Data / Median Air Quality Index (US EPA) / Jefferson County

Median Air Quality Index (US EPA) in Jefferson County

Median Air Quality Index (US EPA) in Jefferson County was 51 in 2025, according to the U.S. Environmental Protection Agency. That is down 2 from 2024. That is the 11th highest of 45 counties in 2025.

2025, index51
Change on 2024-2
Rank11th of 45Counties in Texas ranked
Series high602005
Series low281981

Next release: Tuesday, 13 July 2027, estimated by Invokely from past publication dates (low confidence), not announced by the publisher. Release calendar

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Median Air Quality Index (US EPA) in Jefferson County, 1980 to 2025

203040506019801987199420012008201520251980: 35 index1981: 28 index1982: 38 index1983: 38 index1984: 37 index1985: 28 index1986: 35 index1987: 38 index1988: 40 index1989: 32 index1990: 34 index1991: 37 index1992: 41 index1993: 40 index1994: 36 index1995: 38 index1996: 32 index1997: 35 index1998: 33 index1999: 32 index2000: 51 index2001: 54 index2002: 52 index2003: 55 index2004: 54 index2005: 60 index2006: 58 index2007: 57 index2008: 55 index2009: 52 index2010: 54 index2011: 53 index2012: 52 index2013: 52 index2014: 51 index2015: 47 index2016: 45 index2017: 47 index2018: 53 index2019: 49 index2020: 46 index2021: 44 index2022: 48 index2023: 54 index2024: 53 index2025: 51 index203040506019801996201220251980: 35 index1981: 28 index1982: 38 index1983: 38 index1984: 37 index1985: 28 index1986: 35 index1987: 38 index1988: 40 index1989: 32 index1990: 34 index1991: 37 index1992: 41 index1993: 40 index1994: 36 index1995: 38 index1996: 32 index1997: 35 index1998: 33 index1999: 32 index2000: 51 index2001: 54 index2002: 52 index2003: 55 index2004: 54 index2005: 60 index2006: 58 index2007: 57 index2008: 55 index2009: 52 index2010: 54 index2011: 53 index2012: 52 index2013: 52 index2014: 51 index2015: 47 index2016: 45 index2017: 47 index2018: 53 index2019: 49 index2020: 46 index2021: 44 index2022: 48 index2023: 54 index2024: 53 index2025: 51 index
index. Source: EPA, EPA AirData annual AQI by county: median daily AQI. Retrieved 2026-10-12, published 2026-07-13.
All 46 values
Periodindex
202551
202453
202354
202248
202144
202046
201949
201853
201747
201645
201547
201451
201352
201252
201153
201054
200952
200855
200757
200658
200560
200454
200355
200252
200154
200051
199932
199833
199735
199632
199538
199436
199340
199241
199137
199034
198932
198840
198738
198635
198528
198437
198338
198238
198128
198035

Jefferson County compared with nearby places

Atascosa County: 35 indexBell County: 45 indexBexar County: 52 indexBowie County: 48 indexBrazoria County: 35 indexBrazos County: 40 indexBrewster County: 43 indexCameron County: 57 indexCollin County: 40 indexCulberson County: 32 indexDallas County: 53 indexDenton County: 47 indexEctor County: 39 indexEllis County: 35 indexEl Paso County: 70 indexGalveston County: 45 indexGregg County: 36 indexHarris County: 62 indexHarrison County: 44 indexHidalgo County: 52 indexHood County: 38 indexHunt County: 34 indexJefferson County: 51 indexJohnson County: 37 indexKarnes County: 6 indexKaufman County: 44 indexKleberg County: 49 indexLubbock County: 24 indexMcLennan County: 51 indexMaverick County: 42 indexMontgomery County: 53 indexNavarro County: 47 indexNueces County: 53 indexOrange County: 45 indexParker County: 38 indexPolk County: 33 indexPotter County: 16 indexRandall County: 41 indexRockwall County: 31 indexSmith County: 35 indexTarrant County: 56 indexTravis County: 53 indexVictoria County: 34 indexWebb County: 51 indexWilson County: 8 index
  • Under 34
  • 34 to 38
  • 38 to 43
  • 43 to 47
  • 47 to 53
  • 53 and over
  • No data
Median Air Quality Index (US EPA), 2025, index. Jefferson County is outlined. Same source and period for every area shown. Source: U.S. Environmental Protection Agency. Boundaries: U.S. Census Bureau cartographic boundary files.

Rankings

Definition

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.

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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 (Median Air Quality Index (US EPA), Jefferson County, 1980 to 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: median daily AQI, Median Air Quality Index (US EPA), Jefferson County, 1980 to 2025. U.S. Environmental Protection Agency, 13 July 2026, https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual. Invokely, https://invokely.ai/en/median-air-quality-index/jefferson-county-texas. Accessed 12 Oct. 2026.

Chicago (author-date)

U.S. Environmental Protection Agency. 2026. EPA AirData annual AQI by county: median daily AQI. Median Air Quality Index (US EPA), Jefferson County, 1980 to 2025. Dataset. Accessed October 12, 2026. https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual. Also distributed by Invokely, https://invokely.ai/en/median-air-quality-index/jefferson-county-texas.

Harvard

U.S. Environmental Protection Agency (2026) EPA AirData annual AQI by county: median daily AQI, Median Air Quality Index (US EPA), Jefferson County, 1980 to 2025 [Dataset]. Available at: https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual, via Invokely: https://invokely.ai/en/median-air-quality-index/jefferson-county-texas (Accessed: 12 October 2026).

BibTeX
@misc{environmental_median_air_quality_index_2025,
  author = {{U.S. Environmental Protection Agency}},
  title = {{EPA AirData annual AQI by county: median daily AQI: Median Air Quality Index (US EPA), Jefferson County, 1980 to 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/en/median-air-quality-index/jefferson-county-texas. 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: Median Air Quality Index (US EPA), Jefferson County, 1980 to 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/en/median-air-quality-index/jefferson-county-texas
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/en/median-air-quality-index/jefferson-county-texas.
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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Questions

What is the median Air Quality Index (US EPA) in Jefferson County?

Median Air Quality Index (US EPA) in Jefferson County was 51 in 2025, according to the U.S. Environmental Protection Agency. That is down 2 from 2024. That is the 11th highest of 45 counties in 2025.

Where does this figure come from?

U.S. Environmental Protection Agency. EPA AirData annual AQI by county: median daily AQI. Retrieved by Invokely on 2026-10-12.

What was the highest median Air Quality Index (US EPA) in Jefferson County?

60 in 2005, the highest value since 1980 in this series.

Related statistics for Jefferson County

All statistics for Jefferson County | Jefferson County in figures