Data / Rankings / Share of days with good air quality (US EPA AQI) / Counties in Texas

Counties in Texas by share of days with good air quality (US EPA AQI)

Karnes County had the highest share of days with good air quality (US EPA AQI) of 45 counties in 2021, at 100%. Harris County had the lowest, at 17.5%. The median was 72.2%. Source: EPA.

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Highest100Karnes County
Lowest17.5Harris County
Median72.245 counties

Map of counties, 2021

Atascosa County: 59.8 %Bell County: 65.8 %Bexar County: 31 %Bowie County: 45.7 %Brazoria County: 90.7 %Brazos County: 69.7 %Brewster County: 80.6 %Cameron County: 44.4 %Collin County: 82.4 %Culberson County: 76.9 %Dallas County: 57.5 %Denton County: 60.8 %Ector County: 77.1 %Ellis County: 72.2 %El Paso County: 24.9 %Galveston County: 71.7 %Gregg County: 92.1 %Harris County: 17.5 %Harrison County: 56.6 %Hidalgo County: 46.6 %Hood County: 92.7 %Hunt County: 94.8 %Jefferson County: 63.3 %Johnson County: 85.7 %Karnes County: 100 %Kaufman County: 73.7 %Kleberg County: 53.2 %Lubbock County: 80.1 %McLennan County: 76.9 %Maverick County: 67.7 %Montgomery County: 56.8 %Navarro County: 72.9 %Nueces County: 54.9 %Orange County: 72 %Parker County: 88.1 %Polk County: 98.9 %Potter County: 82.8 %Randall County: 81.4 %Rockwall County: 95.3 %Smith County: 92.2 %Tarrant County: 44.1 %Travis County: 49.9 %Victoria County: 95.3 %Webb County: 54 %Wilson County: 100 %
  • Under 51
  • 51 to 60
  • 60 to 72
  • 72 to 81
  • 81 to 92
  • 92 and over
  • No data
%, 2021. Hatched areas have no value for this period. Source: Invokely calculation with data from EPA. Boundaries: U.S. Census Bureau cartographic boundary files.

All counties, 2021

Karnes County: 100 %Karnes County100Wilson County: 100 %Wilson County100Polk County: 98.9 %Polk County98.9Rockwall County: 95.3 %Rockwall County95.3Victoria County: 95.3 %Victoria County95.3Hunt County: 94.8 %Hunt County94.8Hood County: 92.7 %Hood County92.7Smith County: 92.2 %Smith County92.2Gregg County: 92.1 %Gregg County92.1Brazoria County: 90.7 %Brazoria County90.7Parker County: 88.1 %Parker County88.1Johnson County: 85.7 %Johnson County85.7Potter County: 82.8 %Potter County82.8Collin County: 82.4 %Collin County82.4Randall County: 81.4 %Randall County81.4Brewster County: 80.6 %Brewster County80.6Lubbock County: 80.1 %Lubbock County80.1Ector County: 77.1 %Ector County77.1Culberson County: 76.9 %Culberson County76.9McLennan County: 76.9 %McLennan County76.9Kaufman County: 73.7 %Kaufman County73.7Navarro County: 72.9 %Navarro County72.9Ellis County: 72.2 %Ellis County72.2Orange County: 72 %Orange County72Galveston County: 71.7 %Galveston County71.7Brazos County: 69.7 %Brazos County69.7Maverick County: 67.7 %Maverick County67.7Bell County: 65.8 %Bell County65.8Jefferson County: 63.3 %Jefferson County63.3Denton County: 60.8 %Denton County60.8Atascosa County: 59.8 %Atascosa County59.8Dallas County: 57.5 %Dallas County57.5Montgomery County: 56.8 %Montgomery County56.8Harrison County: 56.6 %Harrison County56.6Nueces County: 54.9 %Nueces County54.9Webb County: 54 %Webb County54Kleberg County: 53.2 %Kleberg County53.2Travis County: 49.9 %Travis County49.9Hidalgo County: 46.6 %Hidalgo County46.6Bowie County: 45.7 %Bowie County45.7Cameron County: 44.4 %Cameron County44.4Tarrant County: 44.1 %Tarrant County44.1Bexar County: 31 %Bexar County31El Paso County: 24.9 %El Paso County24.9Harris County: 17.5 %Harris County17.5Karnes County: 100 %Karnes County100Wilson County: 100 %Wilson County100Polk County: 98.9 %Polk County98.9Rockwall County: 95.3 %Rockwall County95.3Victoria County: 95.3 %Victoria County95.3Hunt County: 94.8 %Hunt County94.8Hood County: 92.7 %Hood County92.7Smith County: 92.2 %Smith County92.2Gregg County: 92.1 %Gregg County92.1Brazoria County: 90.7 %Brazoria County90.7Parker County: 88.1 %Parker County88.1Johnson County: 85.7 %Johnson County85.7Potter County: 82.8 %Potter County82.8Collin County: 82.4 %Collin County82.4Randall County: 81.4 %Randall County81.4Brewster County: 80.6 %Brewster County80.6Lubbock County: 80.1 %Lubbock County80.1Ector County: 77.1 %Ector County77.1Culberson County: 76.9 %Culberson County76.9McLennan County: 76.9 %McLennan County76.9Kaufman County: 73.7 %Kaufman County73.7Navarro County: 72.9 %Navarro County72.9Ellis County: 72.2 %Ellis County72.2Orange County: 72 %Orange County72Galveston County: 71.7 %Galveston County71.7Brazos County: 69.7 %Brazos County69.7Maverick County: 67.7 %Maverick County67.7Bell County: 65.8 %Bell County65.8Jefferson County: 63.3 %Jefferson County63.3Denton County: 60.8 %Denton County60.8Atascosa County: 59.8 %Atascosa County59.8Dallas County: 57.5 %Dallas County57.5Montgomery County: 56.8 %Montgomery County56.8Harrison County: 56.6 %Harrison County56.6Nueces County: 54.9 %Nueces County54.9Webb County: 54 %Webb County54Kleberg County: 53.2 %Kleberg County53.2Travis County: 49.9 %Travis County49.9Hidalgo County: 46.6 %Hidalgo County46.6Bowie County: 45.7 %Bowie County45.7Cameron County: 44.4 %Cameron County44.4Tarrant County: 44.1 %Tarrant County44.1Bexar County: 31 %Bexar County31El Paso County: 24.9 %El Paso County24.9Harris County: 17.5 %Harris County17.5
%. Source: Invokely calculation with data from EPA. Retrieved 2026-10-12.

