EnviroNearby

Maricopa County, Arizona air quality history

Daily Air Quality Index summaries from EPA monitors in Maricopa, Arizona, 1980–2025.

9%
Good days in 2025
73
Median daily AQI, 2025
38
Days above 100 in 2025
365
Days with an AQI in 2025 (of 365)

In 2025, EPA reported a daily Air Quality Index (AQI) for Maricopa, Arizona on 365 days. 32 of those days (9%) were in the Good range, and the median daily AQI was 73. That median is higher than the typical monitored county in Arizona (median 47 across 13 counties), and higher than the typical monitored U.S. county (40). The main pollutant was ozone on 170 days. Across the years with fuller monitoring, the share of Good days fell: an average of 23% in 1980–1982 versus 10% in 2023–2025.

How the days broke down each year

Each bar is one year. The colored segments show the share of monitored days that fell in each AQI category.

Share of monitored days in each AQI category, by year0%25%50%75%100%1980: Good 91 of 363 days1980: Moderate 167 of 363 days1980: Unhealthy for Sensitive Groups 74 of 363 days1980: Unhealthy 24 of 363 days1980: Very Unhealthy 7 of 363 days19801981: Good 63 of 365 days1981: Moderate 180 of 365 days1981: Unhealthy for Sensitive Groups 78 of 365 days1981: Unhealthy 29 of 365 days1981: Very Unhealthy 15 of 365 days1982: Good 94 of 365 days1982: Moderate 181 of 365 days1982: Unhealthy for Sensitive Groups 62 of 365 days1982: Unhealthy 21 of 365 days1982: Very Unhealthy 7 of 365 days1983: Good 89 of 365 days1983: Moderate 164 of 365 days1983: Unhealthy for Sensitive Groups 61 of 365 days1983: Unhealthy 42 of 365 days1983: Very Unhealthy 9 of 365 days1984: Good 35 of 366 days1984: Moderate 162 of 366 days1984: Unhealthy for Sensitive Groups 107 of 366 days1984: Unhealthy 56 of 366 days1984: Very Unhealthy 6 of 366 days1985: Good 42 of 365 days1985: Moderate 182 of 365 days1985: Unhealthy for Sensitive Groups 103 of 365 days1985: Unhealthy 30 of 365 days1985: Very Unhealthy 8 of 365 days19851986: Good 48 of 365 days1986: Moderate 207 of 365 days1986: Unhealthy for Sensitive Groups 90 of 365 days1986: Unhealthy 18 of 365 days1986: Very Unhealthy 2 of 365 days1987: Good 66 of 363 days1987: Moderate 217 of 363 days1987: Unhealthy for Sensitive Groups 74 of 363 days1987: Unhealthy 6 of 363 days1988: Good 88 of 366 days1988: Moderate 197 of 366 days1988: Unhealthy for Sensitive Groups 73 of 366 days1988: Unhealthy 8 of 366 days1989: Good 89 of 365 days1989: Moderate 198 of 365 days1989: Unhealthy for Sensitive Groups 72 of 365 days1989: Unhealthy 6 of 365 days1990: Good 102 of 365 days1990: Moderate 204 of 365 days1990: Unhealthy for Sensitive Groups 44 of 365 days1990: Unhealthy 15 of 365 days19901991: Good 97 of 365 days1991: Moderate 210 of 365 days1991: Unhealthy for Sensitive Groups 50 of 365 days1991: Unhealthy 8 of 365 days1992: Good 80 of 366 days1992: Moderate 206 of 366 days1992: Unhealthy for Sensitive Groups 65 of 366 days1992: Unhealthy 14 of 366 days1992: Very Unhealthy 1 of 366 days1993: Good 101 of 365 days1993: Moderate 193 of 365 days1993: Unhealthy for Sensitive Groups 51 of 365 days1993: Unhealthy 20 of 365 days1994: Good 76 of 365 days1994: Moderate 218 of 365 days1994: Unhealthy for Sensitive Groups 65 of 365 days1994: Unhealthy 6 of 365 days1995: Good 52 of 365 days1995: Moderate 224 of 365 days1995: Unhealthy for Sensitive Groups 72 of 365 days1995: Unhealthy 17 of 365 days19951996: Good 58 of 366 days1996: Moderate 221 of 366 days1996: Unhealthy for Sensitive Groups 71 of 366 days1996: Unhealthy 15 of 366 days1996: Very Unhealthy 1 of 366 days1997: Good 31 of 365 days1997: Moderate 231 of 365 days1997: Unhealthy for Sensitive Groups 87 of 365 days1997: Unhealthy 15 of 365 days1997: Hazardous 1 of 365 days1998: Good 34 of 365 days1998: Moderate 189 of 365 days1998: Unhealthy for Sensitive Groups 115 of 365 days1998: Unhealthy 26 of 365 days1998: Very Unhealthy 1 of 365 days1999: Good 5 of 365 days1999: Moderate 168 of 365 days1999: Unhealthy for Sensitive Groups 170 of 365 days1999: Unhealthy 22 of 365 days2000: Good 17 of 366 