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 2020, at 192. Karnes County had the lowest, at 32. The median was 125. Source: the U.S. Environmental Protection Agency.

Highest192El Paso County

Lowest32Karnes County

Median12545 counties

Map of counties, 2020

Under 86
86 to 100
100 to 130
130 to 140
140 to 160
160 and over
No data

index, 2020. 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, 2020

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

Full ranking

Rank	Counties	2020 index	Change on 2019
1	El Paso County	192	+33
2	Harris County	190	-12
3	Cameron County	184	+93
4	Brazoria County	182	+21
5	Kleberg County	174	+85
6	Maverick County	164	+60
7	Webb County	163	+54
8	Nueces County	162	+55
9	Bexar County	160	-15
10	Tarrant County	159	+12
11	Atascosa County	158	n/a
12	Hidalgo County	157	+51
13	Collin County	154	-2
13	Travis County	154	+39
15	Galveston County	143	+7
16	Denton County	142	+9
17	Bell County	135	+30
17	Dallas County	135	-8
19	Kaufman County	134	+41
20	Rockwall County	133	+28
21	Montgomery County	129	-14
22	Bowie County	127	+18
23	Ellis County	125	+28
24	Jefferson County	122	-28
25	Parker County	115	+15
26	Navarro County	113	+13
27	Culberson County	112	+4
28	Johnson County	105	-38
29	Orange County	103	+3
30	Harrison County	100	+10
30	Hood County	100	-33
30	Victoria County	100	+13
33	Brazos County	99	n/a
34	McLennan County	97	+10
35	Ector County	96	+14
36	Randall County	90	-22
37	Hunt County	87	-10
38	Potter County	85	+20
39	Smith County	84	-49
40	Lubbock County	83	-20
41	Brewster County	80	-13
42	Gregg County	74	-38
43	Polk County	71	-3
44	Wilson County	34	n/a
45	Karnes County	32	n/a

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 2020 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), 2020) [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), 2020. 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=2020. 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), 2020. 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=2020.

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), 2020 [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=2020 (Accessed: 12 October 2026).

BibTeX

@misc{environmental_counties_in_texas_by_2020,
  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), 2020}},
  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=2020. 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), 2020
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=2020
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/highest-daily-air-quality-index/texas-counties?period=2020.
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  -

Embed this chart

Paste this code into a web page or a blog post. The chart shows the latest figures as they are published, with the source and a link back to this page.

Embed code

<iframe src="https://invokely.ai/embed/rankings/highest-daily-air-quality-index/texas-counties?period=2020" width="760" height="500" title="Counties in Texas by highest daily Air Quality Index (US EPA), 2020, chart from Invokely" loading="lazy" style="border:0;width:100%;max-width:760px" referrerpolicy="strict-origin-when-cross-origin"></iframe>

Sites that read oEmbed links, such as WordPress, can show the chart when you paste the link to this page.

Use this data in your AI agent

Invokely serves this figure to AI assistants through MCP and to code through a REST API, with the source and citation attached. Ask your assistant:

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}
GET https://invokely.ai/api/v1/rank?indicator=aqi_max&level=province&within=Texas&limit=10

Connect Claude, ChatGPT or Cursor in one step. The trial answers 25 calls a day without an account.

Questions

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

El Paso County, with 192 in 2020, 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 2020.

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 2020 and are not ranked.