Full ranking

RankCounties2021 (%)Change on 2020
1Karnes County1000 pts
1Wilson County1000 pts
3Polk County98.9+1.4 pts
4Rockwall County95.3+0.3 pts
4Victoria County95.3+1.7 pts
6Hunt County94.8-1.1 pts
7Hood County92.7+0.3 pts
8Smith County92.2-4 pts
9Gregg County92.1-6.2 pts
10Brazoria County90.7+0.8 pts
11Parker County88.1-3.3 pts
12Johnson County85.7-6 pts
13Potter County82.8-7.2 pts
14Collin County82.4-4.4 pts
15Randall County81.4+3.8 pts
16Brewster County80.6-6.6 pts
17Lubbock County80.1-8.3 pts
18Ector County77.1-1.2 pts
19Culberson County76.9+14.7 pts
19McLennan County76.9-3.4 pts
21Kaufman County73.7+2.7 pts
22Navarro County72.9+2.7 pts
23Ellis County72.2+6.9 pts
24Orange County72+10.4 pts
25Galveston County71.7+5.6 pts
26Brazos County69.7+0.4 pts
27Maverick County67.7-5.5 pts
28Bell County65.8+1.3 pts
29Jefferson County63.3+3 pts
30Denton County60.8-6.1 pts
31Atascosa County59.8-9.8 pts
32Dallas County57.5-2.1 pts
33Montgomery County56.8-3 pts
34Harrison County56.6-16.1 pts
35Nueces County54.9-7.1 pts
36Webb County54-5.3 pts
37Kleberg County53.2-1.6 pts
38Travis County49.9+0.2 pts
39Hidalgo County46.6-14.1 pts
40Bowie County45.7-8.2 pts
41Cameron County44.4+1.2 pts
42Tarrant County44.1-0.4 pts
43Bexar County31-1.5 pts
44El Paso County24.9-1.1 pts
45Harris County17.5-12.3 pts

Other periods

About this ranking

Days with a daily Air Quality Index of 0 to 50 (good) as a percentage of the days of the year with an AQI in a US county. Calculated by Invokely from the day counts in the EPA AirData annual summaries; both counts are stored with each value.

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: good days as a share of days with an AQI, calculated with stored counts. 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: good days as a share of days with an AQI, calculated with stored counts (Counties in Texas by share of days with good air quality (US EPA AQI), 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: good days as a share of days with an AQI, calculated with stored counts, Counties in Texas by share of days with good air quality (US EPA AQI), 2021. U.S. Environmental Protection Agency, 13 July 2026, https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual. Invokely, https://invokely.ai/rankings/good-air-quality-days-share/texas-counties?period=2021. Accessed 12 Oct. 2026.

Chicago (author-date)

U.S. Environmental Protection Agency. 2026. EPA AirData annual AQI by county: good days as a share of days with an AQI, calculated with stored counts. Counties in Texas by share of days with good air quality (US EPA AQI), 2021. Dataset. Accessed October 12, 2026. https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual. Also distributed by Invokely, https://invokely.ai/rankings/good-air-quality-days-share/texas-counties?period=2021.

Harvard

U.S. Environmental Protection Agency (2026) EPA AirData annual AQI by county: good days as a share of days with an AQI, calculated with stored counts, Counties in Texas by share of days with good air quality (US EPA AQI), 2021 [Dataset]. Available at: https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual, via Invokely: https://invokely.ai/rankings/good-air-quality-days-share/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: good days as a share of days with an AQI, calculated with stored counts: Counties in Texas by share of days with good air quality (US EPA AQI), 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/good-air-quality-days-share/texas-counties?period=2021. Publisher attribution: U.S. Environmental Protection Agency, Air Quality System, AirData. EPA AirData annual AQI by county: good days as a share of days with an AQI, calculated with stored counts. 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: good days as a share of days with an AQI, calculated with stored counts: Counties in Texas by share of days with good air quality (US EPA AQI), 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/good-air-quality-days-share/texas-counties?period=2021
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/good-air-quality-days-share/texas-counties?period=2021.
N1  - Publisher attribution: U.S. Environmental Protection Agency, Air Quality System, AirData. EPA AirData annual AQI by county: good days as a share of days with an AQI, calculated with stored counts. https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual. Retrieved 2026-10-12.
ER  -
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Rank Counties in Texas by share of days with good air quality (US EPA AQI) using official data, and cite the source.
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Questions

Which county has the highest share of days with good air quality (US EPA AQI)?

Karnes County, with 100% in 2021, according to EPA.

Which county has the lowest share of days with good air quality (US EPA AQI)?

Harris County, with 17.5% 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: good days as a share of days with an AQI, calculated with stored counts. Retrieved 2026-10-12. 18 counties have no value for 2021 and are not ranked.

Share of days with good air quality (US EPA AQI): other rankings

Counties in Texas: more rankings