days2000: Moderate 182 of 366 days2000: Unhealthy for Sensitive Groups 148 of 366 days2000: Unhealthy 19 of 366 days20002001: Good 25 of 365 days2001: Moderate 256 of 365 days2001: Unhealthy for Sensitive Groups 71 of 365 days2001: Unhealthy 13 of 365 days2002: Good 28 of 365 days2002: Moderate 248 of 365 days2002: Unhealthy for Sensitive Groups 75 of 365 days2002: Unhealthy 13 of 365 days2002: Very Unhealthy 1 of 365 days2003: Good 42 of 365 days2003: Moderate 248 of 365 days2003: Unhealthy for Sensitive Groups 65 of 365 days2003: Unhealthy 10 of 365 days2004: Good 59 of 366 days2004: Moderate 256 of 366 days2004: Unhealthy for Sensitive Groups 48 of 366 days2004: Unhealthy 2 of 366 days2004: Hazardous 1 of 366 days2005: Good 47 of 365 days2005: Moderate 229 of 365 days2005: Unhealthy for Sensitive Groups 78 of 365 days2005: Unhealthy 11 of 365 days20052006: Good 26 of 365 days2006: Moderate 236 of 365 days2006: Unhealthy for Sensitive Groups 88 of 365 days2006: Unhealthy 15 of 365 days2007: Good 37 of 365 days2007: Moderate 262 of 365 days2007: Unhealthy for Sensitive Groups 64 of 365 days2007: Unhealthy 1 of 365 days2007: Hazardous 1 of 365 days2008: Good 62 of 366 days2008: Moderate 244 of 366 days2008: Unhealthy for Sensitive Groups 59 of 366 days2008: Unhealthy 1 of 366 days2009: Good 78 of 365 days2009: Moderate 264 of 365 days2009: Unhealthy for Sensitive Groups 19 of 365 days2009: Unhealthy 2 of 365 days2009: Very Unhealthy 1 of 365 days2009: Hazardous 1 of 365 days2010: Good 86 of 365 days2010: Moderate 250 of 365 days2010: Unhealthy for Sensitive Groups 27 of 365 days2010: Unhealthy 2 of 365 days20102011: Good 27 of 365 days2011: Moderate 273 of 365 days2011: Unhealthy for Sensitive Groups 48 of 365 days2011: Unhealthy 10 of 365 days2011: Very Unhealthy 4 of 365 days2011: Hazardous 3 of 365 days2012: Good 33 of 366 days2012: Moderate 265 of 366 days2012: Unhealthy for Sensitive Groups 61 of 366 days2012: Unhealthy 6 of 366 days2012: Very Unhealthy 1 of 366 days2013: Good 36 of 365 days2013: Moderate 281 of 365 days2013: Unhealthy for Sensitive Groups 41 of 365 days2013: Unhealthy 7 of 365 days2014: Good 32 of 365 days2014: Moderate 288 of 365 days2014: Unhealthy for Sensitive Groups 42 of 365 days2014: Unhealthy 2 of 365 days2014: Very Unhealthy 1 of 365 days2015: Good 62 of 365 days2015: Moderate 267 of 365 days2015: Unhealthy for Sensitive Groups 36 of 365 days20152016: Good 47 of 366 days2016: Moderate 282 of 366 days2016: Unhealthy for Sensitive Groups 36 of 366 days2016: Very Unhealthy 1 of 366 days2017: Good 38 of 365 days2017: Moderate 272 of 365 days2017: Unhealthy for Sensitive Groups 50 of 365 days2017: Unhealthy 5 of 365 days2018: Good 49 of 365 days2018: Moderate 252 of 365 days2018: Unhealthy for Sensitive Groups 57 of 365 days2018: Unhealthy 4 of 365 days2018: Very Unhealthy 3 of 365 days2019: Good 50 of 365 days2019: Moderate 277 of 365 days2019: Unhealthy for Sensitive Groups 38 of 365 days2020: Good 11 of 366 days2020: Moderate 154 of 366 days2020: Unhealthy for Sensitive Groups 60 of 366 days2020: Unhealthy 66 of 366 days2020: Very Unhealthy 75 of 366 days20202021: Good 12 of 365 days2021: Moderate 128 of 365 days2021: Unhealthy for Sensitive Groups 91 of 365 days2021: Unhealthy 61 of 365 days2021: Very Unhealthy 73 of 365 days2022: Good 27 of 365 days2022: Moderate 242 of 365 days2022: Unhealthy for Sensitive Groups 73 of 365 days2022: Unhealthy 17 of 365 days2022: Very Unhealthy 6 of 365 days2023: Good 41 of 365 days2023: Moderate 256 of 365 days2023: Unhealthy for Sensitive Groups 61 of 365 days2023: Unhealthy 7 of 365 days2024: Good 33 of 366 days2024: Moderate 260 of 366 days2024: Unhealthy for Sensitive Groups 65 of 366 days2024: Unhealthy 7 of 366 days2024: Very Unhealthy 1 of 366 days2025: Good 32 of 365 days2025: Moderate 295 of 365 days2025: Unhealthy for Sensitive Groups 32 of 365 days2025: Unhealthy 3 of 365 days2025: Very Unhealthy 1 of 365 days2025: Hazardous 2 of 365 days2025
  • Good
  • Moderate
  • Unhealthy for Sensitive Groups
  • Unhealthy
  • Very Unhealthy
  • Hazardous

