Share of days unhealthy for sensitive groups or worse (US EPA AQI) in Custer County
Share of days unhealthy for sensitive groups or worse (US EPA AQI) in Custer County was 0% in 1980, according to EPA.
All 1 values
| Period | % |
|---|---|
| 1980 | 0 |
Custer County compared with nearby places
- Under 0.6
- 0.6 to 1.1
- 1.1 to 6.4
- 6.4 and over
- No data
Rankings
Definition
Days with a daily Air Quality Index above 100 (unhealthy for sensitive groups, unhealthy, very unhealthy or hazardous) 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; the counts are stored with each value.
Use the share rather than the number of days to compare counties, since the days with an AQI differ. 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: days with an AQI above 100 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
APA 7
U.S. Environmental Protection Agency. (2026). EPA AirData annual AQI by county: days with an AQI above 100 as a share of days with an AQI, calculated with stored counts (Share of days unhealthy for sensitive groups or worse (US EPA AQI), Custer County, 1980) [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: days with an AQI above 100 as a share of days with an AQI, calculated with stored counts, Share of days unhealthy for sensitive groups or worse (US EPA AQI), Custer County, 1980. U.S. Environmental Protection Agency, 13 July 2026, https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual. Invokely, https://invokely.ai/en/unhealthy-air-quality-days-share/custer-county-nebraska. Accessed 12 Oct. 2026.
Chicago (author-date)
U.S. Environmental Protection Agency. 2026. EPA AirData annual AQI by county: days with an AQI above 100 as a share of days with an AQI, calculated with stored counts. Share of days unhealthy for sensitive groups or worse (US EPA AQI), Custer County, 1980. Dataset. Accessed October 12, 2026. https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual. Also distributed by Invokely, https://invokely.ai/en/unhealthy-air-quality-days-share/custer-county-nebraska.
Harvard
U.S. Environmental Protection Agency (2026) EPA AirData annual AQI by county: days with an AQI above 100 as a share of days with an AQI, calculated with stored counts, Share of days unhealthy for sensitive groups or worse (US EPA AQI), Custer County, 1980 [Dataset]. Available at: https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual, via Invokely: https://invokely.ai/en/unhealthy-air-quality-days-share/custer-county-nebraska (Accessed: 12 October 2026).
BibTeX
@misc{environmental_share_of_days_unhealthy_1980,
author = {{U.S. Environmental Protection Agency}},
title = {{EPA AirData annual AQI by county: days with an AQI above 100 as a share of days with an AQI, calculated with stored counts: Share of days unhealthy for sensitive groups or worse (US EPA AQI), Custer County, 1980}},
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/unhealthy-air-quality-days-share/custer-county-nebraska. Publisher attribution: U.S. Environmental Protection Agency, Air Quality System, AirData. EPA AirData annual AQI by county: days with an AQI above 100 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: days with an AQI above 100 as a share of days with an AQI, calculated with stored counts: Share of days unhealthy for sensitive groups or worse (US EPA AQI), Custer County, 1980
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/unhealthy-air-quality-days-share/custer-county-nebraska
Y2 - 2026/10/12
N1 - Accessed via Invokely, https://invokely.ai/en/unhealthy-air-quality-days-share/custer-county-nebraska.
N1 - Publisher attribution: U.S. Environmental Protection Agency, Air Quality System, AirData. EPA AirData annual AQI by county: days with an AQI above 100 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 -
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 share of days unhealthy for sensitive groups or worse (US EPA AQI) in Custer County? Cite the source.
get_value {"indicator":"aqi_unhealthy_sensitive_or_worse_days_share","place":"us-county-31041"}
GET https://invokely.ai/api/v1/value?indicator=aqi_unhealthy_sensitive_or_worse_days_share&place=us-county-31041Questions
What is the share of days unhealthy for sensitive groups or worse (US EPA AQI) in Custer County?
Share of days unhealthy for sensitive groups or worse (US EPA AQI) in Custer County was 0% in 1980, according to EPA.
Where does this figure come from?
U.S. Environmental Protection Agency. EPA AirData annual AQI by county: days with an AQI above 100 as a share of days with an AQI, calculated with stored counts. Retrieved by Invokely on 2026-10-12.