Counties in Texas by highest daily Air Quality Index (US EPA), 2025

El Paso County had the highest highest daily Air Quality Index (US EPA) of 45 counties in 2025, at 2,122. Karnes County had the lowest, at 32. The median was 126. Source: the U.S. Environmental Protection Agency.

Highest2,122El Paso County

Lowest32Karnes County

Median12645 counties

Map of counties, 2025

Under 90
90 to 110
110 to 130
130 to 140
140 to 160
160 and over
No data

index, 2025. 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, 2025

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

Full ranking

Rank	Counties	2025 index	Change on 2024
1	El Paso County	2,122	+1,691
2	Dallas County	304	+119
3	Ector County	183	+95
4	Denton County	179	-8
4	Galveston County	179	+20
6	Harris County	172	-29
7	Lubbock County	167	+76
8	Brewster County	164	+52
9	Tarrant County	162	-41
10	Jefferson County	160	+17
11	Culberson County	159	+71
12	Collin County	156	-5
13	Bexar County	154	-45
14	Parker County	147	-9
15	Brazoria County	143	-21
16	McLennan County	142	+9
17	Bell County	140	+11
17	Hidalgo County	140	-17
19	Cameron County	139	-32
20	Nueces County	137	-16
21	Montgomery County	133	-33
22	Travis County	129	-12
23	Kaufman County	126	-21
24	Hood County	122	-32
25	Webb County	121	-8
26	Hunt County	119	-14
27	Gregg County	115	-14
28	Rockwall County	108	-18
29	Bowie County	107	+10
29	Kleberg County	107	-14
29	Navarro County	107	-22
32	Polk County	105	+12
33	Johnson County	101	-28
34	Harrison County	100	-163
34	Victoria County	100	-5
36	Randall County	97	-11
37	Ellis County	93	-8
37	Smith County	93	-12
39	Atascosa County	92	-24
40	Maverick County	90	-10
40	Orange County	90	-29
42	Potter County	85	-53
43	Brazos County	78	-24
44	Wilson County	41	+7
45	Karnes County	32	-1

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 2025 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), 2025) [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), 2025. 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. 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), 2025. 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.

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), 2025 [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 (Accessed: 12 October 2026).

BibTeX

@misc{environmental_counties_in_texas_by_2025,
  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), 2025}},
  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. 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), 2025
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
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/highest-daily-air-quality-index/texas-counties.
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.

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Questions

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

El Paso County, with 2,122 in 2025, according to the U.S. Environmental Protection Agency.

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

Karnes County, with 32 in 2025.

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 2025 and are not ranked.