790 monitored counties
Air quality by state and county
| State | Smoke days / yr | Worst smoke year | Bad-air days, typical county | Mold pros licensed |
|---|---|---|---|---|
| North Dakota | 49 | 2023 (74) | 8.8 | No |
| Minnesota | 47 | 2023 (79) | 5.8 | No |
| South Dakota | 43 | 2021 (62) | 4.6 | No |
| Iowa | 41 | 2023 (68) | 3.6 | No |
| Wisconsin | 41 | 2023 (77) | 5.7 | No |
| Montana | 40 | 2021 (58) | 5.6 | No |
| Michigan | 39 | 2023 (76) | 4 | No |
| Missouri | 36 | 2023 (63) | 2 | No |
| Nebraska | 36 | 2021 (58) | 1.4 | No |
| Illinois | 33 | 2023 (60) | 5 | Yes |
| Kansas | 32 | 2021 (51) | 3.6 | No |
| Arkansas | 31 | 2023 (58) | 2 | No |
| Indiana | 30 | 2023 (58) | 2.2 | No |
| Idaho | 29 | 2021 (60) | 5.4 | No |
| Wyoming | 29 | 2021 (63) | 2.6 | No |
| New York | 27 | 2023 (58) | 2.4 | Yes |
| Ohio | 27 | 2023 (56) | 3.4 | No |
| Oregon | 27 | 2021 (44) | 3.6 | No |
| Oklahoma | 26 | 2021 (41) | 4.6 | No |
| Vermont | 26 | 2023 (57) | 1.8 | No |
| Washington | 25 | 2021 (33) | 2.8 | No |
| Connecticut | 24 | 2023 (55) | 6.8 | No |
| Kentucky | 24 | 2023 (54) | 1 | No |
| Maine | 24 | 2023 (50) | 1.2 | No |
| New Jersey | 24 | 2023 (58) | 3.5 | No |
| Pennsylvania | 24 | 2023 (56) | 2.4 | No |
| Delaware | 23 | 2023 (56) | 2.8 | No |
| Massachusetts | 23 | 2023 (53) | 2 | No |
| New Hampshire | 23 | 2023 (52) | 1.8 | Yes |
| Rhode Island | 23 | 2023 (53) | 2 | No |
| District of Columbia | 22 | 2023 (51) | 6.4 | Yes |
| Louisiana | 22 | 2023 (48) | 1 | Yes |
| Maryland | 22 | 2023 (53) | 2.2 | No |
| Mississippi | 22 | 2023 (53) | 0.8 | No |
| Tennessee | 22 | 2023 (52) | 0.4 | No |
| West Virginia | 22 | 2023 (53) | 0.6 | No |
| Virginia | 20 | 2023 (48) | 1 | No |
| Alabama | 19 | 2023 (46) | 0.4 | No |
| Nevada | 17 | 2021 (58) | 4.6 | No |
| North Carolina | 17 | 2023 (41) | 0.6 | No |
| Texas | 17 | 2023 (27) | 3.2 | Yes |
| Colorado | 16 | 2021 (39) | 8 | No |
| Georgia | 16 | 2023 (39) | 2 | No |
| Utah | 16 | 2021 (46) | 6.6 | No |
| California | 15 | 2021 (45) | 9.6 | No |
| South Carolina | 15 | 2023 (36) | 0.8 | No |
| New Mexico | 11 | 2021 (29) | 5.6 | No |
| Florida | 8 | 2023 (18) | 0.2 | Yes |
| Arizona | 7 | 2021 (23) | 3.2 | No |
| Alaska | 6 | 2023 (10) | 0.8 | No |
| Hawaii | 0 | 2021 (0) | 0.2 | No |
Smoke days come from NOAA satellite analysts, who draw where smoke plumes are overhead each day. A plume overhead does not always reach the ground, so these days measure exposure risk, not what you breathed. We count only medium and heavy plumes.
Reading the AQI
EPA's Air Quality Index runs from 0 to 500. Up to 50 is good and 51-100 is moderate. Above 100 the air is unhealthy for sensitive groups (children, older adults, and people with asthma or heart or lung disease), and above 150 it is unhealthy for everyone. We count a county's bad days as days above 100, averaged over 2021-2025.
The air you actually breathe
No agency measures indoor air city by city, so nobody can tell you your home's numbers except a monitor in your home. What research does show: Americans spend about 90% of their time indoors (EPA's National Human Activity Pattern Survey, 2001), EPA studies in the 1980s often found indoor levels of some chemical vapors two to five times outdoor levels, and during wildfire smoke the particles get inside unless windows stay shut and a filter runs.
Indoor vs. outdoor airSources: EPA AirData annual AQI by county, 2021-2025; NOAA Hazard Mapping System smoke polygons, 2021-2025.