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

Highest daily Air Quality Index (US EPA) in Lake County was 108 in 2025, according to the U.S. Environmental Protection Agency. That is down 32 from 2024. That is the 17th highest of 23 counties in 2025.

2025, index108
Change on 2024-32
Series high2491980
Series low1052008

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

10015020025019801987199420012008201520251980: 249 index1981: 217 index1982: 185 index1983: 227 index1984: 234 index1985: 208 index1986: 159 index1987: 246 index1988: 240 index1989: 202 index1990: 164 index1991: 201 index1992: 218 index1993: 154 index1994: 214 index1995: 203 index1996: 205 index1997: 207 index1998: 202 index1999: 169 index2000: 136 index2001: 174 index2002: 212 index2003: 147 index2004: 147 index2005: 179 index2006: 150 index2007: 154 index2008: 105 index2009: 154 index2010: 156 index2011: 174 index2012: 195 index2013: 136 index2014: 129 index2015: 122 index2016: 140 index2017: 129 index2018: 164 index2019: 115 index2020: 185 index2021: 136 index2022: 159 index2023: 179 index2024: 140 index2025: 108 index10015020025019801996201220251980: 249 index1981: 217 index1982: 185 index1983: 227 index1984: 234 index1985: 208 index1986: 159 index1987: 246 index1988: 240 index1989: 202 index1990: 164 index1991: 201 index1992: 218 index1993: 154 index1994: 214 index1995: 203 index1996: 205 index1997: 207 index1998: 202 index1999: 169 index2000: 136 index2001: 174 index2002: 212 index2003: 147 index2004: 147 index2005: 179 index2006: 150 index2007: 154 index2008: 105 index2009: 154 index2010: 156 index2011: 174 index2012: 195 index2013: 136 index2014: 129 index2015: 122 index2016: 140 index2017: 129 index2018: 164 index2019: 115 index2020: 185 index2021: 136 index2022: 159 index2023: 179 index2024: 140 index2025: 108 index
index. Source: EPA, EPA AirData annual AQI by county: highest daily AQI. Retrieved 2026-10-12, published 2026-07-13.
All 46 values
Periodindex
2025108
2024140
2023179
2022159
2021136
2020185
2019115
2018164
2017129
2016140
2015122
2014129
2013136
2012195
2011174
2010156
2009154
2008105
2007154
2006150
2005179
2004147
2003147
2002212
2001174
2000136
1999169
1998202
1997207
1996205
1995203
1994214
1993154
1992218
1991201
1990164
1989202
1988240
1987246
1986159
1985208
1984234
1983227
1982185
1981217
1980249

Lake County compared with nearby places

Adams County: 71 indexChampaign County: 138 indexClark County: 87 indexCook County: 168 indexDuPage County: 158 indexEffingham County: 84 indexHamilton County: 98 indexJersey County: 156 indexJo Daviess County: 87 indexKane County: 165 indexLake County: 108 indexMcHenry County: 165 indexMcLean County: 154 indexMacon County: 141 indexMacoupin County: 105 indexMadison County: 260 indexPeoria County: 154 indexRandolph County: 161 indexRock Island County: 167 indexSt. Clair County: 161 indexSangamon County: 142 indexWill County: 156 indexWinnebago County: 169 index
  • Under 100
  • 100 to 140
  • 140 to 160
  • 160 to 170
  • 170 and over
  • No data
Highest daily Air Quality Index (US EPA), 2025, index. Lake 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

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), Lake 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), Lake 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/lake-county-illinois. 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), Lake 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/lake-county-illinois.

Harvard

U.S. Environmental Protection Agency (2026) EPA AirData annual AQI by county: highest daily AQI, Highest daily Air Quality Index (US EPA), Lake 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/lake-county-illinois (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), Lake 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/lake-county-illinois. 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), Lake 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/lake-county-illinois
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/en/highest-daily-air-quality-index/lake-county-illinois.
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 Lake County?

Highest daily Air Quality Index (US EPA) in Lake County was 108 in 2025, according to the U.S. Environmental Protection Agency. That is down 32 from 2024. That is the 17th highest of 23 counties in 2025.

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 Lake County?

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

Related statistics for Lake County

All statistics for Lake County | Lake County in figures