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

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

El Paso County had the highest median Air Quality Index (US EPA) of 45 counties in 2021, at 59. Karnes County had the lowest, at 6. The median was 42. Source: the U.S. Environmental Protection Agency.

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Highest59El Paso County
Lowest6Karnes County
Median4245 counties

Map of counties, 2021

Atascosa County: 43 indexBell County: 44 indexBexar County: 55 indexBowie County: 52 indexBrazoria County: 34 indexBrazos County: 40 indexBrewster County: 42 indexCameron County: 52 indexCollin County: 37 indexCulberson County: 43 indexDallas County: 47 indexDenton County: 45 indexEctor County: 35 indexEllis County: 43 indexEl Paso County: 59 indexGalveston County: 43 indexGregg County: 33 indexHarris County: 58 indexHarrison County: 47 indexHidalgo County: 52 indexHood County: 35 indexHunt County: 33 indexJefferson County: 44 indexJohnson County: 37 indexKarnes County: 6 indexKaufman County: 40 indexKleberg County: 48 indexLubbock County: 31 indexMcLennan County: 39 indexMaverick County: 37 indexMontgomery County: 47 indexNavarro County: 41 indexNueces County: 47 indexOrange County: 41 indexParker County: 36 indexPolk County: 30 indexPotter County: 31 indexRandall County: 42 indexRockwall County: 31 indexSmith County: 35 indexTarrant County: 52 indexTravis County: 51 indexVictoria County: 32 indexWebb County: 48 indexWilson County: 7 index
  • Under 33
  • 33 to 37
  • 37 to 42
  • 42 to 44
  • 44 to 50
  • 50 and over
  • No data
index, 2021. 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, 2021

El Paso County: 59 indexEl Paso County59Harris County: 58 indexHarris County58Bexar County: 55 indexBexar County55Bowie County: 52 indexBowie County52Cameron County: 52 indexCameron County52Hidalgo County: 52 indexHidalgo County52Tarrant County: 52 indexTarrant County52Travis County: 51 indexTravis County51Kleberg County: 48 indexKleberg County48Webb County: 48 indexWebb County48Dallas County: 47 indexDallas County47Harrison County: 47 indexHarrison County47Montgomery County: 47 indexMontgomery County47Nueces County: 47 indexNueces County47Denton County: 45 indexDenton County45Bell County: 44 indexBell County44Jefferson County: 44 indexJefferson County44Atascosa County: 43 indexAtascosa County43Culberson County: 43 indexCulberson County43Ellis County: 43 indexEllis County43Galveston County: 43 indexGalveston County43Brewster County: 42 indexBrewster County42Randall County: 42 indexRandall County42Navarro County: 41 indexNavarro County41Orange County: 41 indexOrange County41Brazos County: 40 indexBrazos County40Kaufman County: 40 indexKaufman County40McLennan County: 39 indexMcLennan County39Collin County: 37 indexCollin County37Johnson County: 37 indexJohnson County37Maverick County: 37 indexMaverick County37Parker County: 36 indexParker County36Ector County: 35 indexEctor County35Hood County: 35 indexHood County35Smith County: 35 indexSmith County35Brazoria County: 34 indexBrazoria County34Gregg County: 33 indexGregg County33Hunt County: 33 indexHunt County33Victoria County: 32 indexVictoria County32Lubbock County: 31 indexLubbock County31Potter County: 31 indexPotter County31Rockwall County: 31 indexRockwall County31Polk County: 30 indexPolk County30Wilson County: 7 indexWilson County7Karnes County: 6 indexKarnes County6El Paso County: 59 indexEl Paso County59Harris County: 58 indexHarris County58Bexar County: 55 indexBexar County55Bowie County: 52 indexBowie County52Cameron County: 52 indexCameron County52Hidalgo County: 52 indexHidalgo County52Tarrant County: 52 indexTarrant County52Travis County: 51 indexTravis County51Kleberg County: 48 indexKleberg County48Webb County: 48 indexWebb County48Dallas County: 47 indexDallas County47Harrison County: 47 indexHarrison County47Montgomery County: 47 indexMontgomery County47Nueces County: 47 indexNueces County47Denton County: 45 indexDenton County45Bell County: 44 indexBell County44Jefferson County: 44 indexJefferson County44Atascosa County: 43 indexAtascosa County43Culberson County: 43 indexCulberson County43Ellis County: 43 indexEllis County43Galveston County: 43 indexGalveston County43Brewster County: 42 indexBrewster County42Randall County: 42 indexRandall County42Navarro County: 41 indexNavarro County41Orange County: 41 indexOrange County41Brazos County: 40 indexBrazos County40Kaufman County: 40 indexKaufman County40McLennan County: 39 indexMcLennan County39Collin County: 37 indexCollin County37Johnson County: 37 indexJohnson County37Maverick County: 37 indexMaverick County37Parker County: 36 indexParker County36Ector County: 35 indexEctor County35Hood County: 35 indexHood County35Smith County: 35 indexSmith County35Brazoria County: 34 indexBrazoria County34Gregg County: 33 indexGregg County33Hunt County: 33 indexHunt County33Victoria County: 32 indexVictoria County32Lubbock County: 31 indexLubbock County31Potter County: 31 indexPotter County31Rockwall County: 31 indexRockwall County31Polk County: 30 indexPolk County30Wilson County: 7 indexWilson County7Karnes County: 6 indexKarnes County6
index. Source: EPA, EPA AirData annual AQI by county: median daily AQI. Retrieved 2026-10-12.

