# Share of days with good air quality (US EPA AQI) 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. ## Key facts - Alamosa County had the highest share of days with good air quality (US EPA AQI) of 1000 counties in 2019, at 100%, and San Bernardino County the lowest, at 7.9%. Source: EPA. - Published for 1,498 places, with figures from 1980 to 2025. - Figures last updated on 2026-10-12. - Indicator id: `aqi_good_days_share` - Unit: % - Note: 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. - Web page: https://invokely.ai/en/good-air-quality-days-share - API: https://invokely.ai/api/v1/indicators/aqi_good_days_share ## Rankings - [US counties](https://invokely.ai/rankings/good-air-quality-days-share/us-counties.md) (1498 places) - [Counties in Texas](https://invokely.ai/rankings/good-air-quality-days-share/texas-counties.md) (63 places) - [Counties in North Carolina](https://invokely.ai/rankings/good-air-quality-days-share/north-carolina-counties.md) (62 places) - [Counties in Virginia](https://invokely.ai/rankings/good-air-quality-days-share/virginia-counties.md) (60 places) - [Counties in California](https://invokely.ai/rankings/good-air-quality-days-share/california-counties.md) (58 places) - [Counties in Ohio](https://invokely.ai/rankings/good-air-quality-days-share/ohio-counties.md) (58 places) - [Counties in Kentucky](https://invokely.ai/rankings/good-air-quality-days-share/kentucky-counties.md) (55 places) - [Counties in Indiana](https://invokely.ai/rankings/good-air-quality-days-share/indiana-counties.md) (53 places) - [Counties in Michigan](https://invokely.ai/rankings/good-air-quality-days-share/michigan-counties.md) (53 places) - [Counties in Wisconsin](https://invokely.ai/rankings/good-air-quality-days-share/wisconsin-counties.md) (48 places) - [Counties in Oklahoma](https://invokely.ai/rankings/good-air-quality-days-share/oklahoma-counties.md) (45 places) - [Counties in Pennsylvania](https://invokely.ai/rankings/good-air-quality-days-share/pennsylvania-counties.md) (44 places) - [Counties in Florida](https://invokely.ai/rankings/good-air-quality-days-share/florida-counties.md) (42 places) - [Counties in Tennessee](https://invokely.ai/rankings/good-air-quality-days-share/tennessee-counties.md) (42 places) - [Counties in Colorado](https://invokely.ai/rankings/good-air-quality-days-share/colorado-counties.md) (40 places) - [Counties in Minnesota](https://invokely.ai/rankings/good-air-quality-days-share/minnesota-counties.md) (40 places) - [Counties in Georgia](https://invokely.ai/rankings/good-air-quality-days-share/georgia-counties.md) (39 places) - [Counties in New York](https://invokely.ai/rankings/good-air-quality-days-share/new-york-counties.md) (39 places) - [Counties in Montana](https://invokely.ai/rankings/good-air-quality-days-share/montana-counties.md) (36 places) - [Counties in Missouri](https://invokely.ai/rankings/good-air-quality-days-share/missouri-counties.md) (34 places) - [Counties in Washington](https://invokely.ai/rankings/good-air-quality-days-share/washington-counties.md) (34 places) - [Counties in Illinois](https://invokely.ai/rankings/good-air-quality-days-share/illinois-counties.md) (33 places) - [Counties in Alabama](https://invokely.ai/rankings/good-air-quality-days-share/alabama-counties.md) (31 places) - [Counties in Idaho](https://invokely.ai/rankings/good-air-quality-days-share/idaho-counties.md) (31 places) - [Counties in Louisiana](https://invokely.ai/rankings/good-air-quality-days-share/louisiana-counties.md) (30 places) - [Counties in Mississippi](https://invokely.ai/rankings/good-air-quality-days-share/mississippi-counties.md) (29 places) - [Counties in South Carolina](https://invokely.ai/rankings/good-air-quality-days-share/south-carolina-counties.md) (28 places) - [Counties in Arkansas](https://invokely.ai/rankings/good-air-quality-days-share/arkansas-counties.md) (26 places) - [Counties in Iowa](https://invokely.ai/rankings/good-air-quality-days-share/iowa-counties.md) (26 places) - [Counties in Oregon](https://invokely.ai/rankings/good-air-quality-days-share/oregon-counties.md) (26 places) - [Counties in Nebraska](https://invokely.ai/rankings/good-air-quality-days-share/nebraska-counties.md) (24 places) - [Counties in Kansas](https://invokely.ai/rankings/good-air-quality-days-share/kansas-counties.md) (23 places) - [Counties in New Mexico](https://invokely.ai/rankings/good-air-quality-days-share/new-mexico-counties.md) (21 places) - [Counties in Wyoming](https://invokely.ai/rankings/good-air-quality-days-share/wyoming-counties.md) (21 places) - [Counties in New Jersey](https://invokely.ai/rankings/good-air-quality-days-share/new-jersey-counties.md) (20 places) - [Counties in West Virginia](https://invokely.ai/rankings/good-air-quality-days-share/west-virginia-counties.md) (20 places) - [Counties in Maryland](https://invokely.ai/rankings/good-air-quality-days-share/maryland-counties.md) (19 places) - [Counties in Utah](https://invokely.ai/rankings/good-air-quality-days-share/utah-counties.md) (19 places) - [Counties in Maine](https://invokely.ai/rankings/good-air-quality-days-share/maine-counties.md) (16 places) - [Counties in Arizona](https://invokely.ai/rankings/good-air-quality-days-share/arizona-counties.md) (15 places) - [Counties in North Dakota](https://invokely.ai/rankings/good-air-quality-days-share/north-dakota-counties.md) (15 places) - [Counties in South Dakota](https://invokely.ai/rankings/good-air-quality-days-share/south-dakota-counties.md) (14 places) - [Counties in Alaska](https://invokely.ai/rankings/good-air-quality-days-share/alaska-counties.md) (13 places) - [Counties in Massachusetts](https://invokely.ai/rankings/good-air-quality-days-share/massachusetts-counties.md) (13 places) - [Counties in Nevada](https://invokely.ai/rankings/good-air-quality-days-share/nevada-counties.md) (12 places) - [Counties in New Hampshire](https://invokely.ai/rankings/good-air-quality-days-share/new-hampshire-counties.md) (10 places) - [Counties in Vermont](https://invokely.ai/rankings/good-air-quality-days-share/vermont-counties.md) (7 places)