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

Warren County had the highest share of days with good air quality (US EPA AQI) of 20 counties in 2007, at 87.7%. Scott County had the lowest, at 19.7%. The median was 55.2%. Source: EPA.

Highest87.7Warren County

Lowest19.7Scott County

Median55.220 counties

Map of counties, 2007

Under 40
40 to 50
50 to 64
64 to 80
80 and over
No data

%, 2007. 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, 2007

%. Source: Invokely calculation with data from EPA. Retrieved 2026-10-12.

Full ranking

Rank	Counties	2007 (%)	Change on 2006
1	Warren County	87.7	+2.8 pts
2	Cerro Gordo County	85.8	-0.5 pts
3	Story County	85	-3.6 pts
4	Harrison County	81.8	+13.1 pts
5	Palo Alto County	79.6	-1.8 pts
6	Linn County	72.3	-3 pts
7	Bremer County	72	-7.4 pts
8	Montgomery County	65.9	-8.4 pts
9	Van Buren County	63	-15.3 pts
10	Pottawattamie County	58	-1.8 pts
11	Wright County	52.4	-6.3 pts
12	Woodbury County	51.2	+1.2 pts
13	Delaware County	48.8	-51.2 pts
14	Johnson County	44.6	-2.1 pts
15	Polk County	43.1	-12.5 pts
16	Black Hawk County	40.3	-16.7 pts
17	Muscatine County	38.9	-4 pts
18	Clinton County	34.6	-21.1 pts
19	Lee County	33.9	-66.1 pts
20	Scott County	19.7	-9.3 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. 6 counties with data in other periods have no value for 2007 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), 2007) [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), 2007. 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=2007. 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), 2007. 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=2007.

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), 2007 [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=2007 (Accessed: 12 October 2026).

BibTeX

@misc{environmental_counties_in_iowa_by_2007,
  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), 2007}},
  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=2007. 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), 2007
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=2007
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/good-air-quality-days-share/iowa-counties?period=2007.
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  -

Embed this chart

Paste this code into a web page or a blog post. The chart shows the latest figures as they are published, with the source and a link back to this page.

Embed code

<iframe src="https://invokely.ai/embed/rankings/good-air-quality-days-share/iowa-counties?period=2007" width="760" height="500" title="Counties in Iowa by share of days with good air quality (US EPA AQI), 2007, chart from Invokely" loading="lazy" style="border:0;width:100%;max-width:760px" referrerpolicy="strict-origin-when-cross-origin"></iframe>

Sites that read oEmbed links, such as WordPress, can show the chart when you paste the link to this page.

Use this data in your AI agent

Invokely serves this figure to AI assistants through MCP and to code through a REST API, with the source and citation attached. Ask your assistant:

Rank Counties in Iowa by share of days with good air quality (US EPA AQI) using official data, and cite the source.

rank_places {"indicator":"aqi_good_days_share","level":"province","within":"Iowa","limit":10}
GET https://invokely.ai/api/v1/rank?indicator=aqi_good_days_share&level=province&within=Iowa&limit=10

Connect Claude, ChatGPT or Cursor in one step. The trial answers 25 calls a day without an account.

Questions

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

Warren County, with 87.7% in 2007, according to EPA.

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

Scott County, with 19.7% in 2007.

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. 6 counties have no value for 2007 and are not ranked.