Air quality in Louisiana
EPA monitors report from 22 of Louisiana’s 64 counties. That is the honest limit of this page: the other 42 are not measured, not clean. In 2025 the most affected monitored county was Calcasieu Parish, with 3 days above the moderate category.
22
Counties with monitors
42
Counties without
12
Days above moderate, 2025
Summed across monitored counties
10.3%
Adults with asthma
Population-weighted county estimate
County by county
Monitored Louisiana counties
GoodModerateUnhealthy for sensitive groupsUnhealthyVery unhealthyHazardous
| County | 90th %ile AQI | Above moderate | Max AQI | 2025 days by category |
|---|---|---|---|---|
| Calcasieu Parish | 61 | 3 | 108 | |
| West Baton Rouge Parish | 61 | 2 | 122 | |
| Ascension Parish | 47 | 1 | 108 | |
| Bossier Parish | 57 | 1 | 101 | |
| East Baton Rouge Parish | 63 | 1 | 115 | |
| Iberville Parish | 61 | 1 | 105 | |
| Jefferson Parish | 63 | 1 | 101 | |
| Lafourche Parish | 57 | 1 | 109 | |
| St. Tammany Parish | 58 | 1 | 105 | |
| Caddo Parish | 57 | 0 | 80 | |
| Lafayette Parish | 59 | 0 | 79 | |
| Livingston Parish | 59 | 0 | 90 | |
| Orleans Parish | 55 | 0 | 71 | |
| Ouachita Parish | 58 | 0 | 80 | |
| Pointe Coupee Parish | 48 | 0 | 93 | |
| Rapides Parish | 57 | 0 | 67 | |
| St. Bernard Parish | 58 | 0 | 93 | |
| St. James Parish | 48 | 0 | 84 | |
| St. John the Baptist Parish | 48 | 0 | 87 | |
| St. Martin Parish | 50 | 0 | 77 | |
| Tangipahoa Parish | 53 | 0 | 64 | |
| Terrebonne Parish | 58 | 0 | 66 |
EPA Air Quality System annual summaries by county, 2025. The 90th percentile AQI describes a day worse than nine out of ten, which is a steadier measure than the annual maximum a single wildfire can set.
Not measured
42 counties without a monitor
No EPA monitor reported from these counties, so there is no air quality record to publish. Their radon zone is known, and radon is measured in the building rather than the air outside it.
- Acadia Parish
- Allen Parish
- Assumption Parish
- Avoyelles Parish
- Beauregard Parish
- Bienville Parish
- Caldwell Parish
- Cameron Parish
- Catahoula Parish
- Claiborne Parish
- Concordia Parish
- De Soto Parish
- East Carroll Parish
- East Feliciana Parish
- Evangeline Parish
- Franklin Parish
- Grant Parish
- Iberia Parish
- Jackson Parish
- Jefferson Davis Parish
- LaSalle Parish
- Lincoln Parish
- Madison Parish
- Morehouse Parish
- Natchitoches Parish
- Plaquemines Parish
- Red River Parish
- Richland Parish
- Sabine Parish
- St. Charles Parish
- St. Helena Parish
- St. Landry Parish
- St. Mary Parish
- Tensas Parish
- Union Parish
- Vermilion Parish
- Vernon Parish
- Washington Parish
- Webster Parish
- West Carroll Parish
- West Feliciana Parish
- Winn Parish
Other states
Air quality elsewhere
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