Full ranking

RankCounties2021
index		Change on 2020
1El Paso County590
2Harris County58+2
3Bexar County550
4Bowie County52+4
4Cameron County520
4Hidalgo County52+8
4Tarrant County520
8Travis County510
9Kleberg County48+2
9Webb County48+1
11Dallas County47+1
11Harrison County47+7
11Montgomery County47+3
11Nueces County47+1
15Denton County45+1
16Bell County440
16Jefferson County44-2
18Atascosa County43+5
18Culberson County43-3
18Ellis County43-2
18Galveston County43-1
22Brewster County42+1
22Randall County420
24Navarro County41-1
24Orange County41-3
26Brazos County400
26Kaufman County40-2
28McLennan County390
29Collin County370
29Johnson County37+3
29Maverick County37+1
32Parker County36+1
33Ector County35-1
33Hood County35+2
33Smith County35+2
36Brazoria County34+1
37Gregg County33+2
37Hunt County33+1
39Victoria County32+1
40Lubbock County31+5
40Potter County31+5
40Rockwall County31-1
43Polk County30-1
44Wilson County70
45Karnes County60

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. 18 counties with data in other periods have no value for 2021 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 Texas by median Air Quality Index (US EPA), 2021) [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 Texas by median Air Quality Index (US EPA), 2021. 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/texas-counties?period=2021. Accessed 12 Oct. 2026.

Chicago (author-date)

U.S. Environmental Protection Agency. 2026. EPA AirData annual AQI by county: median daily AQI. Counties in Texas by median Air Quality Index (US EPA), 2021. 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/texas-counties?period=2021.

Harvard

U.S. Environmental Protection Agency (2026) EPA AirData annual AQI by county: median daily AQI, Counties in Texas by median Air Quality Index (US EPA), 2021 [Dataset]. Available at: https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual, via Invokely: https://invokely.ai/rankings/median-air-quality-index/texas-counties?period=2021 (Accessed: 12 October 2026).

BibTeX
@misc{environmental_counties_in_texas_by_2021,
  author = {{U.S. Environmental Protection Agency}},
  title = {{EPA AirData annual AQI by county: median daily AQI: Counties in Texas by median Air Quality Index (US EPA), 2021}},
  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/texas-counties?period=2021. 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 Texas by median Air Quality Index (US EPA), 2021
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/texas-counties?period=2021
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/median-air-quality-index/texas-counties?period=2021.
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 Texas by median Air Quality Index (US EPA) using official data, and cite the source.
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Questions

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

El Paso County, with 59 in 2021, according to the U.S. Environmental Protection Agency.

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

Karnes County, with 6 in 2021.

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. 18 counties have no value for 2021 and are not ranked.

Median Air Quality Index (US EPA): other rankings

Counties in Texas: more rankings