Typical and high-end AQI over time

The median is the middle day of the year. The 90th percentile is the level that only the highest 10% of days exceeded.

Median and 90th-percentile daily AQI, by year0501001502002501980: 90th percentile AQI 1471981: 90th percentile AQI 1611982: 90th percentile AQI 1401983: 90th percentile AQI 1651984: 90th percentile AQI 1641985: 90th percentile AQI 1531986: 90th percentile AQI 1361987: 90th percentile AQI 1221988: 90th percentile AQI 1221989: 90th percentile AQI 1221990: 90th percentile AQI 1191991: 90th percentile AQI 1151992: 90th percentile AQI 1291993: 90th percentile AQI 1331994: 90th percentile AQI 1191995: 90th percentile AQI 1261996: 90th percentile AQI 1221997: 90th percentile AQI 1361998: 90th percentile AQI 1471999: 90th percentile AQI 1402000: 90th percentile AQI 1362001: 90th percentile AQI 1222002: 90th percentile AQI 1222003: 90th percentile AQI 1222004: 90th percentile AQI 1052005: 90th percentile AQI 1262006: 90th percentile AQI 1262007: 90th percentile AQI 1152008: 90th percentile AQI 1082009: 90th percentile AQI 932010: 90th percentile AQI 1002011: 90th percentile AQI 1192012: 90th percentile AQI 1152013: 90th percentile AQI 1052014: 90th percentile AQI 1082015: 90th percentile AQI 1002016: 90th percentile AQI 1012017: 90th percentile AQI 1082018: 90th percentile AQI 1152019: 90th percentile AQI 1012020: 90th percentile AQI 2162021: 90th percentile AQI 2132022: 90th percentile AQI 1362023: 90th percentile AQI 1192024: 90th percentile AQI 1132025: 90th percentile AQI 1011980: Median AQI 791981: Median AQI 811982: Median AQI 751983: Median AQI 761984: Median AQI 971985: Median AQI 871986: Median AQI 811987: Median AQI 771988: Median AQI 721989: Median AQI 741990: Median AQI 671991: Median AQI 671992: Median AQI 741993: Median AQI 651994: Median AQI 711995: Median AQI 741996: Median AQI 761997: Median AQI 801998: Median AQI 861999: Median AQI 1012000: Median AQI 972001: Median AQI 802002: Median AQI 802003: Median AQI 742004: Median AQI 682005: Median AQI 792006: Median AQI 842007: Median AQI 772008: Median AQI 662009: Median AQI 632010: Median AQI 642011: Median AQI 702012: Median AQI 712013: Median AQI 682014: Median AQI 692015: Median AQI 662016: Median AQI 672017: Median AQI 712018: Median AQI 712019: Median AQI 672020: Median AQI 1122021: Median AQI 1222022: Median AQI 752023: Median AQI 722024: Median AQI 772025: Median AQI 731980198519901995200020052010201520202025
  • Median daily AQI
  • 90th-percentile daily AQI

