Counties in Texas by highest daily Air Quality Index (US EPA)

El Paso County had the highest highest daily Air Quality Index (US EPA) of 45 counties in 2024, at 431. Karnes County had the lowest, at 33. The median was 129. Source: the U.S. Environmental Protection Agency.

Highest431El Paso County

Lowest33Karnes County

Median12945 counties

Map of counties, 2024

Under 100
100 to 120
120 to 130
130 to 150
150 to 170
170 and over
No data

index, 2024. Hatched areas have no value for this period. Source: EPA, EPA AirData annual AQI by county: highest daily AQI. Boundaries: U.S. Census Bureau cartographic boundary files.

All counties, 2024

index. Source: EPA, EPA AirData annual AQI by county: highest daily AQI. Retrieved 2026-10-12.

Full ranking

Rank	Counties	2024 index	Change on 2023
1	El Paso County	431	+276
2	Harrison County	263	+152
3	Tarrant County	203	+31
4	Harris County	201	-4
5	Bexar County	199	-110
6	Denton County	187	+10
7	Dallas County	185	+13
8	Cameron County	171	+30
9	Montgomery County	166	+44
10	Brazoria County	164	+8
11	Collin County	161	+7
12	Galveston County	159	0
13	Hidalgo County	157	+62
14	Parker County	156	+16
15	Hood County	154	+11
16	Nueces County	153	+52
17	Kaufman County	147	-12
18	Jefferson County	143	-11
19	Travis County	141	+19
20	Potter County	138	+13
21	Hunt County	133	+14
21	McLennan County	133	+4
23	Bell County	129	-4
23	Gregg County	129	-22
23	Johnson County	129	+3
23	Navarro County	129	+29
23	Webb County	129	-4
28	Rockwall County	126	+26
29	Kleberg County	121	+32
30	Orange County	119	+18
31	Atascosa County	116	+30
32	Brewster County	112	+11
33	Randall County	108	-4
34	Smith County	105	-14
34	Victoria County	105	+31
36	Brazos County	102	+23
37	Ellis County	101	-11
38	Maverick County	100	-1
39	Bowie County	97	-10
40	Polk County	93	-7
41	Lubbock County	91	-70
42	Culberson County	88	-1
42	Ector County	88	+4
44	Wilson County	34	-2
45	Karnes County	33	+4

Other periods

About this ranking

Highest daily Air Quality Index (AQI) value recorded in a US county during the year, from the EPA AirData annual summaries. Values above 500 are beyond the AQI scale and are published as EPA computes them.

A single day decides the value, so one wildfire or dust event can set it. Dust from the dry Owens Lake bed puts Inyo and Mono counties in California in the thousands. 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 2024 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: highest 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: highest daily AQI (Counties in Texas by highest daily Air Quality Index (US EPA), 2024) [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: highest daily AQI, Counties in Texas by highest daily Air Quality Index (US EPA), 2024. U.S. Environmental Protection Agency, 13 July 2026, https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual. Invokely, https://invokely.ai/rankings/highest-daily-air-quality-index/texas-counties?period=2024. Accessed 12 Oct. 2026.

Chicago (author-date)

U.S. Environmental Protection Agency. 2026. EPA AirData annual AQI by county: highest daily AQI. Counties in Texas by highest daily Air Quality Index (US EPA), 2024. Dataset. Accessed October 12, 2026. https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual. Also distributed by Invokely, https://invokely.ai/rankings/highest-daily-air-quality-index/texas-counties?period=2024.

Harvard

U.S. Environmental Protection Agency (2026) EPA AirData annual AQI by county: highest daily AQI, Counties in Texas by highest daily Air Quality Index (US EPA), 2024 [Dataset]. Available at: https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual, via Invokely: https://invokely.ai/rankings/highest-daily-air-quality-index/texas-counties?period=2024 (Accessed: 12 October 2026).

BibTeX

@misc{environmental_counties_in_texas_by_2024,
  author = {{U.S. Environmental Protection Agency}},
  title = {{EPA AirData annual AQI by county: highest daily AQI: Counties in Texas by highest daily Air Quality Index (US EPA), 2024}},
  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/highest-daily-air-quality-index/texas-counties?period=2024. Publisher attribution: U.S. Environmental Protection Agency, Air Quality System, AirData. EPA AirData annual AQI by county: highest 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: highest daily AQI: Counties in Texas by highest daily Air Quality Index (US EPA), 2024
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/highest-daily-air-quality-index/texas-counties?period=2024
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/highest-daily-air-quality-index/texas-counties?period=2024.
N1  - Publisher attribution: U.S. Environmental Protection Agency, Air Quality System, AirData. EPA AirData annual AQI by county: highest 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 highest daily Air Quality Index (US EPA) using official data, and cite the source.

rank_places {"indicator":"aqi_max","level":"province","within":"Texas","limit":10}
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Questions

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

El Paso County, with 431 in 2024, according to the U.S. Environmental Protection Agency.

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

Karnes County, with 33 in 2024.

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: highest daily AQI. Retrieved 2026-10-12. 18 counties have no value for 2024 and are not ranked.