Bad Air Days in St. James Parish, Louisiana: under 1 a Year

under 1 bad air day a year

Rare: among the cleanest-air counties EPA monitors. Ranked 813 of 996 monitored counties, where 1 is worst.

What makes them bad: mostly ozone: summer smog (0% particle days).

Which months to watch

Most bad days here fall in June and August and May. Averaged over 2016 to 2025.

What actually helps here

Bad air days are rare here. A standard furnace filter is enough; no purifier needed for outdoor air.
On the odd bad day, check AirNow and keep windows shut.

The worst days on file

In 2000 to 2009 this county averaged 9 bad days a year; in 2016 to 2025, under 1. The air has improved. The worst recent year was 2024, with 3 bad days on 363 monitored days.

Date	AQI	Main pollutant
2023-08-27	115	Ozone
2023-06-09	108	Ozone
2024-06-13	108	Ozone
2024-05-15	105	Ozone
2024-08-08	101	Ozone

Most days, not the worst ones

Across 3,575 monitored days from 2016 to 2025, the air in St. James Parish rated Good on 95% of them, more often than the 72% typical of monitored counties, and Moderate on 5%. The median day sat at AQI 31; one day in ten went above 46.

The pollutant setting the AQI on an ordinary day here:

ozone100%3,575 days

Every recent year on file

Year	Days monitored	Good	Moderate	Over 100	Over 150	Median AQI	Highest AQI
2025*	359	337	22	0	0	33	84
2024	363	339	21	3	0	32	108
2023	351	314	35	2	0	33	115
2022	361	345	16	0	0	32	93
2021	330	326	4	0	0	28	58
2020	357	351	6	0	0	29	90
2019	359	344	15	0	0	29	97
2018	364	350	14	0	0	27	93
2017	365	349	16	0	0	31	80
2016	366	347	19	0	0	31	84
2015	345	325	18	2	0	31	115
2014	344	318	25	1	1	33	154
2013	357	335	22	0	0	32	100
2012	365	340	23	2	0	33	122
2011	363	310	45	8	0	36	136
2010	362	312	48	2	0	37	105

*2025 may be a partial year in EPA's file.

Nearby counties on file

How this is counted

A bad air day is a day the county's daily AQI from EPA AirData went above 100, the level where EPA tells children, older adults and people with asthma or heart disease to cut back outdoors. Monitors do not run every day, so yearly counts are scaled to 365 days. This is the record, not today's air: for that, check AirNow. More on the method in how the county numbers are made, on the AQI 100 line in what counts as a bad air day, and on why a purifier does not touch ozone in smoke vs ozone.