Highest daily Air Quality Index (US EPA) in Knox County

Highest daily Air Quality Index (US EPA) in Knox County was 156 in 2025, according to the U.S. Environmental Protection Agency. That is up 51 from 2024.

2025, index156

Change on 2024+51

Series high2421980

Series low772022

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

Highest daily Air Quality Index (US EPA) in Knox County, 1980 to 2025

index. Source: EPA, EPA AirData annual AQI by county: highest daily AQI. Retrieved 2026-10-12, published 2026-07-13.

All 46 values

Period	index
2025	156
2024	105
2023	149
2022	77
2021	150
2020	91
2019	84
2018	112
2017	100
2016	175
2015	101
2014	84
2013	87
2012	217
2011	119
2010	133
2009	129
2008	174
2007	215
2006	161
2005	166
2004	177
2003	187
2002	195
2001	187
2000	218
1999	207
1998	218
1997	206
1996	206
1995	202
1994	182
1993	200
1992	166
1991	177
1990	209
1989	136
1988	226
1987	190
1986	182
1985	156
1984	174
1983	172
1982	203
1981	200
1980	242

Knox County compared with nearby places

Under 73
73 to 89
89 to 100
100 to 130
130 and over
No data

Highest daily Air Quality Index (US EPA), 2025, index. Knox 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

Counties in Tennessee by highest daily Air Quality Index (US EPA) 42 places

Definition

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.

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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 (Highest daily Air Quality Index (US EPA), Knox 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: highest daily AQI, Highest daily Air Quality Index (US EPA), Knox 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/highest-daily-air-quality-index/knox-county-tennessee. Accessed 12 Oct. 2026.

Chicago (author-date)

U.S. Environmental Protection Agency. 2026. EPA AirData annual AQI by county: highest daily AQI. Highest daily Air Quality Index (US EPA), Knox 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/highest-daily-air-quality-index/knox-county-tennessee.

Harvard

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

BibTeX

@misc{environmental_highest_daily_air_quality_2025,
  author = {{U.S. Environmental Protection Agency}},
  title = {{EPA AirData annual AQI by county: highest daily AQI: Highest daily Air Quality Index (US EPA), Knox 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/highest-daily-air-quality-index/knox-county-tennessee. 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: Highest daily Air Quality Index (US EPA), Knox 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/highest-daily-air-quality-index/knox-county-tennessee
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/en/highest-daily-air-quality-index/knox-county-tennessee.
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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Questions

What is the highest daily Air Quality Index (US EPA) in Knox County?

Highest daily Air Quality Index (US EPA) in Knox County was 156 in 2025, according to the U.S. Environmental Protection Agency. That is up 51 from 2024.

Where does this figure come from?

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

What was the highest highest daily Air Quality Index (US EPA) in Knox County?

242 in 1980, the highest value since 1980 in this series.

Related statistics for Knox County

All statistics for Knox County | Knox County in figures