Median Air Quality Index (US EPA) in Custer County
Median Air Quality Index (US EPA) in Custer County was 14 in 2019, according to the U.S. Environmental Protection Agency. That is down 2 from 2018. That is the 25th highest of 25 counties in 2018.
Median Air Quality Index (US EPA) in Custer County, 1997 to 2019
All 14 values
| Period | index |
|---|---|
| 2019 | 14 |
| 2018 | 16 |
| 2017 | 17 |
| 2016 | 15 |
| 2015 | 15 |
| 2005 | 17 |
| 2004 | 17 |
| 2003 | 19 |
| 2002 | 37 |
| 2001 | 41 |
| 2000 | 45 |
| 1999 | 47 |
| 1998 | 31 |
| 1997 | 15 |
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. 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.
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
APA 7
U.S. Environmental Protection Agency. (2026). EPA AirData annual AQI by county: median daily AQI (Median Air Quality Index (US EPA), Custer County, 1997 to 2019) [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), Custer County, 1997 to 2019. 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/custer-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), Custer County, 1997 to 2019. 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/custer-county-oklahoma.
Harvard
U.S. Environmental Protection Agency (2026) EPA AirData annual AQI by county: median daily AQI, Median Air Quality Index (US EPA), Custer County, 1997 to 2019 [Dataset]. Available at: https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual, via Invokely: https://invokely.ai/en/median-air-quality-index/custer-county-oklahoma (Accessed: 12 October 2026).
BibTeX
@misc{environmental_median_air_quality_index_2019,
author = {{U.S. Environmental Protection Agency}},
title = {{EPA AirData annual AQI by county: median daily AQI: Median Air Quality Index (US EPA), Custer County, 1997 to 2019}},
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/custer-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), Custer County, 1997 to 2019
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/custer-county-oklahoma
Y2 - 2026/10/12
N1 - Accessed via Invokely, https://invokely.ai/en/median-air-quality-index/custer-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 -
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:
What is the latest median Air Quality Index (US EPA) in Custer County? Cite the source.
get_value {"indicator":"aqi_median","place":"us-county-40039"}
GET https://invokely.ai/api/v1/value?indicator=aqi_median&place=us-county-40039Questions
What is the median Air Quality Index (US EPA) in Custer County?
Median Air Quality Index (US EPA) in Custer County was 14 in 2019, according to the U.S. Environmental Protection Agency. That is down 2 from 2018. That is the 25th highest of 25 counties in 2018.
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 Custer County?
47 in 1999, the highest value since 1997 in this series.
Related statistics for Custer County
- Expected annual loss from natural hazards (FEMA National Risk Index)
- Social vulnerability score (FEMA National Risk Index)
- Share of days unhealthy for sensitive groups or worse (US EPA AQI)
- Highest daily Air Quality Index (US EPA)
- Gross domestic product (GDP), US dollars
- GDP per capita, US dollars
- Real GDP growth
- Housing units