Data / Rankings / Median Air Quality Index (US EPA) / Counties in Arizona

Counties in Arizona by median Air Quality Index (US EPA)

Pinal County had the highest median Air Quality Index (US EPA) of 13 counties in 2016, at 69. Apache County had the lowest, at 14. The median was 44. Source: the U.S. Environmental Protection Agency.

Keep it in a collection in your library.
Highest69Pinal County
Lowest14Apache County
Median4413 counties

Map of counties, 2016

Apache County: 14 indexCochise County: 44 indexCoconino County: 44 indexGila County: 44 indexLa Paz County: 42 indexMaricopa County: 67 indexMohave County: 19 indexNavajo County: 43 indexPima County: 50 indexPinal County: 69 indexSanta Cruz County: 48 indexYavapai County: 40 indexYuma County: 49 index
  • Under 41
  • 41 to 44
  • 44 to 45
  • 45 to 50
  • 50 and over
  • No data
index, 2016. Hatched areas have no value for this period. Source: EPA, EPA AirData annual AQI by county: median daily AQI. Boundaries: U.S. Census Bureau cartographic boundary files.

All counties, 2016

Pinal County: 69 indexPinal County69Maricopa County: 67 indexMaricopa County67Pima County: 50 indexPima County50Yuma County: 49 indexYuma County49Santa Cruz County: 48 indexSanta Cruz County48Cochise County: 44 indexCochise County44Coconino County: 44 indexCoconino County44Gila County: 44 indexGila County44Navajo County: 43 indexNavajo County43La Paz County: 42 indexLa Paz County42Yavapai County: 40 indexYavapai County40Mohave County: 19 indexMohave County19Apache County: 14 indexApache County14Pinal County: 69 indexPinal County69Maricopa County: 67 indexMaricopa County67Pima County: 50 indexPima County50Yuma County: 49 indexYuma County49Santa Cruz County: 48 indexSanta Cruz County48Cochise County: 44 indexCochise County44Coconino County: 44 indexCoconino County44Gila County: 44 indexGila County44Navajo County: 43 indexNavajo County43La Paz County: 42 indexLa Paz County42Yavapai County: 40 indexYavapai County40Mohave County: 19 indexMohave County19Apache County: 14 indexApache County14
index. Source: EPA, EPA AirData annual AQI by county: median daily AQI. Retrieved 2026-10-12.

Full ranking

RankCounties2016
index		Change on 2015
1Pinal County69+6
2Maricopa County67+1
3Pima County50+4
4Yuma County49+5
5Santa Cruz County48+10
6Cochise County440
6Coconino County440
6Gila County44+1
9Navajo County43+4
10La Paz County420
11Yavapai County40-1
12Mohave County19+2
13Apache County14+3

Other periods

About this ranking

Median of the daily Air Quality Index (AQI) values of a US county over the days of the year with an AQI, from the EPA AirData annual summaries.

More on how it is measured
  • The daily county AQI is the highest AQI among the monitors and pollutants reported that day (ozone, PM2.5, PM10, carbon monoxide and nitrogen dioxide).
  • Lower is cleaner: 0 to 50 is good, 51 to 100 moderate and above 100 unhealthy for sensitive groups.

United States counties with air quality monitors only, about 1,000 of some 3,100 in recent years; a county without monitors has no value. The number of days with an AQI differs between counties because some monitors run only in the ozone season.

Every value in the ranking comes from the same publisher and the same period, so the counties are compared on one definition. 2 counties with data in other periods have no value for 2016 and are left out rather than filled from another source. Equal values share a rank.

How to cite

U.S. Environmental Protection Agency, Air Quality System, AirData. EPA AirData annual AQI by county: median daily AQI. https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual. Retrieved 2026-10-12.

Citation styles

The publisher is the author. Invokely is named only as the place the figures were read, where a style asks for it.

APA 7

U.S. Environmental Protection Agency. (2026). EPA AirData annual AQI by county: median daily AQI (Counties in Arizona by median Air Quality Index (US EPA), 2016) [Data set]. Retrieved October 12, 2026, from https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual

MLA 9

EPA AirData annual AQI by county: median daily AQI, Counties in Arizona by median Air Quality Index (US EPA), 2016. U.S. Environmental Protection Agency, 13 July 2026, https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual. Invokely, https://invokely.ai/rankings/median-air-quality-index/arizona-counties?period=2016. Accessed 12 Oct. 2026.

Chicago (author-date)

U.S. Environmental Protection Agency. 2026. EPA AirData annual AQI by county: median daily AQI. Counties in Arizona by median Air Quality Index (US EPA), 2016. Dataset. Accessed October 12, 2026. https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual. Also distributed by Invokely, https://invokely.ai/rankings/median-air-quality-index/arizona-counties?period=2016.

Harvard

U.S. Environmental Protection Agency (2026) EPA AirData annual AQI by county: median daily AQI, Counties in Arizona by median Air Quality Index (US EPA), 2016 [Dataset]. Available at: https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual, via Invokely: https://invokely.ai/rankings/median-air-quality-index/arizona-counties?period=2016 (Accessed: 12 October 2026).

BibTeX
@misc{environmental_counties_in_arizona_by_2016,
  author = {{U.S. Environmental Protection Agency}},
  title = {{EPA AirData annual AQI by county: median daily AQI: Counties in Arizona by median Air Quality Index (US EPA), 2016}},
  year = {2026},
  howpublished = {Data set},
  url = {https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual},
  urldate = {2026-10-12},
  note = {Accessed via Invokely, https://invokely.ai/rankings/median-air-quality-index/arizona-counties?period=2016. Publisher attribution: U.S. Environmental Protection Agency, Air Quality System, AirData. EPA AirData annual AQI by county: median daily AQI. https://aqs.epa.gov/aqsweb/airdata/download\_files.html\#Annual. Retrieved 2026-10-12.},
}
RIS
TY  - DATA
AU  - U.S. Environmental Protection Agency
TI  - EPA AirData annual AQI by county: median daily AQI: Counties in Arizona by median Air Quality Index (US EPA), 2016
PY  - 2026
DA  - 2026/07/13
PB  - U.S. Environmental Protection Agency
DB  - Invokely
UR  - https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual
L2  - https://invokely.ai/rankings/median-air-quality-index/arizona-counties?period=2016
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/median-air-quality-index/arizona-counties?period=2016.
N1  - Publisher attribution: U.S. Environmental Protection Agency, Air Quality System, AirData. EPA AirData annual AQI by county: median daily AQI. https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual. Retrieved 2026-10-12.
ER  -
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Rank Counties in Arizona by median Air Quality Index (US EPA) using official data, and cite the source.
rank_places {"indicator":"aqi_median","level":"province","within":"Arizona","limit":10}
GET https://invokely.ai/api/v1/rank?indicator=aqi_median&level=province&within=Arizona&limit=10

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Questions

Which county has the highest median Air Quality Index (US EPA)?

Pinal County, with 69 in 2016, according to the U.S. Environmental Protection Agency.

Which county has the lowest median Air Quality Index (US EPA)?

Apache County, with 14 in 2016.

Where does this ranking come from?

Every value comes from one source and one period, so the places are comparable: U.S. Environmental Protection Agency, EPA AirData annual AQI by county: median daily AQI. Retrieved 2026-10-12. 2 counties have no value for 2016 and are not ranked.

Median Air Quality Index (US EPA): other rankings

Counties in Arizona: more rankings