Data / Median Air Quality Index (US EPA) / Ellis County

Median Air Quality Index (US EPA) in Ellis County

Median Air Quality Index (US EPA) in Ellis County was 31 in 2015, according to the U.S. Environmental Protection Agency. That is down 1 from 2014.

2015, index31
Change on 2014-1
Series high382003
Series low242009

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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Median Air Quality Index (US EPA) in Ellis County, 2002 to 2015

202530354020022004200620082010201220152002: 34 index2003: 38 index2004: 33 index2005: 34 index2006: 27 index2007: 33 index2008: 28 index2009: 24 index2010: 27 index2011: 31 index2012: 33 index2013: 27 index2014: 32 index2015: 31 index20253035402002200720152002: 34 index2003: 38 index2004: 33 index2005: 34 index2006: 27 index2007: 33 index2008: 28 index2009: 24 index2010: 27 index2011: 31 index2012: 33 index2013: 27 index2014: 32 index2015: 31 index
index. Source: EPA, EPA AirData annual AQI by county: median daily AQI. Retrieved 2026-10-12, published 2026-07-13.
All 14 values
Periodindex
201531
201432
201327
201233
201131
201027
200924
200828
200733
200627
200534
200433
200338
200234

Ellis County compared with nearby places

Adair County: 44 indexCaddo County: 31 indexCanadian County: 37 indexCherokee County: 37 indexCleveland County: 45 indexComanche County: 44 indexCotton County: 39 indexCreek County: 36 indexCuster County: 15 indexDewey County: 42 indexEllis County: 31 indexJohnston County: 41 indexKay County: 53 indexLincoln County: 41 indexLove County: 34 indexMcClain County: 36 indexMayes County: 38 indexMuskogee County: 19 indexOklahoma County: 46 indexOttawa County: 50 indexPittsburg County: 41 indexSequoyah County: 36 indexTulsa County: 52 index
  • Under 35
  • 35 to 37
  • 37 to 41
  • 41 to 45
  • 45 and over
  • No data
Median Air Quality Index (US EPA), 2015, index. Ellis 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

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.

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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 (Median Air Quality Index (US EPA), Ellis County, 2002 to 2015) [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, Median Air Quality Index (US EPA), Ellis County, 2002 to 2015. U.S. Environmental Protection Agency, 13 July 2026, https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual. Invokely, https://invokely.ai/en/median-air-quality-index/ellis-county-oklahoma. Accessed 12 Oct. 2026.

Chicago (author-date)

U.S. Environmental Protection Agency. 2026. EPA AirData annual AQI by county: median daily AQI. Median Air Quality Index (US EPA), Ellis County, 2002 to 2015. Dataset. Accessed October 12, 2026. https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual. Also distributed by Invokely, https://invokely.ai/en/median-air-quality-index/ellis-county-oklahoma.

Harvard

U.S. Environmental Protection Agency (2026) EPA AirData annual AQI by county: median daily AQI, Median Air Quality Index (US EPA), Ellis County, 2002 to 2015 [Dataset]. Available at: https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual, via Invokely: https://invokely.ai/en/median-air-quality-index/ellis-county-oklahoma (Accessed: 12 October 2026).

BibTeX
@misc{environmental_median_air_quality_index_2015,
  author = {{U.S. Environmental Protection Agency}},
  title = {{EPA AirData annual AQI by county: median daily AQI: Median Air Quality Index (US EPA), Ellis County, 2002 to 2015}},
  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/median-air-quality-index/ellis-county-oklahoma. 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: Median Air Quality Index (US EPA), Ellis County, 2002 to 2015
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/median-air-quality-index/ellis-county-oklahoma
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/en/median-air-quality-index/ellis-county-oklahoma.
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

What is the median Air Quality Index (US EPA) in Ellis County?

Median Air Quality Index (US EPA) in Ellis County was 31 in 2015, according to the U.S. Environmental Protection Agency. That is down 1 from 2014.

Where does this figure come from?

U.S. Environmental Protection Agency. EPA AirData annual AQI by county: median daily AQI. Retrieved by Invokely on 2026-10-12.

What was the highest median Air Quality Index (US EPA) in Ellis County?

38 in 2003, the highest value since 2002 in this series.

Related statistics for Ellis County

All statistics for Ellis County | Ellis County in figures