Data / Rankings / Median Air Quality Index (US EPA) / Counties in Iowa

Counties in Iowa by median Air Quality Index (US EPA)

Scott County had the highest median Air Quality Index (US EPA) of 20 counties in 2010, at 60. Delaware County had the lowest, at 15. The median was 46. Source: the U.S. Environmental Protection Agency.

Keep it in a collection in your library.
Highest60Scott County
Lowest15Delaware County
Median4620 counties

Map of counties, 2010

Black Hawk County: 52 indexBremer County: 38 indexCerro Gordo County: 18 indexClinton County: 59 indexDelaware County: 15 indexHarrison County: 40 indexJohnson County: 57 indexLee County: 53 indexLinn County: 53 indexMontgomery County: 49 indexMuscatine County: 57 indexPalo Alto County: 46 indexPolk County: 51 indexPottawattamie County: 32 indexScott County: 60 indexStory County: 36 indexTama County: 42 indexVan Buren County: 42 indexWarren County: 37 indexWoodbury County: 45 index
  • Under 37
  • 37 to 42
  • 42 to 50
  • 50 to 54
  • 54 and over
  • No data
index, 2010. Hatched areas have no value for this period. Source: EPA, EPA AirData annual AQI by county: median daily AQI. Boundaries: U.S. Census Bureau cartographic boundary files.

All counties, 2010

Scott County: 60 indexScott County60Clinton County: 59 indexClinton County59Johnson County: 57 indexJohnson County57Muscatine County: 57 indexMuscatine County57Lee County: 53 indexLee County53Linn County: 53 indexLinn County53Black Hawk County: 52 indexBlack Hawk County52Polk County: 51 indexPolk County51Montgomery County: 49 indexMontgomery County49Palo Alto County: 46 indexPalo Alto County46Woodbury County: 45 indexWoodbury County45Tama County: 42 indexTama County42Van Buren County: 42 indexVan Buren County42Harrison County: 40 indexHarrison County40Bremer County: 38 indexBremer County38Warren County: 37 indexWarren County37Story County: 36 indexStory County36Pottawattamie County: 32 indexPottawattamie County32Cerro Gordo County: 18 indexCerro Gordo County18Delaware County: 15 indexDelaware County15Scott County: 60 indexScott County60Clinton County: 59 indexClinton County59Johnson County: 57 indexJohnson County57Muscatine County: 57 indexMuscatine County57Lee County: 53 indexLee County53Linn County: 53 indexLinn County53Black Hawk County: 52 indexBlack Hawk County52Polk County: 51 indexPolk County51Montgomery County: 49 indexMontgomery County49Palo Alto County: 46 indexPalo Alto County46Woodbury County: 45 indexWoodbury County45Tama County: 42 indexTama County42Van Buren County: 42 indexVan Buren County42Harrison County: 40 indexHarrison County40Bremer County: 38 indexBremer County38Warren County: 37 indexWarren County37Story County: 36 indexStory County36Pottawattamie County: 32 indexPottawattamie County32Cerro Gordo County: 18 indexCerro Gordo County18Delaware County: 15 indexDelaware County15
index. Source: EPA, EPA AirData annual AQI by county: median daily AQI. Retrieved 2026-10-12.

Full ranking

RankCounties2010
index		Change on 2009
1Scott County60+4
2Clinton County59+3
3Johnson County57+4
3Muscatine County57+2
5Lee County53+1
5Linn County53+1
7Black Hawk County520
8Polk County51+2
9Montgomery County49+10
10Palo Alto County46+7
11Woodbury County45+3
12Tama County42n/a
12Van Buren County42+3
14Harrison County400
15Bremer County38+2
16Warren County37+1
17Story County36+1
18Pottawattamie County32+1
19Cerro Gordo County18-5
20Delaware County15+1

Other periods

About this ranking

Median of the daily Air Quality Index (AQI) values of a US county over the days of the year with an AQI, from the EPA AirData annual summaries.

More on how it is measured
  • The daily county AQI is the highest AQI among the monitors and pollutants reported that day (ozone, PM2.5, PM10, carbon monoxide and nitrogen dioxide).
  • Lower is cleaner: 0 to 50 is good, 51 to 100 moderate and above 100 unhealthy for sensitive groups.

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. 6 counties with data in other periods have no value for 2010 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: median 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: median daily AQI (Counties in Iowa by median Air Quality Index (US EPA), 2010) [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: median daily AQI, Counties in Iowa by median Air Quality Index (US EPA), 2010. U.S. Environmental Protection Agency, 13 July 2026, https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual. Invokely, https://invokely.ai/rankings/median-air-quality-index/iowa-counties?period=2010. Accessed 12 Oct. 2026.

Chicago (author-date)

U.S. Environmental Protection Agency. 2026. EPA AirData annual AQI by county: median daily AQI. Counties in Iowa by median Air Quality Index (US EPA), 2010. Dataset. Accessed October 12, 2026. https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual. Also distributed by Invokely, https://invokely.ai/rankings/median-air-quality-index/iowa-counties?period=2010.

Harvard

U.S. Environmental Protection Agency (2026) EPA AirData annual AQI by county: median daily AQI, Counties in Iowa by median Air Quality Index (US EPA), 2010 [Dataset]. Available at: https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual, via Invokely: https://invokely.ai/rankings/median-air-quality-index/iowa-counties?period=2010 (Accessed: 12 October 2026).

BibTeX
@misc{environmental_counties_in_iowa_by_2010,
  author = {{U.S. Environmental Protection Agency}},
  title = {{EPA AirData annual AQI by county: median daily AQI: Counties in Iowa by median Air Quality Index (US EPA), 2010}},
  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/median-air-quality-index/iowa-counties?period=2010. Publisher attribution: U.S. Environmental Protection Agency, Air Quality System, AirData. EPA AirData annual AQI by county: median 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: median daily AQI: Counties in Iowa by median Air Quality Index (US EPA), 2010
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/median-air-quality-index/iowa-counties?period=2010
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/median-air-quality-index/iowa-counties?period=2010.
N1  - Publisher attribution: U.S. Environmental Protection Agency, Air Quality System, AirData. EPA AirData annual AQI by county: median daily AQI. https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual. Retrieved 2026-10-12.
ER  -
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Questions

Which county has the highest median Air Quality Index (US EPA)?

Scott County, with 60 in 2010, according to the U.S. Environmental Protection Agency.

Which county has the lowest median Air Quality Index (US EPA)?

Delaware County, with 15 in 2010.

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: median daily AQI. Retrieved 2026-10-12. 6 counties have no value for 2010 and are not ranked.

Median Air Quality Index (US EPA): other rankings

Counties in Iowa: more rankings