS Basic Monitoring Objective Comparison Monitoring Scale (Spatial Scale Represented) Neighborhood Monitoring Season Jan-Dec Network Meets Minimum Number of Monitors Required? Yes Appendix E Requirements - Probe and Monitoring Path Siting Criteria Distance between collocated samplers Not Applicable Probe Height (distance above ground level to inlet) 3.7 meters Airflow Arc 360º Probe Sample Line Material Not Applicable Pollutant Sample Residence Time (seconds) Not Applicable Site Type Distance from Supporting Structure/Roof (horizontal distance and vertical distance to probe/inlet) Distance from Obstructions on Roof (horizontal distance to obstruction and vertical height of obstruction above probe/inlet) Distance from Obstructions Not on Roof (horizontal distance to the obstruction and vertical height of obstruction above probe/inlet) Distance from Dripline of Closest Tree(s) Distance to Furnace or Flue Nearest Major Roadway A Distance and Direction to Road Average Daily Traffic Count Nearest Major Roadway B Distance and Direction to Road Average Daily Traffic Count Groundcover Horizontal 0 meters Vertical Horizontal Vertical Horizontal 0.9 meters no obstructions no obstructions no obstructions Vertical no obstructions 36.6 meters No Furnace or Flue Higley Rd 117 meters, E 18,298 Williams Field Rd 410 meters, S 11,500 Pavement Source: EPA AQS 2024 DQI Report (AMP256); EPA AQS 2024 QA Raw Assessment Report (AMP 251 ) Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 88 Humboldt Mountain (HM) (04-013-9508) Site Location Humboldt Mtn. Summit Spatial Scale Regional Site Type Maximum O3 Concentration Site Description: This site began operating in August 1995. This SLAMS location monitors for O3. Meteorological monitoring includes ambient temperature and relative humidity. The site is located on Federal Aviation Agency (FAA) property within the Tonto National Forest. In 2019, the long-anticipated move of the station into a new facility occurred. The new station is about 15 meters away from the National Forest Service building that once housed it. This site is located approximately 40 miles NE of the Phoenix metropolitan area at an elevation of 5190 feet and represents extreme downwind O 3 concentrations. Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 89 HUMBOLDT MOUNTAIN County ID: HM AQS ID: 04-013-9508 Address: E State Hwy 562- FAA Radar Station, Tonto National Forest Coordinates: 33.98280 N, -111.79871 W Metropolitan Statistical Area (MSA): 6200 Phoenix-Mesa General Information Pollutant O3 Parameter Code 44201 Parameter Occurrence Code 1 Collection Frequency Continuous Analysis Method (filter samples only) Not Applicable Any Proposal to Remove or Move Monitor? No Does monitor operation meet 40 CFR Part 58, Subpart G – Yes Appendices A, C, D, and E? Is site suitable for comparison to the annual PM2.5 NAAQS as per Not Applicable §58.30? Are Data Comparable to Respective NAAQS? Yes Appendix A Requirements - Quality Assurance Requirements for SLAMS and SPMs Number of 1-Point QC (Precision) Checks Performed (Gases) 28 Frequency of 1-Point QC (Precision) Checks Bi-Weekly Number of Flow Rate Verifications Performed (PM) Not Applicable Frequency of Flow Rate Verifications Number of PE Audits Performed 2 04/10/24 Dates of PE Audits 10/01/24 Annual Precision & PE Audit Reports Submitted to AQS? Yes Date of Annual Data Certification Submission 4/30/25 Appendix B Requirements - PSD Monitoring - Not Applicable Appendix C Requirements - Monitoring Methodology Date Sampling Started 08/01/1995 Monitor Type SLAMS Monitor Make – Model Teledyne API – 400T Method Code 087 Method Type (FRM, FEM, ARM) FEM Appendix D Requirements - Network Design Criteria Site Type Maximum O3 Concentration Basic Monitoring Objective NAAQS Comparison Monitoring Scale (Spatial Scale Represented) Regional Monitoring Season Jan-Dec Network Meets Minimum Number of Monitors Required? Yes Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 90 HUMBOLDT MOUNTAIN Appendix E Requirements - Probe and Monitoring Path Siting Criteria Distance between collocated samplers Not Applicable Probe Height (distance above ground level to inlet) 4.4 meters Airflow Arc 360º Probe Sample Line Material FEP Pollutant Sample Residence Time (seconds) 8.96 Distance from Supporting Structure/Roof Horizontal 0.7 meters (horizontal distance and vertical distance to Vertical 1.5 meters probe/inlet) Distance from Obstructions on Roof (horizontal Horizontal no obstruction distance to obstruction and vertical height of Vertical no obstruction obstruction above probe/inlet) Distance from Obstructions Not on Roof Horizontal no obstruction (horizontal distance to the obstruction and vertical Vertical no obstruction height of obstruction above probe/inlet) Distance from Dripline of Closest Tree(s) no tree Distance to Furnace or Flue No Furnace or Flue Nearest Major Roadway - Remote Mountaintop - Access using E. Cave Creek Rd. State Hwy 562 Distance and Direction to Road 15 miles south Average Daily Traffic Count 792 Groundcover Soil / Vegetation Source: EPA AQS 2024 DQI Report (AMP256); EPA AQS 2024 QA Raw Assessment Report (AMP 251 ) Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 91 Mesa (ME) (04-013-1003) Site Location Broadway Rd. & Brooks Ave., Mesa Spatial Scale Neighborhood Site Type Population Exposure Site Description: This site began operating in January 1978. This SLAMS location monitors for CO, O3, PM10, and PM2.5. Meteorological monitoring includes ambient temperature, barometric pressure, relative humidity, and wind speed/direction. The site is located at Mesa Brooks Reservoir, which is an area that contains residential, commercial, and industrial properties. Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 92 MESA County ID: ME AQS ID: 04-013-1003 Address: 310 S Brooks, Mesa Coordinates: 33.41018 N, -111.86536 W Metropolitan Statistical Area (MSA): 6200 Phoenix-Mesa General Information Pollutant CO O3 PM10 PM2.5 Parameter Code 42101 44201 81102 88101 Parameter Occurrence Code 1 1 1 3 Collection Frequency Continuous Continuous Continuous Continuous Analysis Method (filter Not Applicable Not Applicable Not Applicable Not Applicable samples only) Any Proposal to Remove or No No No No Move Monitor? Does monitor operation meet 40 CFR Part 58, Yes Yes Yes Yes Subpart G – Appendices A, C, D, and E? Is site suitable for comparison to the annual Not Applicable Not Applicable Not Applicable Yes PM2.5 NAAQS as per §58.30? Are Data Comparable to Yes Yes Yes Yes Respective NAAQS? Appendix A Requirements - Quality Assurance Requirements for SLAMS and SPMs Number of 1-Point QC (Precision) Checks 30 30 Not Applicable Performed (Gases) Frequency of 1-Point QC Bi-Weekly Bi-Weekly (Precision) Checks Number of Flow Rate Verifications Performed 27 27 (PM) Not Applicable Not Applicable Frequency of Flow Rate Bi-Weekly Bi-Weekly Verifications Number of PE Audits 2 2 4 4 Performed Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 93 MESA Dates of PE Audits 01/05/24 08/06/24 04/25/24 10/15/24 02/15/24 05/24/24 08/06/24 11/08/24 Annual Precision & PE Audit Yes Yes Yes Reports Submitted to AQS? Date of Annual Data 4/28/23 Certification Submission Appendix B Requirements - PSD Monitoring - Not Applicable Appendix C Requirements - Monitoring Methodology Date Sampling Started 01/01/1978 11/1/2012 11/1/2012 Monitor Type SLAMS SLAMS SLAMS Teledyne API – Teledyne API – Thermo - TEOM Monitor Make - Model 300T 400T 1405-DF Method Code 093 087 208 PM Monitor Flow Type Not Applicable Not Applicable Low Volume PM Monitor Collection Type Not Applicable Not Applicable Dichotomous Method Type (FRM, FEM, FRM FEM FEM ARM) Appendix D Requirements - Network Design Criteria Population Population Population Site Type Exposure Exposure Exposure NAAQS NAAQS NAAQS Basic Monitoring Objective Comparison Comparison Comparison Monitoring Scale (Spatial Neighborhood Neighborhood Neighborhood Scale Represented) Monitoring Season Sep-Mar Jan-Dec Jan-Dec Network Meets Minimum Number of Monitors Yes Yes Yes Required? Appendix E Requirements - Probe and Monitoring Path Siting Criteria Distance between collocated Not Applicable Not Applicable Not Applicable samplers Distance between PM10 and Not Applicable Not Applicable 0 meters PM2.5 monitors Probe Height (distance 4.1 meters 4.1 meters 4.7 meters above ground level to inlet) Airflow Arc 360º 360º 360º Probe Sample Line Material FEP FEP Not Applicable Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 02/15/24 05/24/24 08/06/24 11/08/24 Yes 11/1/2012 SLAMS Thermo - TEOM 1405-DF 182 Low Volume Dichotomous FEM Population Exposure NAAQS Comparison Neighborhood Jan-Dec Yes Not Applicable 0 meters 4.7 meters 360º Not Applicable 94 MESA Pollutant Sample Residence Time (seconds) Distance from Horizontal Supporting Structure/Roof (horizontal distance and Vertical vertical distance to probe/inlet) Distance from Horizontal Obstructions on Roof (horizontal distance to obstruction Vertical and vertical height of obstruction above probe/inlet) Distance from Horizontal Obstructions Not on Roof (horizontal distance to the obstruction Vertical and vertical height of obstruction above probe/inlet) Distance from Dripline of Closest Tree(s) Distance to Furnace or Flue Nearest Major Roadway Distance and Direction to Road Average Daily Traffic Count 5.47 8.12 Not Applicable Not Applicable 0 meters 0 meters 0 meters 0 meters 1.5 meters 1.5 meters 2.0 meters 2.0 meters no obstruction no obstruction no obstruction no obstruction no obstruction no obstruction no obstruction no obstruction no obstruction no obstruction no obstruction no obstruction no obstruction no obstruction no obstruction no obstruction no tree no tree no tree no tree No Furnace or Flue Broadway Rd. No Furnace or Flue Broadway Rd. No Furnace or Flue Broadway Rd. No Furnace or Flue Broadway Rd. 305 meters, S 305 meters, S 305 meters, S 305 meters, S 23,465 23,465 23,465 23,465 Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 95 MESA Groundcover Pavement/Gravel Pavement/Gravel Pavement/Gravel Pavement/Gravel Source: EPA AQS 2024 DQI Report (AMP256); EPA AQS 2024 QA Raw Assessment Report (AMP 251 ) Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 96 North Phoenix (NP) (04-013-1004) Site Location 7th St. & Butler Ave., Phoenix Spatial Scale Neighborhood Site Type Population Exposure for PM10 & PM2.5; Max Concentration for O3 Site Description: This site began operating in January 1975. This SLAMS location monitors for O3, and PM10, PM2.5. Meteorological monitoring includes ambient temperature, barometric pressure, and wind speed/direction. Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 97 NORTH PHOENIX County ID: NP AQS ID: 04-013-1004 Address: 601 E Butler Dr., Phoenix Coordinates: 33.56034 N, -112.06627 W Metropolitan Statistical Area (MSA): 6200 Phoenix-Mesa General Information Pollutant O3 PM10 PM2.5 Parameter Code 44201 81102 88101 Parameter Occurrence Code 1 1 3 Collection Frequency Continuous Continuous Continuous Not Not Not Analysis Method (filter samples only) Applicable Applicable Applicable Any Proposal to Remove or Move Monitor? No No No Does monitor operation meet 40 CFR Part 58, Yes Yes Yes Subpart G – Appendices A, C, D, and E? Is site suitable for comparison to the annual PM2.5 Not Not Yes NAAQS as per §58.30? Applicable Applicable Are Data Comparable to Respective NAAQS? Yes Yes Yes Appendix A Requirements - Quality Assurance Requirements for SLAMS and SPMs Number of 1-Point QC (Precision) Checks 31 Not Not Performed (Gases) Applicable Applicable Frequency of 1-Point QC (Precision) Checks Bi-Weekly Number of Flow Rate Verifications Performed 30 30 Not (PM) Applicable Frequency of Flow Rate Verifications Bi-Weekly Bi-Weekly Number of PE Audits Performed 2 4 4 02/14/24 02/14/24 06/04/24 05/08/24 05/08/24 Dates of PE Audits 12/03/24 08/07/24 08/07/24 11/06/24 11/06/24 Annual Precision & PE Audit Reports Submitted to Yes Yes Yes AQS? Date of Annual Data Certification Submission 4/30/25 Appendix B Requirements - PSD Monitoring - Not Applicable Appendix C Requirements - Monitoring Methodology Date Sampling Started 01/01/1975 9/1/2011 Monitor Type SLAMS SLAMS Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 9/1/2011 SLAMS 98 NORTH PHOENIX Thermo TEOM 1405DF 208 Thermo TEOM 1405DF 182 10.37 Not Applicable Not Applicable Horizontal 1.21 meters 0 meters 0 meters Vertical 1.8 meters 2.1 meters 2.1 meters no obstruction no obstruction 610.01 meters no obstruction no obstruction no obstruction no obstruction 4.8 meters 4.8 meters Teledyne API – 400T Monitor Make - Model Method Code 087 Not PM Monitor Flow Type Low Volume Low Volume Applicable Not PM Monitor Collection Type Dichotomous Dichotomous Applicable Method Type (FRM, FEM, ARM) FEM FEM FEM Appendix D Requirements - Network Design Criteria Max Ozone Population Population Site Type Concentration Exposure Exposure NAAQS NAAQS NAAQS Basic Monitoring Objective Comparison Comparison Comparison Monitoring Scale (Spatial Scale Represented) Neighborhood Neighborhood Neighborhood Monitoring Season Jan-Dec Jan-Dec Jan-Dec Network Meets Minimum Number of Monitors Yes Yes Yes Required? Appendix E Requirements - Probe and Monitoring Path Siting Criteria Not Not Not Distance between collocated samplers Applicable Applicable Applicable Not Distance between PM10 and PM2.5 monitors 0 meters 0 meters Applicable Probe Height (distance above ground level to 4.4 meters 4.7 meters 4.7 meters inlet) Airflow Arc 360º 360º 360º Not Not Probe Sample Line Material FEP Applicable Applicable Pollutant Sample Residence Time (seconds) Distance from Supporting Structure/Roof (horizontal distance and vertical distance to probe/inlet) Distance from Obstructions on Roof (horizontal distance to obstruction and vertical height of obstruction above probe/inlet) Distance from Obstructions Not on Roof (horizontal distance to the Horizontal Vertical Horizontal Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 99 NORTH PHOENIX obstruction and vertical height of Vertical obstruction above probe/inlet) Distance from Dripline of Closest Tree(s) 4.5 meters 4.5 meters 13.7 meters No Furnace or Flue 7th St. 75 meters, E 18,298 Gravel 10.1 meters No Furnace or Flue 7th St. 75 meters, E 18,298 Gravel 4.5 meters 10.1 meters No Furnace or Distance to Furnace or Flue Flue Nearest Major Roadway 7th St. Distance and Direction to Road 75 meters, E Average Daily Traffic Count (ADT) 18,298 Groundcover Gravel Source: EPA AQS 2024 DQI Report (AMP256); EPA AQS 2024 QA Raw Assessment Report (AMP 251 ) Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 100 Pinnacle Peak (PP) (04-013-2005) Site Location Alma School & Happy Valley Rd., Scottsdale Spatial Scale Urban Site Type Maximum O3 Concentration Site Description: This site began operating in February 1988. This SLAMS location monitors for O3 only. Meteorological monitoring includes ambient temperature, barometric pressure, relative humidity, and wind speed/direction. The site is located approximately 25 miles NE of the Phoenix metropolitan area and represents maximum O3 concentrations downwind from an urban area. This site measures O 3 concentrations related to the transport of O3 from central metropolitan Phoenix. Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 101 PINNACLE PEAK County ID: PP AQS ID: 04-013-2005 Address: 24301 N Alma School Rd., Scottsdale Coordinates: 33.706315 N, -111.856151 W Metropolitan Statistical Area (MSA): 6200 Phoenix-Mesa General Information Pollutant O3 Parameter Code 44201 Parameter Occurrence Code 1 Collection Frequency Continuous Analysis Method (filter samples only) Not Applicable Any Proposal to Remove or Move Monitor? No Does monitor operation meet 40 CFR Part 58, Subpart G – Appendices Yes A, C, D, and E? Is site suitable for comparison to the annual PM2.5 NAAQS as per Not Applicable §58.30? Are Data Comparable to Respective NAAQS? Yes Appendix A Requirements - Quality Assurance Requirements for SLAMS and SPMs Number of 1-Point QC (Precision) Checks Performed (Gases) 29 Frequency of 1-Point QC (Precision) Checks Bi-Weekly Number of Flow Rate Verifications Performed (PM ) Not Applicable Frequency of Flow Rate Verifications Number of PE Audits Performed 2 01/09/24 Dates of PE Audits 07/15/24 Annual Precision & PE Audit Reports Submitted to AQS? Yes Date of Annual Data Certification Submission 4/30/25 Appendix B Requirements - PSD Monitoring - Not Applicable Appendix C Requirements - Monitoring Methodology Date Sampling Started 02/01/1988 Monitor Type SLAMS Monitor Make - Model Teledyne API – 400T Method Code 087 Method Type (FRM, FEM, ARM) FEM Appendix D Requirements - Network Design Criteria Site Type Max Ozone Concentration Basic Monitoring Objective NAAQS Comparison Monitoring Scale (Spatial Scale Represented) Urban Monitoring Season Jan-Dec Network Meets Minimum Number of Monitors Required? Yes Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 102 PINNACLE PEAK Appendix E Requirements - Probe and Monitoring Path Siting Criteria Distance between collocated samplers Not Applicable Probe Height (distance above ground level to inlet) 4.2 meters Airflow Arc 360º Probe Sample Line Material FEP Pollutant Sample Residence Time (seconds) 5.34 Distance from Supporting Structure/Roof (horizontal distance and vertical distance to probe/inlet) Horizontal 0.1 meters Vertical 1.6 meters Distance from Obstructions on Roof (horizontal distance to obstruction and vertical height of obstruction above probe/inlet) Distance from Obstructions Not on Roof (horizontal distance to the obstruction and vertical height of obstruction above probe/inlet) Distance from Dripline of Closest Tree(s) Distance to Furnace or Flue Nearest Major Roadway Distance and Direction to Road Average Daily Traffic Count Groundcover Horizontal no obstruction Vertical no obstruction Horizontal 21.9 meters 4.3 meters Vertical 37.4 meters No Furnace or Flue Happy Valley Rd. 61 meters, S 16,678 Pavement / Grass Source: EPA AQS 2024 DQI Report (AMP256); EPA AQS 2024 QA Raw Assessment Report (AMP 251 ) Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 103 South Phoenix (SP) (04-013-4003) Site Location Central Ave. & Broadway Rd., Phoenix Spatial Scale Neighborhood Site Type Population Exposure Site Description: The site began operating in October 1999. This SLAMS location monitors for CO, O3, PM10, and PM2.5. Meteorological monitoring includes ambient temperature, barometric pressure, relative humidity, and wind speed/direction. The site borders a mixture of high population density residential and commercial properties. Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 104 SOUTH PHOENIX County ID: SP AQS ID: 04-013-4003 Address: 33 W Tamarisk St., Phoenix Coordinates: 33.40314 N, -112.07526 W Metropolitan Statistical Area (MSA): 6200 Phoenix-Mesa General Information Pollutant CO O3 PM10 PM2.5 Parameter Code 42101 44201 81102 88101 Parameter Occurrence Code 1 1 1 3 Collection Frequency Continuous Continuous Continuous Continuous Analysis Method (filter Not Not Not Not Applicable samples only) Applicable Applicable Applicable Any Proposal to Remove or No No No No Move Monitor? Does monitor operation meet 40 CFR Part 58, Subpart G – Yes Yes Yes Yes Appendices A, C, D, and E? Is site suitable for comparison Not Not to the annual PM2.5 NAAQS as Not Applicable Yes Applicable Applicable per §58.30? Are Data Comparable to Yes Yes Yes Yes Respective NAAQS? Appendix A Requirements - Quality Assurance Requirements for SLAMS and SPMs Number of 1-Point QC (Precision) Checks Performed 31 32 Not Not (Gases) Applicable Applicable Frequency of 1-Point QC Bi-Weekly Bi-Weekly (Precision) Checks Number of Flow Rate 28 28 Verifications Performed (PM) Not Not Applicable Applicable Frequency of Flow Rate Bi-Weekly Bi-Weekly Verifications Number of PE Audits 2 2 4 4 Performed 02/16/24 02/16/24 04/05/24 03/06/24 05/13/24 05/13/24 Dates of PE Audits 11/26/24 10/16/24 08/08/24 08/08/24 11/26/24 11/26/24 Annual Precision & PE Audit Yes Yes Yes Yes Reports Submitted to AQS? Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 105 SOUTH PHOENIX Date of Annual Data Certification Submission 4/30/25 Appendix B Requirements - PSD Monitoring - Not Applicable Appendix C Requirements - Monitoring Methodology Date Sampling Started 10/01/1999 10/01/1999 7/1/2007 05/01/2010 Monitor Type SLAMS SLAMS SLAMS SLAMS Thermo Thermo Teledyne API – Teledyne API Monitor Make - Model TEOM 1405TEOM 1405300T – 400T DF DF Method Code 093 087 208 182 Not PM Monitor Flow Type Not Applicable Low Volume Low Volume Applicable Not PM Monitor Collection Type Not Applicable Dichotomous Dichotomous Applicable Method Type (FRM, FEM, ARM) FRM FEM FEM FEM Appendix D Requirements - Network Design Criteria Population Population Population Population Site Type Exposure Exposure Exposure Exposure NAAQS NAAQS NAAQS NAAQS Basic Monitoring Objective Comparison Comparison Comparison Comparison Monitoring Scale (Spatial Scale Neighborhood Neighborhood Neighborhood Neighborhood Represented) Monitoring Season Jan-Dec Jan-Dec Jan-Dec Jan-Dec Network Meets Minimum Yes Yes Yes Yes Number of Monitors Required? Appendix E Requirements - Probe and Monitoring Path Siting Criteria Distance between collocated Not Not Not Not Applicable samplers Applicable Applicable Applicable Distance between PM10 and Not Not Applicable 0 meters 0 meters PM2.5 monitors Applicable Probe Height (distance above 5.2 meters 5.2 meters 4.2 meters 4.2 meters ground level to inlet) Airflow Arc 360º 360º 360º 360º Probe Sample Line Material FEP FEP Not Applicable Not Applicable Pollutant Sample Residence Time (seconds) 4.37 5.29 Not Applicable Not Applicable Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 106 SOUTH PHOENIX Distance from Horizontal Supporting Structure/Roof (horizontal Vertical distance and vertical distance to probe/inlet) Distance from Horizontal Obstructions on Roof (horizontal distance to obstruction and vertical height of Vertical obstruction above probe/inlet) Distance from Obstructions Not Horizontal on Roof (horizontal distance to the obstruction and vertical height of Vertical obstruction above probe/inlet) Distance from Dripline of Closest Tree(s) 0.3 meters 0.3 meters 0 meters 0 meters 2.0 meters 2.0 meters 3.0 meters 3.0 meters no obstruction no obstruction no obstruction no obstruction no obstruction no obstruction no obstruction no obstruction 21.0 meters 21.0 meters 2.4 meters 2.4 meters 0 meters 0 meters 0.6 meters 0.6 meters 13.2 meters 13.2 meters 8.9 meters* 8.9 meters* No Furnace or Flue Central Ave. 168 meters, E 23,399 Broadway Rd. 385 meters, N 20,051 Pavement No Furnace or Flue Central Ave. 168 meters, E 23,399 Broadway Rd. 385 meters, N 20,051 Pavement No Furnace or Flue Central Ave. 165 meters, E 23,399 Broadway Rd. 385 meters, N 20,051 Pavement No Furnace or Flue Nearest Major Roadway A Central Ave. Distance and Direction to Road 165 meters, E Average Daily Traffic Count 23,399 Nearest Major Roadway B Broadway Rd. Distance and Direction to Road 385 meters, N Average Daily Traffic Count 20,051 Groundcover Pavement Source: EPA AQS 2024 DQI Report (AMP256); EPA AQS 2024 QA Raw Assessment Report (AMP 251 ) Distance to Furnace or Flue * MCAQD is aware that these measurmenets do not meet siting requirements. The trees closest to the monitor inlets are not on MCAQD property. MCAQD is working with property owners to change the situation to move make adjustments to achieve compliance. Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 107 South Scottsdale (SS) (04-013-3003) Site Location Thomas Rd. & Miller Rd., Scottsdale Spatial Scale Neighborhood Site Type Population Exposure Site Description: This site began operating in January 1974. This SLAMS location monitors for O3 and PM10. Meteorological monitoring includes ambient temperature, barometric pressure, relative humidity, and wind speed/direction. The station is in a residential area. Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 108 SOUTH SCOTTSDALE County ID: SS AQS ID: 04-013-3003 Address: 2857 N Miller Rd., Scottsdale Coordinates: 33.47968 N, -111.91711 W Metropolitan Statistical Area (MSA): 6200 Phoenix-Mesa General Information Pollutant O3 PM10 Parameter Code 44201 81102 Parameter Occurrence Code 1 1 Collection Frequency Continuous Continuous Analysis Method (filter samples only) Not Applicable Not Applicable Any Proposal to Remove or Move Monitor? Yes Yes Does monitor operation meet 40 CFR Part 58, Subpart G – Yes Yes Appendices A, C, D, and E? Is site suitable for comparison to the annual PM2.5 NAAQS as Not Applicable Not Applicable per §58.30? Are Data Comparable to Respective NAAQS? Yes Yes Appendix A Requirements - Quality Assurance Requirements for SLAMS and SPMs Number of 1-Point QC (Precision) Checks Performed (Gases) 28 Not Applicable Frequency of 1-Point QC (Precision) Checks Bi-Weekly Number of Flow Rate Verifications Performed (PM) 27 Not Applicable Frequency of Flow Rate Verifications Bi-Weekly Number of PE Audits Performed 2 Dates of PE Audits 01/03/24 08/06/24 Annual Precision & PE Audit Reports Submitted to AQS? Date of Annual Data Certification Submission 4 02/20/24 05/07/24 08/06/24 11/07/24 Yes Yes 4/30/25 Appendix B Requirements - PSD Monitoring - Not Applicable Appendix C Requirements - Monitoring Methodology Date Sampling Started 01/01/1974 Monitor Type SLAMS Teledyne API – Monitor Make - Model 400T Method Code 087 PM Monitor Flow Type Not Applicable PM Monitor Collection Type Not Applicable Method Type (FRM, FEM, ARM) FEM Appendix D Requirements - Network Design Criteria Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 09/01/2012 SLAMS Thermo - TEOM 1405-S 079 Low Volume Size Specific FEM 109 SOUTH SCOTTSDALE Population Population Exposure Exposure NAAQS NAAQS Basic Monitoring Objective Comparison Comparison Monitoring Scale (Spatial Scale Represented) Neighborhood Neighborhood Monitoring Season Jan-Dec Jan-Dec Network Meets Minimum Number of Monitors Required? Yes Yes Appendix E Requirements - Probe and Monitoring Path Siting Criteria Distance between collocated samplers Not Applicable Not Applicable Probe Height (distance above ground level to inlet) 5.1 meters 6.1 meters Airflow Arc 360º 360º Probe Sample Line Material FEP Not Applicable Pollutant Sample Residence Time (seconds) 8.43 Not Applicable Distance from Supporting Structure/Roof Horizontal 0.46 meters 0 meters (horizontal distance and vertical distance to Vertical 1.9 meters 6.1 meters probe/inlet) Distance from Obstructions on Roof (horizontal Horizontal no obstruction no obstruction distance to obstruction and vertical height of no obstruction Vertical no obstruction obstruction above probe/inlet) Distance from Obstructions Not on Roof 24.6 meters Horizontal 16.4 meters (horizontal distance to the obstruction and 0 meters vertical height of obstruction above Vertical 0 meters probe/inlet) Distance from Dripline of Closest Tree(s) 2.8 meters* 8.1 meters* No Furnace or No Furnace or Distance to Furnace or Flue Flue Flue Nearest Major Roadway A Thomas Rd. Thomas Rd. Distance and Direction to Road 66 meters, N 62 meters, N Average Daily Traffic Count 34,583 34,583 Nearest Major Roadway B Miller Rd. Miller Rd. Distance and Direction to Road 32 meters, W 35 meters, W Average Daily Traffic Count 19,590 19,590 Groundcover Pavement Pavement Source: EPA AQS 2024 DQI Report (AMP256); EPA AQS 2024 QA Raw Assessment Report (AMP 251 ) Site Type * MCAQD is aware that these measurmenets do not meet siting requirements. The proposed change to this monitoring location will address the dripline measurement. Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 110 Tempe (TE) (04-013-4005) Site Location Apache Blvd. & College Ave., Tempe Spatial Scale Neighborhood Site Type Population Exposure Site Description: This site began operating in 2000. This SLAMS location monitors for O 3, PM10, and PM2.5. Meteorological monitoring includes ambient temperature, rain, and wind speed/direction. The station is near the ASU Tempe Campus and surrounded by residential homes, high-density residential properties, and a railroad track. Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 111 TEMPE County ID: TE AQS ID: 04-013-4005 Address: 1525 S College Ave., Tempe Coordinates: 33.4123 N, -111.93471 W Metropolitan Statistical Area (MSA): 6200 Phoenix-Mesa General Information Pollutant O3 PM10 PM2.5 Parameter Code 44201 81102 88101 Parameter Occurrence Code 1 1 3 Collection Frequency Continuous Continuous Continuous Not Not Not Analysis Method (filter samples only) Applicable Applicable Applicable Any Proposal to Remove or Move Monitor? No No No Does monitor operation meet 40 CFR Part 58, Subpart G Yes Yes Yes – Appendices A, C, D, and E? Is site suitable for comparison to the annual PM2.5 Not Not Yes NAAQS as per §58.30? Applicable Applicable Are Data Comparable to Respective NAAQS? Yes Yes Yes Appendix A Requirements - Quality Assurance Requirements for SLAMS and SPMs Number of 1-Point QC (Precision) Checks Performed 28 Not Not (Gases) Applicable Applicable Frequency of 1-Point QC (Precision) Checks Bi-Weekly Number of Flow Rate Verifications Performed (PM) 26 26 Not Applicable Frequency of Flow Rate Verifications Bi-Weekly Bi-Weekly Number of PE Audits Performed 2 3 3 02/05/24 02/05/24 05/17/24 Dates of PE Audits 05/16/24 05/16/24 11/08/24 11/08/24 11/08/24 Annual Precision & PE Audit Reports Submitted to Yes Yes Yes AQS? Date of Annual Data Certification Submission 4/30/25 Appendix B Requirements - PSD Monitoring - Not Applicable Appendix C Requirements - Monitoring Methodology Date Sampling Started 07/01/2000 03/01/2012 Monitor Type SLAMS SLAMS Thermo Teledyne Monitor Make - Model TEOM 1405API – 400T DF Method Code 087 208 Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 03/01/2012 SLAMS Thermo TEOM 1405-DF 182 112 TEMPE Not Low Volume Applicable Not Dichotomou PM Monitor Collection Type Applicable s Method Type (FRM, FEM, ARM) FEM FEM Appendix D Requirements - Network Design Criteria Population Population Site Type Exposure Exposure NAAQS NAAQS Basic Monitoring Objective Comparison Comparison Neighborho Neighborho Monitoring Scale (Spatial Scale Represented) od od Monitoring Season Jan-Dec Jan-Dec Network Meets Minimum Number of Monitors Yes Yes Required? Appendix E Requirements - Probe and Monitoring Path Siting Criteria Not Not Distance between collocated samplers Applicable Applicable Not Distance between PM10 and PM2.5 monitors 0 meters Applicable Probe Height (distance above ground level to inlet) 4.2 meters 4.7 meters Airflow Arc 360º 360º Not Probe Sample Line Material FEP Applicable Not Pollutant Sample Residence Time (seconds) 5.89 Applicable Distance from Supporting Structure/Roof Horizontal 0.1 meters 0 meters (horizontal distance and vertical distance Vertical 1.5 meters 2.1 meters to probe/inlet) no no Distance from Obstructions on Roof Horizontal obstruction obstruction (horizontal distance to obstruction and vertical height of obstruction above no no Vertical probe/inlet) obstruction obstruction Distance from Obstructions Not on Roof Horizontal 5.4 meters 8.2 meters (horizontal distance to the obstruction and vertical height of obstruction above Vertical 0 meters 0 meters probe/inlet) Distance from Dripline of Closest Tree(s) 8.9 meters* 6.2 meters* No Furnace No Furnace Distance to Furnace or Flue or Flue or Flue PM Monitor Flow Type Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan Low Volume Dichotomo us FEM Population Exposure NAAQS Comparison Neighborho od Jan-Dec Yes Not Applicable 0 meters 4.7 meters 360º Not Applicable Not Applicable 0 meters 2.1 meters no obstruction no obstruction 8.2 meters 0 meters 6.2 meters* No Furnace or Flue 113 TEMPE Broadway Rd. 370 meters, Distance and Direction to Road S Average Daily Traffic Count 24,184 Groundcover Gravel Source: EPA AQS 2024 DQI Report (AMP256); EPA AQS 2024 QA Raw Assessment Report (AMP251 ) Nearest Major Roadway Broadway Rd. 370 meters, S 24,184 Gravel Broadway Rd. 370 meters, S 24,184 Gravel * MCAQD is aware that these measurmenets do not meet siting requirements. Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 114 Thirty-Third (TT) (04-013-4020) Site Location Interstate-10 & 33rd Ave., Phoenix Spatial Scale Micro Site Type SourceOriented Site Description: This site began operating in September 2015. This SLAMS location monitors for NO2; and temporarily monitored for CO and PM2.5 from January 2020 through February 2021. CO and PM2.5 were removed from the Thirty-Third site and relocated to the new Eastwood site in March 2021. Meteorological monitoring includes ambient temperature, barometric pressure, relative humidity, and wind speed/direction. The site is one of two near-road air monitoring sites and is located on the south side embankment adjacent to the I-10 and oriented on an east-west section of the highway, midway downslope from 33rd Avenue toward the I-10. Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 115 THIRTY-THIRD County ID: TT AQS ID: 04-013-4020 Address: 3248 W Moreland Ave., Phoenix Coordinates: 33.46173 N, -112.12796 W Metropolitan Statistical Area (MSA): 6200 Phoenix-Mesa General Information Pollutant NO2 Parameter Code 42602 Parameter Occurrence Code Collection Frequency Analysis Method (filter samples only) Any Proposal to Remove or Move Monitor? Does monitor operation meet 40 CFR Part 58, Subpart G – Appendices A, C, D, and E? Is site suitable for comparison to the annual PM2.5 NAAQS as per §58.30? 1 Continuous Not Applicable No Are Data Comparable to Respective NAAQS? Yes Yes Not Applicable Appendix A Requirements - Quality Assurance Requirements for SLAMS and SPMs Number of 1-Point QC (Precision) Checks Performed (Gases) 33 Frequency of 1-Point QC (Precision) Checks Bi-Weekly Number of Flow Rate Verifications (PM) Not Applicable Frequency of Flow Rate Verifications Number of PE Audits Performed 1 Dates of PE Audits 05/20/24 Annual Precision & PE Audit Reports Submitted to AQS? Yes 4/30/25 Date of Annual Data Certification Submission Appendix B Requirements - PSD Monitoring - Not Applicable Appendix C Requirements - Monitoring Methodology Date Sampling Started 09/01/2015 Monitor Type SLAMS Monitor Make – Model Thermo 42iQ Method Code 074 Method Type (FRM, FEM, ARM) FRM Appendix D Requirements - Network Design Criteria Site Type Source-Oriented Basic Monitoring Objective NAAQS Comparison Monitoring Scale (Spatial Scale Represented) Micro Monitoring Season Jan-Dec Network Meets Minimum Number of Monitors Required? Yes Appendix E Requirements - Probe and Monitoring Path Siting Criteria Distance between collocated samplers Not Applicable Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 116 THIRTY-THIRD Probe Height (distance above ground level to inlet) Airflow Arc Probe Sample Line Material Pollutant Sample Residence Time (seconds) Horizonal Distance from Supporting Structure/Roof (horizontal distance and vertical distance to probe/inlet) Vertical Distance from Obstructions on Roof (horizontal distance to obstruction and vertical height of obstruction above probe/inlet) Distance from Obstructions Not on Roof (horizontal distance to the obstruction and vertical height of obstruction above probe/inlet) Distance from Dripline of Closest Tree(s) Distance to Furnace or Flue Nearest Major Roadway Distance and Direction to Road Average Daily Traffic Count Groundcover 11.8 meters 360º FEP 15.08 4.5 meters 0 meters Horizonal no obstruction Vertical no obstruction Horizonal no obstruction Vertical no obstruction 18.3 meters No Furnace or Flue I-10 13.5 meters, N 249,514 Gravel Source: EPA AQS 2024 DQI Report (AMP256); EPA AQS 2024 QA Raw Assessment Report (AMP 251 ) Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 117 West 43rd Avenue (WF) (04-013-4009) Site Location 43rd Ave. & Broadway Rd., Phoenix Spatial Scale Middle Site Type Highest Concentration Site Description: This site began operating in April 2002. This SLAMS location monitors for PM10. Meteorological monitoring includes ambient temperature, barometric pressure, and wind speed/direction. The site is located near a combination of heavy industrial operations and residential homes to measure maximum PM10 concentrations. The sources around the site include sand and gravel operations, automobile and metal recycling facilities, landfills, paved and unpaved haul roads, and cement casting. Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 118 WEST 43RD AVENUE County ID: WF AQS ID: 04-013-4009 Address: 3940 W Broadway Rd., Phoenix Coordinates: 33.40635 N, -112.14426 W Metropolitan Statistical Area (MSA): 6200 Phoenix-Mesa General Information Pollutant PM10 Parameter Code 81102 Parameter Occurrence Code 1 Collection Frequency Continuous Analysis Method (filter samples only) Not Applicable Any Proposal to Remove or Move Monitor? No Does monitor operation meet 40 CFR Part 58, Subpart G – Appendices Yes A, C, D, and E? Is site suitable for comparison to the annual PM2.5 NAAQS as per Not Applicable §58.30? Are Data Comparable to Respective NAAQS? Yes Appendix A Requirements - Quality Assurance Requirements for SLAMS and SPMs Number of 1-Point QC (Precision) Checks Performed (Gases) Not Applicable Frequency of 1-Point QC (Precision) Checks Number of Flow Rate Verifications Performed (PM) 24 Frequency of Flow Rate Verifications Bi-Weekly Number of PE Audits Performed 4 03/14/24 06/03/24 Dates of PE Audits 08/08/24 11/05/24 Annual Precision & PE Audit Reports Submitted to AQS? Yes Date of Annual Data Certification Submission 4/30/25 Appendix B Requirements - PSD Monitoring - Not Applicable Appendix C Requirements - Monitoring Methodology Date Sampling Started 04/01/2002 Monitor Type SLAMS Monitor Make – Model Thermo - TEOM 1405-S Method Code 079 PM Monitor Flow Type Low Volume PM Monitor Collection Type Size Specific Method Type (FRM, FEM, ARM) FEM Appendix D Requirements - Network Design Criteria Site Type Highest Concentration Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 119 WEST 43RD AVENUE Basic Monitoring Objective NAAQS Comparison Monitoring Scale (Spatial Scale Represented) Middle Monitoring Season Jan-Dec Network Meets Minimum Number of Monitors Required? Yes Appendix E Requirements - Probe and Monitoring Path Siting Criteria Distance between collocated samplers Not Applicable Probe Height (distance above ground level to inlet) 4.6 meters Airflow Arc 360º Probe Sample Line Material Not Applicable Pollutant Sample Residence Time (seconds) Not Applicable Horizontal 0 meters Distance from Supporting Structure/Roof (horizontal distance and vertical distance to probe/inlet) Vertical 1.9 meters Distance from Obstructions on Roof (horizontal Horizontal no obstruction distance to obstruction and vertical height of Vertical no obstruction obstruction above probe/inlet) Distance from Obstructions Not on Roof (horizontal Horizontal 13.7 meters distance to the obstruction and vertical height of Vertical 0 meters obstruction above probe/inlet) Distance from Dripline of Closest Tree(s) 20.1 meters Distance to Furnace or Flue No Furnace or Flue Broadway Rd. (E of 35th Nearest Major Roadway A Ave.) Distance and Direction to Road 37 meters, S Average Daily Traffic Count 12,501 th 35 Ave. (N. of Broadway Nearest Major Roadway B Rd.) Distance and Direction to Road 1 kilometer, E Average Daily Traffic Count 28,398 Groundcover Gravel Source: EPA AQS 2024 DQI Report (AMP256); EPA AQS 2024 QA Raw Assessment Report (AMP 251 ) Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 120 West Chandler (WC) (04-013-4004) Site Location Frye Rd. & Ellis St., Chandler Spatial Scale Neighborhood Site Type Population Exposure Site Description: This site began operating in January 1995, This SLAMS location monitors for CO, O3, and PM10. Meteorological monitoring includes ambient temperature, barometric pressure, relative humidity, and wind speed/direction. The site is surrounded by residential, agricultural, and heavy industrial operations, such as semiconductor manufacturing plants and liquid air storage. The PM10 monitor’s scale of representativeness was first established as middle scale, but it was changed to neighborhood in June 2019 to better reflect land use currently surrounding the site. Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 121 WEST CHANDLER County ID: WC AQS ID: 04-013-4004 Address: 275 S Ellis, Chandler Coordinates: 33.29896 N, -111.88426 W Metropolitan Statistical Area (MSA): 6200 Phoenix-Mesa General Information Pollutant CO O3 PM10 Parameter Code 42101 44201 81102 Parameter Occurrence Code 1 1 1 Collection Frequency Continuous Continuous Continuous Not Not Analysis Method (filter samples only) Not Applicable Applicable Applicable Any Proposal to Remove or Move Monitor? No No No Does monitor operation meet 40 CFR Part 58, Yes Yes Yes Subpart G – Appendices A, C, D, and E? Is site suitable for comparison to the annual Not Not Not Applicable PM2.5 NAAQS as per §58.30? Applicable Applicable Are Data Comparable to Respective NAAQS? Yes Yes Yes Appendix A Requirements - Quality Assurance Requirements for SLAMS and SPMs Number of 1-Point QC (Precision) Checks 42 30 Not Performed (Gases) Applicable Frequency of 1-Point QC (Precision) Checks Bi-Weekly Bi-Weekly Number of Flow Rate Verifications Performed 25 Not (PM) Not Applicable Applicable Frequency of Flow Rate Verifications Bi-Weekly Number of PE Audits Performed 2 2 4 03/08/24 03/07/24 04/03/24 06/10/24 Dates of PE Audits 09/05/24 09/05/24 09/05/24 12/13/24 Annual Precision & PE Audit Reports Yes Yes Yes Submitted to AQS? 4/30/25 Date of Annual Data Certification Submission Appendix B Requirements - PSD Monitoring - Not Applicable Appendix C Requirements - Monitoring Methodology Date Sampling Started 07/01/2000 07/01/2000 Monitor Type SLAMS SLAMS Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 07/01/2000 SLAMS 122 Monitor Make - Model Method Code WEST CHANDLER Teledyne API – 300T 093 PM Monitor Flow Type Not Applicable PM Monitor Collection Type Not Applicable Method Type (FRM, FEM, ARM) FRM Teledyne API – 400T 087 Not Applicable Not Applicable Thermo – TEOM 1405-S 079 FEM FEM Low Volume Size Specific Appendix D Requirements - Network Design Criteria Population Population Population Site Type Exposure Exposure Exposure NAAQS NAAQS NAAQS Basic Monitoring Objective Comparison Comparison Comparison Monitoring Scale (Spatial Scale Represented) Neighborhood Neighborhood Neighborhood Monitoring Season Jan-Dec Jan-Dec Jan-Dec Network Meets Minimum Number of Monitors Yes Yes Yes Required? Appendix E Requirements - Probe and Monitoring Path Siting Criteria Not Not Distance between collocated samplers Not Applicable Applicable Applicable Probe Height (distance above ground level to 4.5 meters 4.5 meters 4.7 meters inlet) Airflow Arc 360º 360º 360º Not Probe Sample Line Material FEP FEP Applicable Not Pollutant Sample Residence Time (seconds) 4.14 4.24 Applicable Distance from Supporting Horizontal 0.4 meters 0.4 meters 0 meters Structure/Roof (horizontal distance and vertical distance to Vertical 1.4 meters 1.4 meters 1.6 meters probe/inlet) no no Distance from Obstructions on Horizontal no obstruction obstruction obstruction Roof (horizontal distance to obstruction and vertical height of no no Vertical no obstruction obstruction above probe/inlet) obstruction obstruction Distance from Obstructions Not Horizontal 14 meters 14 meters 14 meters on Roof (horizontal distance to the obstruction and vertical height Vertical 3 meters 3 meters 3 meters of obstruction above probe/inlet) Distance from Dripline of Closest Tree(s) 10.0 meters 10.0 meters Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 11.9 meters 123 WEST CHANDLER No Furnace or Distance to Furnace or Flue Flue Nearest Major Roadway A Frye Rd. Distance and Direction to Road 30 meters, S Average Daily Traffic Count 20,494 Pavement / Groundcover Gravel No Furnace or Flue Frye Rd. 30 meters, S 20,494 Pavement / Gravel No Furnace or Flue Frye Rd. 30 meters, S 20,494 Pavement / Gravel Source: EPA AQS 2024 DQI Report (AMP256); EPA AQS 2024 QA Raw Assessment Report (AMP 251 ) Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 124 West Phoenix (WP) (04-013-0019) Site Location 39th Ave. & Earll Dr., Phoenix Spatial Scale Neighborhood Site Type Population Exposure for CO, NO2, O3, PM10, and Highest Concentration for PM2.5 Site Description: This site began operating in January 1984. This SLAMS location monitors for CO, NO2, O3, PM10, and PM2.5. Meteorological monitoring includes ambient temperature, barometric pressure, and wind speed/direction. The site is in an area of stable, high-density, residential properties. This is the QA collocation site for PM 2.5 where one filter based PM2.5 FRM sampler operates alongside a continuous PM2.5 FEM analyzer as per 40 CFR Part 58 Appendix A. Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 125 Pollutant WEST PHOENIX County ID: WP AQS ID: 04-013-0019 Address: 3847 W Earll, Phoenix Coordinates: 33.48378 N, -112.14256 W Metropolitan Statistical Area (MSA): 6200 Phoenix-Mesa General Information CO NO2 O3 PM10 Parameter Code 42101 42602 44201 81102 PM2.5 Primary 88101 Parameter Occurrence Code 1 1 1 1 3 2 Collection Frequency Continuous Continuous Continuous Continuous Continuous 1 in 12 days Analysis Method (filter samples only) Not Applicable Not Applicable Not Applicable Not Applicable Not Applicable Analytical Laboratory (filter samples only) Not Applicable Not Applicable Not Applicable Not Applicable Not Applicable Any Proposal to Remove or Move Monitor? No No No No No As per 40 CFR Part 50, Appendix L Pace Analytical® IML Air Science Laboratory No Does monitor operation meet 40 CFR Part 58, Subpart G – Appendices A, C, D, and E? Is site suitable for comparison to the annual Yes Yes Yes Yes Yes Yes Not Applicable Not Applicable Not Applicable Not Applicable Yes Yes Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 126 PM2.5 Secondary 88101 PM2.5 NAAQS as per §58.30? Are Data Comparable to Respective NAAQS? Yes Yes Yes Yes Yes Appendix A Requirements - Quality Assurance Requirements for SLAMS and SPMs Number of 1-Point QC 43 35 31 Not Not (Precision) Checks Applicable Applicable Performed (Gases) Frequency of 1-Point QC Bi-Weekly Bi-Weekly Bi-Weekly (Precision) Checks Number of Flow Rate Not Not Not 25 25 Verifications Performed Applicable Applicable Applicable (PM) Frequency of Flow Rate Bi-Weekly Bi-Weekly Verifications Number of Required Not Not Not Not 30 Collocated Assessments Applicable Applicable Applicable Applicable (PM2.5 Only) Number of Valid Not Not Not Not 30 Collocation Assessments Applicable Applicable Applicable Applicable (PM2.5 Only) Number of Collocation Not Not Not Not 30 Assessments in 2021 Applicable Applicable Applicable Applicable (PM2.5 Only) Number of PE Audits 2 2 2 4 4 Performed in 2021 Dates of PE Audits 06/04/24 03/13/24 01/03/24 03/11/24 03/11/24 12/04/24 09/10/24 07/15/24 06/04/24 06/04/24 09/10/24 09/10/24 12/12/24 12/12/24 Annual Precision & PE Audit Yes Yes Yes Yes Yes Reports Submitted to AQS? Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 127 Yes Not Applicable 11 Monthly 4 03/11/24 06/19/24 09/10/24 12/12/24 Yes Date of Annual Data Certification Submission 04/30/25 Appendix B Requirements - PSD Monitoring - Not Applicable Appendix C Requirements - Monitoring Methodology Date Sampling Started Monitor Type Monitor Make - Model 01/01/1984 SLAMS Thermo 48iq *Teledyne API 300T 05/24/1990 SLAMS Thermo 42iq *Teledyne API 200T 01/01/1984 SLAMS Thermo 49iq *Teledyne API 400T 02/01/1988 SLAMS Thermo TEOM 1405DF 09/01/2005 SLAMS Thermo TEOM 1405DF 06/13/2000 SLAMS Thermo Partisol 2025 Notes: The same monitor collects PM10 and PM2.5 hourly (continuous) measurements. The collocated Partisol 2025i sampler collects a QA filter sample once every 12 days. * The gaseous Thermo Scientific instruments at the West Phoenix monitoring site were replaced with Teledyne gaseous instruments on 12 June 2024 following a colocation study. Both sets of instruments were used to collect validated ambient AQ data throughout the year of 2024. There are no plans to return to using Thermo Scientific gaseous instruments on the MCAQD network. Method Code PM Monitor Flow Type PM Monitor Collection Type Method Type (FRM, FEM, ARM) Site Type Basic Monitoring Objective Monitoring Scale (Spatial Scale Represented) Monitoring Season 54 *93 Not Applicable Not Applicable FRM 74 *99 Not Applicable Not Applicable FRM 47 *87 Not Applicable Not Applicable FEM 208 182 145 Low Volume Low Volume Low Volume Dichotomous Dichotomous FEM FEM Size Specific & Sequential FRM Highest Concentration NAAQS Comparison Neighborhood Highest Concentration NAAQS Comparison Neighborhood Jan-Dec Jan-Dec Appendix D Requirements - Network Design Criteria Highest Population Population Population Concentration Exposure Exposure Exposure NAAQS NAAQS NAAQS NAAQS Comparison Comparison Comparison Comparison Neighborhood Neighborhood Neighborhood Neighborhood Jan-Dec Jan-Dec Jan-Dec Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan Jan-Dec 128 Network Meets Minimum Number of Monitors Required? Yes Yes Yes Yes Yes Appendix E Requirements - Probe and Monitoring Path Siting Criteria Distance between Not Not Not 2 meters 2 meters collocated PM2.5 monitors Applicable Applicable Applicable Distance between PM10 and Not Not Not 0 meters 0 meters PM2.5 monitors Applicable Applicable Applicable Probe Height (distance 4.3 meters 4.3 meters 4.3 meters 4.1 meters 4.1 meters above ground level to inlet) Airflow Arc 360º 360º 360º 360º 360º Probe Sample Line FEP FEP FEP Not Not Material Applicable Applicable Pollutant Sample 8.67 8.67 8.67 Not Not Residence Time (seconds) Applicable Applicable Filter Sample Material Not Not Not Not Not Applicable Applicable Applicable Applicable Applicable Distance from Horizontal 0.2 meters 0.2 meters 0.2 meters 1.2 meters 1.2 meters Supporting Vertical 1.5 meters 1.5 meters 1.5 meters 0.6 meters 0.6 meters Structure/Roof (horizontal distance and vertical distance to probe/inlet) Distance from Horizontal no no no no no Obstructions obstruction obstruction obstruction obstruction obstruction on Roof Vertical no no no no no (horizontal obstruction obstruction obstruction obstruction obstruction distance to obstruction and vertical height of obstruction Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 129 Yes 2 meters 2 meters 4.0 meters 360º FEP Not Applicable FEP 0.5 meters 0.5 meters no obstruction no obstruction above probe/inlet) Distance from Horizontal Obstructions Not on Roof Vertical (horizontal distance to the obstruction and vertical height of obstruction above probe/inlet) Distance from Dripline of Closest Tree(s) Distance to Furnace or Flue Nearest Major Roadway Distance and Direction to Road Average Daily Traffic Count Groundcover no obstruction no obstruction no obstruction no obstruction no obstruction no obstruction no obstruction no obstruction no obstruction no obstruction no obstruction no obstruction no tree no tree no tree no tree no tree no tree No Furnace or Flue Thomas Rd. 360 meters, S No Furnace or Flue Thomas Rd. 360 meters, S No Furnace or Flue Thomas Rd. 360 meters, S No Furnace or Flue Thomas Rd. 360 meters, S No Furnace or Flue Thomas Rd. 360 meters, S No Furnace or Flue Thomas Rd. 360 meters, S 29,000 Gravel 29,000 Gravel 29,000 Gravel 29,000 Gravel 29,000 Gravel 29,000 Gravel Source: EPA AQS 2024 DQI Report (AMP256); EPA AQS 2024 QA Raw Assessment Report (AMP 251) Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 130 Zuni Hills (ZH) (04-013-4016) Site Location 109th Ave. & Deer Valley Rd., Phoenix Spatial Scale Neighborhood Site Type Population Exposure Site Description: This site began operating in December 2009. This SLAMS location monitors for PM10. Meteorological monitoring includes ambient temperature and wind speed/direction. The station is located on the campus of the Zuni Hills Elementary School. Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 131 ZUNI HILLS County ID: ZH AQS ID: 04-013-4016 Address: 10851 W Williams Rd., Sun City Coordinates: 33.68719 N, -112.29416 W Metropolitan Statistical Area (MSA): 6200 Phoenix-Mesa General Information Pollutant PM10 Parameter Code 81102 Parameter Occurrence Code 1 Collection Frequency Continuous Analysis Method (filter samples only) Not Applicable Any Proposal to Remove or Move Monitor? No Does monitor operation meet 40 CFR Part 58, Subpart G – Appendices A, Yes C, D, and E? Is site suitable for comparison to the annual PM2.5 NAAQS as per Not Applicable §58.30? Are Data Comparable to Respective NAAQS? Yes Appendix A Requirements - Quality Assurance Requirements for SLAMS and SPMs Number of 1-Point QC (Precision) Checks Performed (Gases) Not Applicable Frequency of 1-Point QC (Precision) Checks Number of Flow Rate Verifications Performed (PM) 24 Frequency of Flow Rate Verifications Bi-Weekly Number of PE Audits Performed 3 06/11/24 Dates of PE Audits 09/04/24 12/11/24 Annual Precision & PE Audit Reports Submitted to AQS? Yes Date of Annual Data Certification Submission 4/30/25 Appendix B Requirements - PSD Monitoring - Not Applicable Appendix C Requirements - Monitoring Methodology Date Sampling Started 12/01/2009 Monitor Type SLAMS Monitor Make – Model Thermo - TEOM 1405-S Method Code 079 PM Monitor Flow Type Low Volume PM Monitor Collection Type Size Specific Method Type (FRM, FEM, ARM) FEM Appendix D Requirements - Network Design Criteria Site Type Population Exposure Basic Monitoring Objective NAAQS Comparison Monitoring Scale (Spatial Scale Represented) Neighborhood Monitoring Season Jan-Dec Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 132 ZUNI HILLS Network Meets Minimum Number of Monitors Required? Yes Appendix E Requirements - Probe and Monitoring Path Siting Criteria Distance between collocated samplers Not Applicable Probe Height (distance above ground level to inlet) 2.9 meters Airflow Arc 360º Probe Sample Line Material Not Applicable Pollutant Sample Residence Time (seconds) Not Applicable Horizontal 0 meters Distance from Supporting Structure/Roof (horizontal distance and vertical distance to probe/inlet) Vertical 0.6 meters no Horizontal obstructions Distance from Obstructions on Roof (horizontal distance to obstruction and vertical height of obstruction above probe/inlet) no Vertical obstructions Horizontal 14 meters Distance from Obstructions Not on Roof (horizontal distance to the obstruction and vertical height of obstruction above probe/inlet) Vertical 17 meters Distance from Dripline of Closest Tree(s) 27.4 meters Distance to Furnace or Flue No Furnace or Flue Nearest Major Roadway 107th Ave. Distance and Direction to Road 200 meters, E Average Daily Traffic Count 12,676 Groundcover Lawn / Soil Source: EPA AQS 2024 DQI Report (AMP256); EPA AQS 2024 QA Raw Assessment Report (AMP 251 ) Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 133 Appendix II - Public Notice and Comment Information Figure 16 shows the public comment period announcement, which appeared in The Record Reporter on May 21st and May 28th, 2025. The public comment period was from May 22nd, 2024, to June 21st, 2025. Additionally, the public notice was posted on the Maricopa County Air Quality Department website at Maricopa.Gov/1624. Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 134 2025 Public Comment Period Announcement Figure 16 Public Comment Period Announcement Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 135 Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 136 A link to join the virtual June 3rd, 2025 Public Comment Meeting via Microsoft Teams is below. Join the meeting now Public Meeting Attendance – June 3rd Attendance to the virtual open forum meeting will be taken by AJ Mesko in lieu of a sign-in sheet, and a list of attendees has been added in Table 26. Table 26 2025 Open Forum Meeting Attendees Name Agency AJ Mesko Maricopa County Air Quality Department Eric Poole Maricopa County Air Quality Department Karen Brown Maricopa County Air Quality Department Ceresa Stewart Maricopa County Air Quality Department Hirna Patel Maricopa County Air Quality Department Karla Copeland Maricopa County Air Quality Department Public Comments Received and MCAQD Responses As stated in the announcement, the open forum meeting provides an opportunity for members of the public and air monitoring community to discuss the County’s air monitoring network. No comments were received by MCAQD during the public comment period which ran from May 22 – June 21, 2025. Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 137 Appendix III - Glossary Glossary of Acronyms and Terms ADEQ: Arizona Department of Environmental Quality AADT: annual average daily traffic count aka: Also known as AMD: Air Monitoring Division AMNP: Air Monitoring Network Plan - an annual report produced for U.S. EPA each calendar year that provides comprehensive information regarding the performance of the County’s air quality surveillance system, e.g., network of SLAMS and SPM monitoring stations and / or sites, and the data collected and reported to EPA. The plan includes proposed future changes to the system as well. Analysis Method Refers to the laboratory method used to process and analyze PM and Pb filter samples. Analyzer: A monitor that samples the air and produces real-time data without collecting a sample that must be laboratory analyzed. ANSI: American National Standards Institute AQI: Air Quality Index - the index that applies to each criteria pollutant and shows the concentration of each pollutant relative to its respective standard. When the AQI reaches 101, the pollutant’s concentration has exceeded the NAAQS. AQS: Air Quality System, sometimes defined as the Air Quality Subsystem. The AQS is the U.S. EPA’s ambient air database. ASQ: American Society for Quality Attainment: Attainment refers to a geographical area as being “in compliance” with a NAAQS and the U.S. Clean Air Act. After several years of no violations of a NAAQS, the U.S. EPA can Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 138 classify a geographic area as in attainment for a particular Criteria Pollutant. AWT: Average Weekday Traffic count BAM: Beta Attenuation Monitor. A continuous particulate measuring instrument used previously by MCAQD to measure PM10. CAA: Clean Air Act CASAC: Clean Air Scientific Advisory Committee CBSA: Core-Based Statistical Area – is defined by the U.S. Office of Management and Budget as a statistical geographic entity consisting of the county or counties associated with at least one urbanized area/urban cluster of at least 10,000 in population, plus adjacent counties having a high degree of social and economic integration. CFR: The Code of Federal Regulations is published annually and contains the codification of the general and permanent rules published in the Federal Register by the executive departments and agencies of the Federal Government. An eCFR is a free electronic version; however, it is not the legal version. Class I Area: Federally designated areas of special national or regional scenic, recreational, or historic value where maximum protection of environmental quality is highest. Class 1 areas are subject to special protection including mandated visibility requirements to prevent significant deterioration. CO: Carbon monoxide, a criteria pollutant Collocated: The practice of establishing a second pollutant monitor within a specified distance and of a specified type at a monitoring site for quality assurance purposes. Continuous Monitor: A method of monitoring air pollutants that is continually measuring the quantity of the pollutant, either gaseous or particulate. Continuous monitors are analyzers that can obtain real-time or short-term averages of pollutants. Continuous monitors may also be referred to as “automated” monitors. Criteria Pollutants: Six pollutants (CO, O 3, NO2, Pb, PM, and SO2) that have NAAQS established by the U.S. EPA. Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 139 CSA: Combined Statistical Area - is defined by the U.S. Office of Management and Budget as when very large cities combine two or more CBSAs, these larger areas are referred to as combined statistical areas CSN: The chemical speciation network - a nationwide, research air monitoring network designed to ferret-out the chemical constitutes of and to discern trends in PM2.5 pollution. This program is managed by the U.S. EPA OAQPS. Delta T: The difference between two levels of temperature measurements - Delta T is measured in the MCAQD network at heights of 2 and 10 meters. A higher temperature at the upper level indicates a temperature inversion. Design Value: A design value is a statistic that describes the air quality status of a given area relative to the level of the NAAQS. For a concentration-based standard, the air quality design value is simply the standard-related test statistic. The design value of a pollutant monitoring network is the highest sample value in the network used to compare to the NAAQS; i.e., the 24-hour PM 2.5 design value for the network is the monitor with the highest 3year average of the 98th percentile. Distance from Obstructions Not on Roof: Means the horizontal distance and vertical height in meters from obstructions such as trees, walls, etc. that are higher than the sample probe/inlet. Distance from Obstructions on Roof: Means the horizontal distance and vertical height in meters from obstructions on a roof such as a parapets, penthouses, and firewalls to the sample probe/inlet. Distance from Supporting Structure: Means the horizontal distance and vertical height in meters from a building or shelter roof to the sample probe/inlet. A roof supports all monitors; whether it be the roof of a building, trailer (room/shelter), or monitor housing cabinet. EBAM: E-Beta Attenuation Monitor - is a rugged, portable, battery or solar-operated analyzer that is suitable for obtaining and reporting continuous measurements of particulate matter in remote locations. EBAMs are often equipped with wind speed and direction instrumentation as well. EBAMs are particularly useful for temporary measurements of PM related to an event. EPA R9: Environmental Protection Agency Region 9 Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 140 EE: Exceptional Event – a high pollution event that is considered to be uncontrollable and caused by natural sources of pollution or an event that is not expected to recur at a given location. An EE can apply to any Criteria Pollutant. Event: Generally, refers to a high pollution day where a NAAQS was exceeded. Exceedance: Generally, refers to a high pollution day where a NAAQS was exceeded. FDMS-TEOM: Filter Dynamics Measurement System-Tapered Element Oscillating Microbalance - a continuous particulate analyzer used by MCAQD to measure PM2.5. FEM: Federal Equivalent Method - an EPA-approved method of sampling and analyzing the ambient air for an air pollutant, i.e., includes the monitor and its operating firmware and procedure(s). An FEM must pass required testing found in 40 CFR Part 53 and show pollutant data produced are similar to the Federal Reference Method (FRM). Continuous particulate matter and some gaseous analyzers are FEMs. Filter-based sampler: A method of monitoring particulate pollution that involves exposing a pre-weighed filter to a specific flow rate for a prescribed period of time, usually midnight-to-midnight, or 1440 minutes. The filters are then post-weighed to determine the mass of particulates per volume, e.g., µg/m3. Filter samples are stored for a period and can be referenced later if needed. FRM: Federal Reference Method - an EPA-approved method of sampling and/or analyzing the ambient air for an air pollutant, i.e., includes the monitor and its operating firmware and procedure(s). An FRM must pass required testing found in 40 CFR Part 53 and show data produced are accurate based on acceptable precision and bias limits. These methods are the baseline that all other methods reference, e.g., Federal Equivalency Methods (FEM). HAPs: Hazardous Air Pollutants - airborne chemicals that are been listed in the federal Clean Air Act and have an associated standard or process requirement determined for it. Sample Probe/Inlet Height: Means the vertical height in meters above the roof, or additional supporting structure on top of the roof if present, to the air sample intake. In general, gas samples enter through a probe at the end of the sample line and PM and Pb samples enter through Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 141 an inlet that helps control the aerodynamic size of particles