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

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

Share of days with good air quality (US EPA AQI) in Johnson County was 70.1% in 2025, according to EPA. That is down 0.7 pts from 2024.

202570.1%
Change on 2024-0.7 pts
Series high97.61991
Series low232010

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 Johnson County, 1980 to 2025

2040608010019801986199920052011201720251980: 94.3 %1981: 79.7 %1982: 84.5 %1983: 74.1 %1984: 78.8 %1985: 94.1 %1986: 92.1 %1987: 83.6 %1988: 78.9 %1989: 82.6 %1990: 85.8 %1991: 97.6 %1999: 38.8 %2000: 51.6 %2001: 44.6 %2002: 46.3 %2003: 44.6 %2004: 49.2 %2005: 35.2 %2006: 46.7 %2007: 44.6 %2008: 50 %2009: 38.2 %2010: 23 %2011: 25.8 %2012: 32.5 %2013: 43.8 %2014: 55.2 %2015: 54.2 %2016: 64.5 %2017: 59.3 %2018: 51.4 %2019: 57.7 %2020: 57.2 %2021: 47.3 %2022: 61.1 %2023: 39.2 %2024: 70.8 %2025: 70.1 %2040608010019802000201320251980: 94.3 %1981: 79.7 %1982: 84.5 %1983: 74.1 %1984: 78.8 %1985: 94.1 %1986: 92.1 %1987: 83.6 %1988: 78.9 %1989: 82.6 %1990: 85.8 %1991: 97.6 %1999: 38.8 %2000: 51.6 %2001: 44.6 %2002: 46.3 %2003: 44.6 %2004: 49.2 %2005: 35.2 %2006: 46.7 %2007: 44.6 %2008: 50 %2009: 38.2 %2010: 23 %2011: 25.8 %2012: 32.5 %2013: 43.8 %2014: 55.2 %2015: 54.2 %2016: 64.5 %2017: 59.3 %2018: 51.4 %2019: 57.7 %2020: 57.2 %2021: 47.3 %2022: 61.1 %2023: 39.2 %2024: 70.8 %2025: 70.1 %
%. Source: Invokely calculation with data from EPA. Retrieved 2026-10-12, published 2026-07-13.
All 39 values
Period%
202570.1
202470.8
202339.2
202261.1
202147.3
202057.2
201957.7
201851.4
201759.3
201664.5
201554.2
201455.2
201343.8
201232.5
201125.8
201023
200938.2
200850
200744.6
200646.7
200535.2
200449.2
200344.6
200246.3
200144.6
200051.6
199938.8
199197.6
199085.8
198982.6
198878.9
198783.6
198692.1
198594.1
198478.8
198374.1
198284.5
198179.7
198094.3

Johnson County compared with nearby places

Black Hawk County: 53.4 %Bremer County: 87.1 %Clinton County: 59.5 %Harrison County: 83.1 %Johnson County: 70.1 %Linn County: 61.4 %Montgomery County: 69.3 %Muscatine County: 66 %Palo Alto County: 72.3 %Polk County: 61.4 %Pottawattamie County: 70.3 %Scott County: 58.9 %Van Buren County: 64.8 %Webster County: 59.2 %Woodbury County: 79.6 %
  • Under 59
  • 59 to 63
  • 63 to 70
  • 70 to 74
  • 74 and over
  • No data
Share of days with good air quality (US EPA AQI), 2025, %. Johnson 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), Johnson 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), Johnson 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/johnson-county-iowa. 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), Johnson 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/johnson-county-iowa.

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), Johnson 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/johnson-county-iowa (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), Johnson 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/johnson-county-iowa. 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), Johnson 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/johnson-county-iowa
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/en/good-air-quality-days-share/johnson-county-iowa.
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 Johnson County?

Share of days with good air quality (US EPA AQI) in Johnson County was 70.1% in 2025, according to EPA. That is down 0.7 pts from 2024.

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 Johnson County?

97.6% in 1991, the highest value since 1980 in this series.

Related statistics for Johnson County

All statistics for Johnson County | Johnson County in figures