# Highest daily Air Quality Index (US EPA) Highest daily Air Quality Index (AQI) value recorded in a US county during the year, from the EPA AirData annual summaries. Values above 500 are beyond the AQI scale and are published as EPA computes them. ## Key facts - Mono County had the highest highest daily Air Quality Index (US EPA) of 1000 counties in 2019, at 4,227, and Alexandria city the lowest, at 16. Source: the U.S. Environmental Protection Agency. - Published for 1,498 places, with figures from 1980 to 2025. - Figures last updated on 2026-10-12. - Indicator id: `aqi_max` - Unit: index - Note: A single day decides the value, so one wildfire or dust event can set it. Dust from the dry Owens Lake bed puts Inyo and Mono counties in California in the thousands. 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/highest-daily-air-quality-index - API: https://invokely.ai/api/v1/indicators/aqi_max ## Rankings - [US counties](https://invokely.ai/rankings/highest-daily-air-quality-index/us-counties.md) (1498 places) - [Counties in Texas](https://invokely.ai/rankings/highest-daily-air-quality-index/texas-counties.md) (63 places) - [Counties in North Carolina](https://invokely.ai/rankings/highest-daily-air-quality-index/north-carolina-counties.md) (62 places) - [Counties in Virginia](https://invokely.ai/rankings/highest-daily-air-quality-index/virginia-counties.md) (60 places) - [Counties in California](https://invokely.ai/rankings/highest-daily-air-quality-index/california-counties.md) (58 places) - [Counties in Ohio](https://invokely.ai/rankings/highest-daily-air-quality-index/ohio-counties.md) (58 places) - [Counties in Kentucky](https://invokely.ai/rankings/highest-daily-air-quality-index/kentucky-counties.md) (55 places) - [Counties in Indiana](https://invokely.ai/rankings/highest-daily-air-quality-index/indiana-counties.md) (53 places) - [Counties in Michigan](https://invokely.ai/rankings/highest-daily-air-quality-index/michigan-counties.md) (53 places) - [Counties in Wisconsin](https://invokely.ai/rankings/highest-daily-air-quality-index/wisconsin-counties.md) (48 places) - [Counties in Oklahoma](https://invokely.ai/rankings/highest-daily-air-quality-index/oklahoma-counties.md) (45 places) - [Counties in Pennsylvania](https://invokely.ai/rankings/highest-daily-air-quality-index/pennsylvania-counties.md) (44 places) - [Counties in Florida](https://invokely.ai/rankings/highest-daily-air-quality-index/florida-counties.md) (42 places) - [Counties in Tennessee](https://invokely.ai/rankings/highest-daily-air-quality-index/tennessee-counties.md) (42 places) - [Counties in Colorado](https://invokely.ai/rankings/highest-daily-air-quality-index/colorado-counties.md) (40 places) - [Counties in Minnesota](https://invokely.ai/rankings/highest-daily-air-quality-index/minnesota-counties.md) (40 places) - [Counties in Georgia](https://invokely.ai/rankings/highest-daily-air-quality-index/georgia-counties.md) (39 places) - [Counties in New York](https://invokely.ai/rankings/highest-daily-air-quality-index/new-york-counties.md) (39 places) - [Counties in Montana](https://invokely.ai/rankings/highest-daily-air-quality-index/montana-counties.md) (36 places) - [Counties in Missouri](https://invokely.ai/rankings/highest-daily-air-quality-index/missouri-counties.md) (34 places) - [Counties in Washington](https://invokely.ai/rankings/highest-daily-air-quality-index/washington-counties.md) (34 places) - [Counties in Illinois](https://invokely.ai/rankings/highest-daily-air-quality-index/illinois-counties.md) (33 places) - [Counties in Alabama](https://invokely.ai/rankings/highest-daily-air-quality-index/alabama-counties.md) (31 places) - [Counties in Idaho](https://invokely.ai/rankings/highest-daily-air-quality-index/idaho-counties.md) (31 places) - [Counties in Louisiana](https://invokely.ai/rankings/highest-daily-air-quality-index/louisiana-counties.md) (30 places) - [Counties in Mississippi](https://invokely.ai/rankings/highest-daily-air-quality-index/mississippi-counties.md) (29 places) - [Counties in South Carolina](https://invokely.ai/rankings/highest-daily-air-quality-index/south-carolina-counties.md) (28 places) - [Counties in Arkansas](https://invokely.ai/rankings/highest-daily-air-quality-index/arkansas-counties.md) (26 places) - [Counties in Iowa](https://invokely.ai/rankings/highest-daily-air-quality-index/iowa-counties.md) (26 places) - [Counties in Oregon](https://invokely.ai/rankings/highest-daily-air-quality-index/oregon-counties.md) (26 places) - [Counties in Nebraska](https://invokely.ai/rankings/highest-daily-air-quality-index/nebraska-counties.md) (24 places) - [Counties in Kansas](https://invokely.ai/rankings/highest-daily-air-quality-index/kansas-counties.md) (23 places) - [Counties in New Mexico](https://invokely.ai/rankings/highest-daily-air-quality-index/new-mexico-counties.md) (21 places) - [Counties in Wyoming](https://invokely.ai/rankings/highest-daily-air-quality-index/wyoming-counties.md) (21 places) - [Counties in New Jersey](https://invokely.ai/rankings/highest-daily-air-quality-index/new-jersey-counties.md) (20 places) - [Counties in West Virginia](https://invokely.ai/rankings/highest-daily-air-quality-index/west-virginia-counties.md) (20 places) - [Counties in Maryland](https://invokely.ai/rankings/highest-daily-air-quality-index/maryland-counties.md) (19 places) - [Counties in Utah](https://invokely.ai/rankings/highest-daily-air-quality-index/utah-counties.md) (19 places) - [Counties in Maine](https://invokely.ai/rankings/highest-daily-air-quality-index/maine-counties.md) (16 places) - [Counties in Arizona](https://invokely.ai/rankings/highest-daily-air-quality-index/arizona-counties.md) (15 places) - [Counties in North Dakota](https://invokely.ai/rankings/highest-daily-air-quality-index/north-dakota-counties.md) (15 places) - [Counties in South Dakota](https://invokely.ai/rankings/highest-daily-air-quality-index/south-dakota-counties.md) (14 places) - [Counties in Alaska](https://invokely.ai/rankings/highest-daily-air-quality-index/alaska-counties.md) (13 places) - [Counties in Massachusetts](https://invokely.ai/rankings/highest-daily-air-quality-index/massachusetts-counties.md) (13 places) - [Counties in Nevada](https://invokely.ai/rankings/highest-daily-air-quality-index/nevada-counties.md) (12 places) - [Counties in New Hampshire](https://invokely.ai/rankings/highest-daily-air-quality-index/new-hampshire-counties.md) (10 places) - [Counties in Vermont](https://invokely.ai/rankings/highest-daily-air-quality-index/vermont-counties.md) (7 places)