sampled. MAG: Maricopa Association of Governments MCAQCED: Maricopa County Air Quality Compliance and Enforcement Division MCAQD: Maricopa County Air Quality Department Metadata: refers to data that provide information about other data; and typically includes geospatial and non-geospatial information. See EPA Metadata Specifications MO: Monitoring organization Monitor: Monitor is a term that refers to an instrument, sampler, analyzer, or other device that measures or assists in the measurement of atmospheric air pollutants and which is acceptable for use in ambient air surveillance under the applicable provisions of 40 CFR Part 58 Appendix C. µg/m3: micrograms per cubic meter µm: micrometers MSA: Metropolitan Statistical Area is designated by the U.S. Office of Management and Budget as a geographical area based on the concept of a core area with a large population nucleus, plus adjacent communities having a high degree of economic and social integration within that core. Metropolitan and micropolitan statistical areas are the two categories of CBSAs. Metropolitan areas have populations greater than 50,000, and micropolitan areas have populations between 10,000 and 50,000. The MCAQD operates air monitoring stations within the Phoenix-Mesa MSA, which includes portions of Maricopa and Pinal County. NAAQS: National Ambient Air Quality Standards - health and welfarebased standards established by the U.S. EPA that set permissible airborne concentration levels for the Criteria Pollutants. NATTS: National Air Toxics Trend Stations - a nationwide, research air monitoring program designed to measure toxic air pollutant trends. This program is managed by the U.S. EPA OAQPS. Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 142 NCore: National Core multi-pollutant is a national network of multipollutant monitoring sites used to represent the nation as a whole. There are currently ~75 NCore sites, 1 to 3 per state plus Washington D.C., Virgin Islands, and Puerto Rico located in both urban and rural areas. This program is managed by the U.S. EPA OAQPS. Network: All stations of a given type or types NO2: Nitrogen dioxide. The indicator compound used to gauge the ambient concentration of NOx. NOX: Nitrogen oxide(s), a criteria pollutant. NO x is the sum of nitric oxide (NO), NO2, and other nitrogen-containing compounds. Nonattainment: Means a geographical area is “not in compliance” with the NAAQS and the U.S. Clean Air Act. After several years of violating a NAAQS, the EPA can classify a geographic area as being in nonattainment for a particular criteria pollutant. O3: Ozone, a criteria pollutant OAQPS: The U.S. EPA Office of Air Quality Planning and Standards, located in Research Triangle Park, N.C., which serves as EPA “Headquarters” for ambient air monitoring guidance and the NAAQS reviews. PAMS: Photochemical Ambient Monitoring Stations - a nationwide, research air monitoring program designed to measure specific airborne chemicals that are known to be “precursor pollutants” that form ozone when combined with ultraviolet light and heat. This program is managed by the U.S. EPA OAQPS. PCAQCD: Pinal County Air Quality Control District Pb: Lead, a criteria pollutant Performance Evaluation (PE) Audit: Quality Assurance audits performed on pollutant monitors. PM: Particulate matter, also known as “particulates”, project manager, or preventative maintenance depending on context PM2.5: Particulate matter 2.5 micrometers in aerometric diameter or smaller, a criteria pollutant. PM2.5 is also referred to as “fine” particulate matter. Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 143 PM10: Particulate matter 10 micrometers in aerometric diameter or smaller, a criteria pollutant PM10-2.5 and / or PMc: “Coarse” particulate matter is less than 10 micrometers, but recently, has come to mean PM10 minus PM2.5, not currently regulated as a lone criteria pollutant. ppb: parts per billion ppm: parts per million PQAO: Primary quality assurance organization - a monitoring organization (MO) or other organization that is responsible for a set of air monitoring stations that monitor the same pollutant and for which data quality assessments can be pooled. Each criteria pollutant sampler/monitor at a monitoring station in the SLAMS and SPM networks must be associated with one, and only one, primary quality assurance organization. Primary Standard: The portion of the NAAQS designed to protect public health. Probe: The end of a sample line where a gas sample is extracted from the atmosphere for delivery to a point analyzer for pollutant analysis Probe/Inlet Height: The vertical height in meters above ground level to the air sample intake location for an analyzer or sampler Probe (Sample) Line Material: Refers to the chemical composition of the sample line tubbing. QA: Quality Assurance – generally refers to the administrative or managerial processes in place to verify that quality control activities are successfully carried out by personnel and that data produced meet specified quality requirements prior to use, i.e., written guidance documents, program oversight activities, etc. QC: Quality Control – generally refers to the technical activities in place to produce high quality data, i.e., air monitoring instruments operate within specified criteria, data collection from sites, etc. Quality System: The overall system of technical activities that measure the attributes and performance of a process, item, or service against defined standards to verify that they meet the stated Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 144 requirements established by the customer. (see ANSI/ASQ E42004) Rapid Response: Rapid Response Notification System - a communication tool used by MCAQD to manage high-pollution events by alerting residents, intergovernmental personnel, and stakeholders of increasing PM concentrations. Sampler: A type of air monitor that collects a physical sample for analysis. Air samples may be collected onto a filter, cartridge, or other medium, or into a device such as a canister. Sample Residence Time: This measurement applies to CO, NO2, O3, and SO2 sample lines and it means the amount of time in seconds that it takes for a sample of air to travel from the probe intake to the bulkhead of the point analyzer. EPA recommends a residence time of 10 seconds, but 20 seconds is the maximum allowable. Secondary Standard: The portion of the NAAQS designed to protect public welfare and the environment. SIP: State Implementation Plan - a SIP is a plan produced by state and/or local regulatory agencies that specifies obligations that will be taken for a geographic area in nonattainment to meet the NAAQS for a criteria pollutant. SIPs are also developed for maintaining compliance with the NAAQS. Site: A site is a geographic location. One or more air monitoring stations can be located at a site. SLAMS: State and Local Air Monitoring Station - the SLAMS network consists of approximately 5,000 monitoring stations nationwide whose size and distribution is largely determined by the needs of State and local air pollution control agencies to meet their respective SIP requirements. Other types of monitoring stations include: NCore (national core) and SPM (special purpose). SO2: Sulfur dioxide, a criteria pollutant SPM: Special Purpose Monitor - a special purpose monitor provides data for special studies needed by the State and local agencies to support SIPs and other air program activities. The SPMs are not permanently established as part of a particular pollutant’s Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 145 monitoring station(s); their location can be adjusted easily to accommodate changing needs and priorities. SSI: Size Selective Inlet - the inlet used on high- and low-volume particulate samplers and analyzers to determine the size of particles sampled or measured by the monitor. The particle size separation process usually employs impaction, filtration, or cyclonic flow. Station: A station may comprise a single pollutant monitor, or a group of monitors with a shared objective, located at a particular site. TEOM: Tapered Element Oscillating Microbalance - an automated, continuous FEM PM analyzer used by MCAQD to measure PM 10 and/or PM2.5 concentrations, depending upon the instrument model and air sample inlet configuration(s). tpy: tons per year UATMP: Urban Air Toxics Monitoring Program - a nationwide research air monitoring program designed to measure toxic air pollutants within urban areas. This program is managed by the U.S. EPA OAQPS. U.S. EPA: United States Environmental Protection Agency VOC: Volatile Organic Compound - VOCs are chemical compounds that can easily vaporize and enter the atmosphere. There are many natural and artificial sources of VOCs; solvents and gasoline make up some of the largest artificial sources. VOCs will react with NOx in the presence of sunlight to create groundlevel O3 pollution. Volume: The amount of air sampled for analysis. Volume is calculated by multiplying a monitor’s flowrate by the collection time, usually in minutes. Volume = flowrate X minutes The amount of data in a file or database. Maricopa County  Air Quality Department  2025 Annual Monitoring Network Plan 146