# Share of days unhealthy for sensitive groups or worse (US EPA AQI) in District of Columbia

Share of days unhealthy for sensitive groups or worse (US EPA AQI) in District of Columbia was 1.1% in 2025. Source: U.S. Environmental Protection Agency.

- Indicator id: `aqi_unhealthy_sensitive_or_worse_days_share`
- Place id: `us-county-11001`
- Unit: %
- 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.
- Note: 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.
- Source: 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 (https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual)
- Retrieved: 2026-10-12
- License: Public domain (US government work, 17 U.S.C. 105); citation requested
- Citation: 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.
- Web page: https://invokely.ai/en/unhealthy-air-quality-days-share/district-of-columbia-district-of-columbia
- API: https://invokely.ai/api/v1/series?indicator=aqi_unhealthy_sensitive_or_worse_days_share&place=us-county-11001

| Period | % |
|---|---:|
| 2025 | 1.1 |
| 2024 | 1.1 |
| 2023 | 3.3 |
| 2022 | 1.1 |
| 2021 | 2.2 |
| 2020 | 0.3 |
| 2019 | 1.4 |
| 2018 | 1.6 |
| 2017 | 1.1 |
| 2016 | 1.9 |
| 2015 | 1.4 |
| 2014 | 1.1 |
| 2013 | 0.3 |
| 2012 | 7.7 |
| 2011 | 4.4 |
| 2010 | 9.6 |
| 2009 | 2.5 |
| 2008 | 4.4 |
| 2007 | 8.5 |
| 2006 | 9.6 |
| 2005 | 8.2 |
| 2004 | 5.5 |
| 2003 | 6.6 |
| 2002 | 13.2 |
| 2001 | 11 |
| 2000 | 10.1 |
| 1999 | 16.2 |
| 1998 | 15.1 |
| 1997 | 11.5 |
| 1996 | 8.5 |
| 1995 | 14.8 |
| 1994 | 14.2 |
| 1993 | 13.2 |
| 1992 | 6 |
| 1991 | 12.9 |
| 1990 | 9.6 |
| 1989 | 8.7 |
| 1988 | 13 |
| 1987 | 15.3 |
| 1986 | 14.5 |
| 1985 | 14.9 |
| 1984 | 10.7 |
| 1983 | 16.7 |
| 1982 | 12.3 |
| 1981 | 12.3 |
| 1980 | 21.3 |