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

Knox County had the highest share of days with good air quality (US EPA AQI) of 13 counties in 2007, at 100%. Douglas County had the lowest, at 21.4%. The median was 78.5%. Source: EPA.

Highest100Knox County

Lowest21.4Douglas County

Median78.513 counties

Map of counties, 2007

Under 60
60 to 67
67 to 88
88 to 92
92 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	Knox County	100	+16.9 pts
2	Garden County	95.8	+0.8 pts
3	Thomas County	93.3	-2.2 pts
4	Lancaster County	89	-0.3 pts
5	Cass County	88.5	+5.5 pts
6	Dawson County	87.7	+7.1 pts
7	Scotts Bluff County	78.5	-11.4 pts
8	Hall County	66.7	-4.7 pts
8	Thurston County	66.7	-7.6 pts
10	Washington County	62.2	-2.8 pts
11	Sarpy County	58.4	-2.6 pts
12	Sioux County	53.8	n/a
13	Douglas County	21.4	-12.8 pts

Other periods

2008
2007
2002

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. 11 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 Nebraska 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 Nebraska 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/nebraska-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 Nebraska 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/nebraska-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 Nebraska 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/nebraska-counties?period=2007 (Accessed: 12 October 2026).

BibTeX

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

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Questions

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

Knox County, with 100% in 2007, according to EPA.

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

Douglas County, with 21.4% 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. 11 counties have no value for 2007 and are not ranked.