Data / Rankings / Share of days with good air quality (US EPA AQI) / Counties in Iowa

Counties in Iowa by share of days with good air quality (US EPA AQI)

Cerro Gordo County had the highest share of days with good air quality (US EPA AQI) of 19 counties in 2013, at 99.4%. Scott County had the lowest, at 18.9%. The median was 53.5%. Source: EPA.

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Highest99.4Cerro Gordo County
Lowest18.9Scott County
Median53.519 counties

Map of counties, 2013

Black Hawk County: 43 %Bremer County: 93.8 %Cerro Gordo County: 99.4 %Clinton County: 22.2 %Delaware County: 58.8 %Harrison County: 86.4 %Johnson County: 43.8 %Lee County: 45.5 %Linn County: 46.6 %Montgomery County: 51.2 %Muscatine County: 27.4 %Palo Alto County: 60.3 %Polk County: 52.3 %Pottawattamie County: 53.5 %Scott County: 18.9 %Story County: 91.6 %Van Buren County: 56.2 %Warren County: 90.6 %Woodbury County: 64.8 %
  • Under 43
  • 43 to 51
  • 51 to 58
  • 58 to 88
  • 88 and over
  • No data
%, 2013. Hatched areas have no value for this period. Source: Invokely calculation with data from EPA. Boundaries: U.S. Census Bureau cartographic boundary files.

All counties, 2013

Cerro Gordo County: 99.4 %Cerro Gordo County99.4Bremer County: 93.8 %Bremer County93.8Story County: 91.6 %Story County91.6Warren County: 90.6 %Warren County90.6Harrison County: 86.4 %Harrison County86.4Woodbury County: 64.8 %Woodbury County64.8Palo Alto County: 60.3 %Palo Alto County60.3Delaware County: 58.8 %Delaware County58.8Van Buren County: 56.2 %Van Buren County56.2Pottawattamie County: 53.5 %Pottawattamie County53.5Polk County: 52.3 %Polk County52.3Montgomery County: 51.2 %Montgomery County51.2Linn County: 46.6 %Linn County46.6Lee County: 45.5 %Lee County45.5Johnson County: 43.8 %Johnson County43.8Black Hawk County: 43 %Black Hawk County43Muscatine County: 27.4 %Muscatine County27.4Clinton County: 22.2 %Clinton County22.2Scott County: 18.9 %Scott County18.9Cerro Gordo County: 99.4 %Cerro Gordo County99.4Bremer County: 93.8 %Bremer County93.8Story County: 91.6 %Story County91.6Warren County: 90.6 %Warren County90.6Harrison County: 86.4 %Harrison County86.4Woodbury County: 64.8 %Woodbury County64.8Palo Alto County: 60.3 %Palo Alto County60.3Delaware County: 58.8 %Delaware County58.8Van Buren County: 56.2 %Van Buren County56.2Pottawattamie County: 53.5 %Pottawattamie County53.5Polk County: 52.3 %Polk County52.3Montgomery County: 51.2 %Montgomery County51.2Linn County: 46.6 %Linn County46.6Lee County: 45.5 %Lee County45.5Johnson County: 43.8 %Johnson County43.8Black Hawk County: 43 %Black Hawk County43Muscatine County: 27.4 %Muscatine County27.4Clinton County: 22.2 %Clinton County22.2Scott County: 18.9 %Scott County18.9
%. Source: Invokely calculation with data from EPA. Retrieved 2026-10-12.

Full ranking

RankCounties2013 (%)Change on 2012
1Cerro Gordo County99.4+2.8 pts
2Bremer County93.8+19.6 pts
3Story County91.6+9.8 pts
4Warren County90.6+15.8 pts
5Harrison County86.4+22.7 pts
6Woodbury County64.8+8.7 pts
7Palo Alto County60.3+4.8 pts
8Delaware County58.8-1.7 pts
9Van Buren County56.2+5.9 pts
10Pottawattamie County53.5+11.4 pts
11Polk County52.3+6.1 pts
12Montgomery County51.2+1.1 pts
13Linn County46.6+3.2 pts
14Lee County45.5+1.4 pts
15Johnson County43.8+11.3 pts
16Black Hawk County43-1.2 pts
17Muscatine County27.4-6.5 pts
18Clinton County22.2+3.1 pts
19Scott County18.9+0.6 pts

Other periods

About this ranking

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.

Every value in the ranking comes from the same publisher and the same period, so the counties are compared on one definition. 7 counties with data in other periods have no value for 2013 and are left out rather than filled from another source. Equal values share a rank.

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 (Counties in Iowa by share of days with good air quality (US EPA AQI), 2013) [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, Counties in Iowa by share of days with good air quality (US EPA AQI), 2013. U.S. Environmental Protection Agency, 13 July 2026, https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual. Invokely, https://invokely.ai/rankings/good-air-quality-days-share/iowa-counties?period=2013. 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. Counties in Iowa by share of days with good air quality (US EPA AQI), 2013. Dataset. Accessed October 12, 2026. https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual. Also distributed by Invokely, https://invokely.ai/rankings/good-air-quality-days-share/iowa-counties?period=2013.

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, Counties in Iowa by share of days with good air quality (US EPA AQI), 2013 [Dataset]. Available at: https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual, via Invokely: https://invokely.ai/rankings/good-air-quality-days-share/iowa-counties?period=2013 (Accessed: 12 October 2026).

BibTeX
@misc{environmental_counties_in_iowa_by_2013,
  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: Counties in Iowa by share of days with good air quality (US EPA AQI), 2013}},
  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/rankings/good-air-quality-days-share/iowa-counties?period=2013. 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: Counties in Iowa by share of days with good air quality (US EPA AQI), 2013
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/rankings/good-air-quality-days-share/iowa-counties?period=2013
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/good-air-quality-days-share/iowa-counties?period=2013.
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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Rank Counties in Iowa by share of days with good air quality (US EPA AQI) using official data, and cite the source.
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Questions

Which county has the highest share of days with good air quality (US EPA AQI)?

Cerro Gordo County, with 99.4% in 2013, according to EPA.

Which county has the lowest share of days with good air quality (US EPA AQI)?

Scott County, with 18.9% in 2013.

Where does this ranking come from?

Every value comes from one source and one period, so the places are comparable: 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 2026-10-12. 7 counties have no value for 2013 and are not ranked.

Share of days with good air quality (US EPA AQI): other rankings

Counties in Iowa: more rankings