Data / Share of days with good air quality (US EPA AQI) / Will County

Share of days with good air quality (US EPA AQI) in Will County

Share of days with good air quality (US EPA AQI) in Will County was 61.6% in 2025, according to EPA. That is down 5.5 pts from 2024. That is the 19th highest of 23 counties in 2025.

202561.6%
Change on 2024-5.5 pts
Rank19th of 23Counties in Illinois ranked
Series high932011
Series low422015

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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Share of days with good air quality (US EPA AQI) in Will County, 1980 to 2025

40608010019801987199420012008201520251980: 73.4 %1981: 75.8 %1982: 81.2 %1983: 78.6 %1984: 80.6 %1985: 78.6 %1986: 83 %1987: 80.6 %1988: 64.5 %1989: 78.6 %1990: 86.5 %1991: 82.4 %1992: 88.7 %1993: 90.4 %1994: 86.5 %1995: 83.7 %1996: 82 %1997: 84.7 %1998: 75.9 %1999: 68.8 %2000: 63.4 %2001: 60.4 %2002: 59.2 %2003: 72.3 %2004: 80.3 %2005: 65.1 %2006: 79.1 %2007: 78.5 %2008: 87 %2009: 86.3 %2010: 83.2 %2011: 93 %2012: 84.4 %2013: 74.2 %2014: 47.2 %2015: 42 %2016: 55.1 %2017: 63.3 %2018: 53.2 %2019: 49 %2020: 50.4 %2021: 43 %2022: 52.9 %2023: 42.5 %2024: 67.1 %2025: 61.6 %40608010019801996201220251980: 73.4 %1981: 75.8 %1982: 81.2 %1983: 78.6 %1984: 80.6 %1985: 78.6 %1986: 83 %1987: 80.6 %1988: 64.5 %1989: 78.6 %1990: 86.5 %1991: 82.4 %1992: 88.7 %1993: 90.4 %1994: 86.5 %1995: 83.7 %1996: 82 %1997: 84.7 %1998: 75.9 %1999: 68.8 %2000: 63.4 %2001: 60.4 %2002: 59.2 %2003: 72.3 %2004: 80.3 %2005: 65.1 %2006: 79.1 %2007: 78.5 %2008: 87 %2009: 86.3 %2010: 83.2 %2011: 93 %2012: 84.4 %2013: 74.2 %2014: 47.2 %2015: 42 %2016: 55.1 %2017: 63.3 %2018: 53.2 %2019: 49 %2020: 50.4 %2021: 43 %2022: 52.9 %2023: 42.5 %2024: 67.1 %2025: 61.6 %
%. Source: Invokely calculation with data from EPA. Retrieved 2026-10-12, published 2026-07-13.
All 46 values
Period%
202561.6
202467.1
202342.5
202252.9
202143
202050.4
201949
201853.2
201763.3
201655.1
201542
201447.2
201374.2
201284.4
201193
201083.2
200986.3
200887
200778.5
200679.1
200565.1
200480.3
200372.3
200259.2
200160.4
200063.4
199968.8
199875.9
199784.7
199682
199583.7
199486.5
199390.4
199288.7
199182.4
199086.5
198978.6
198864.5
198780.6
198683
198578.6
198480.6
198378.6
198281.2
198175.8
198073.4

Will County compared with nearby places

Adams County: 94.7 %Champaign County: 65.8 %Clark County: 93.8 %Cook County: 40.8 %DuPage County: 63.8 %Effingham County: 95.5 %Hamilton County: 67.9 %Jersey County: 72.3 %Jo Daviess County: 95.3 %Kane County: 61.9 %Lake County: 84.8 %McHenry County: 67.9 %McLean County: 66 %Macon County: 64.9 %Macoupin County: 91.8 %Madison County: 52.3 %Peoria County: 59.9 %Randolph County: 68.1 %Rock Island County: 66.8 %St. Clair County: 58.4 %Sangamon County: 70.1 %Will County: 61.6 %Winnebago County: 68.7 %
  • Under 62
  • 62 to 66
  • 66 to 68
  • 68 to 89
  • 89 and over
  • No data
Share of days with good air quality (US EPA AQI), 2025, %. Will 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

Days with a daily Air Quality Index of 0 to 50 (good) as a percentage of the days of the year with an AQI in a US county. Calculated by Invokely from the day counts in the EPA AirData annual summaries; both counts are stored with each value.

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: good days as a share of days with an AQI, calculated with stored counts. 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: good days as a share of days with an AQI, calculated with stored counts (Share of days with good air quality (US EPA AQI), Will 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: good days as a share of days with an AQI, calculated with stored counts, Share of days with good air quality (US EPA AQI), Will 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/good-air-quality-days-share/will-county-illinois. Accessed 12 Oct. 2026.

Chicago (author-date)

U.S. Environmental Protection Agency. 2026. EPA AirData annual AQI by county: good days as a share of days with an AQI, calculated with stored counts. Share of days with good air quality (US EPA AQI), Will 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/good-air-quality-days-share/will-county-illinois.

Harvard

U.S. Environmental Protection Agency (2026) EPA AirData annual AQI by county: good days as a share of days with an AQI, calculated with stored counts, Share of days with good air quality (US EPA AQI), Will County, 1980 to 2025 [Dataset]. Available at: https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual, via Invokely: https://invokely.ai/en/good-air-quality-days-share/will-county-illinois (Accessed: 12 October 2026).

BibTeX
@misc{environmental_share_of_days_with_2025,
  author = {{U.S. Environmental Protection Agency}},
  title = {{EPA AirData annual AQI by county: good days as a share of days with an AQI, calculated with stored counts: Share of days with good air quality (US EPA AQI), Will 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/good-air-quality-days-share/will-county-illinois. Publisher attribution: U.S. Environmental Protection Agency, Air Quality System, AirData. EPA AirData annual AQI by county: good days as a share of days with an AQI, calculated with stored counts. 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: good days as a share of days with an AQI, calculated with stored counts: Share of days with good air quality (US EPA AQI), Will 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/good-air-quality-days-share/will-county-illinois
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/en/good-air-quality-days-share/will-county-illinois.
N1  - Publisher attribution: U.S. Environmental Protection Agency, Air Quality System, AirData. EPA AirData annual AQI by county: good days as a share of days with an AQI, calculated with stored counts. https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual. Retrieved 2026-10-12.
ER  -
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Questions

What is the share of days with good air quality (US EPA AQI) in Will County?

Share of days with good air quality (US EPA AQI) in Will County was 61.6% in 2025, according to EPA. That is down 5.5 pts from 2024. That is the 19th highest of 23 counties in 2025.

Where does this figure come from?

U.S. Environmental Protection Agency. EPA AirData annual AQI by county: good days as a share of days with an AQI, calculated with stored counts. Retrieved by Invokely on 2026-10-12.

What was the highest share of days with good air quality (US EPA AQI) in Will County?

93% in 2011, the highest value since 1980 in this series.

Related statistics for Will County

All statistics for Will County | Will County in figures