Main pollutant by day, 2025

On each monitored day, the AQI reflects whichever measured pollutant had the highest index. This counts how many days each pollutant set the AQI. A pollutant that was not measured here cannot appear.

PollutantDays as main pollutantShare of monitored days
Ozone17047%
Coarse particles (PM10)10729%
Fine particles (PM2.5)8824%

Year-by-year data

Annual AQI summary by year
YearDays with AQIGoodModerateUnhealthy for Sensitive GroupsUnhealthyVery UnhealthyHazardousMedian AQI90th pct.Max AQIMain pollutant
2025365322953231273101366Ozone
2024366332606571077113261Ozone
2023365412566170072119183Ozone
20223652724273176075136264Ozone
2021365121289161730122213297Ozone
2020366111546066750112216282Ozone
2019365502773800067101147Ozone
2018365492525743071115274Ozone
2017365382725050071108173Ozone
2016366472823601067101227Ozone
2015365622673600066100147Ozone
2014365322884221069108246Ozone
2013365362814170068105187Ozone
2012366332656161071115268Ozone
20113652727348104370119572Ozone
2010365862502720064100170Ozone
200936578264192116393317Ozone
2008366622445910066108162Ozone
2007365372626410177115408Ozone
20063652623688150084126179Ozone
20053654722978110079126177Ozone
2004366592564820168105375Ozone
20033654224865100074122195Ozone
20023652824875131080122202Ozone
20013652525671130080122185Ozone
200036617182148190097136174Ozone
199936551681702200101140185Ozone
199836534189115261086147268Ozone
19973653123187150180136362Ozone
19963665822171151076122201Ozone
19953655222472170074126185Ozone
1994365762186560071119177Ozone
199336510119351200065133200Ozone
19923668020665141074129209Ozone
1991365972105080067115177Ozone
199036510220444150067119200Ozone
1989365891987260074122198Ozone
1988366881977380072122174Ozone
1987363662177460077122166Ozone
19863654820790182081136218CO
198536542182103308087153218CO
198436635162107566097164211CO
19833658916461429076165234CO
19823659418162217075140220CO
198136563180782915081161234CO
19803639116774247079147227CO

What this data can and can’t tell you

It is a county-level summary. EPA reports one AQI per day for the county, based on the monitors operating there. Air at a particular street, school or home can differ, especially near roads, industry or wildfire smoke.

It is not a health assessment. The AQI is EPA’s scale for communicating daily air quality. A county’s history can’t tell you what the health risk is for any particular person. For daily conditions and health guidance, see AirNow.

Rules change over time. EPA has revised AQI breakpoints, most recently for fine particles in 2024, so some year-to-year change can reflect the scale rather than the air.

Counties in Arizona with a similar median AQI in 2025

All monitored counties in Arizona

Source: U.S. EPA AirData, “Annual AQI by County” files for 1980–2025 (EPA download page). EPA file dates: 2026-06-26. Imported into EnviroNearby November 5, 2026. How we use this data · Report a problem