Bad Air Days in Lafayette Parish, Louisiana: under 1 a Year

under 1 bad air day a year

Fewer bad air days than most monitored US counties. Ranked 759 of 996 monitored counties, where 1 is worst.

What makes them bad: mostly ozone: summer smog (29% particle days).

When the bad days come in Lafayette

Most bad days here fall in June and September and January and April and October. Averaged over 2016 to 2025.

Is a purifier worth it 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 14 bad days a year; in 2016 to 2025, under 1. The air has improved. The worst recent year was 2022, with 2 bad days on 364 monitored days.

Date	AQI	Main pollutant
2020-01-01	120	PM2.5
2023-09-01	112	Ozone
2024-06-14	108	Ozone
2024-10-12	108	Ozone
2017-09-14	105	Ozone

The air on a normal day

Across 3,646 monitored days from 2016 to 2025, the air in Lafayette Parish rated Good on 60% of them, less often than the 72% typical of monitored counties, and Moderate on 40%. The median day sat at AQI 46; one day in ten went above 63.

The pollutant setting the AQI on an ordinary day here:

fine particles (PM2.5)60%2,198 days
ozone40%1,443 days

Year by year

Year	Days monitored	Good	Moderate	Over 100	Median AQI	Highest AQI
2025*	362	238	124	0	45	79
2024	365	180	183	2	51	108
2023	365	211	153	1	47	112
2022	364	213	149	2	47	103
2021	365	243	122	0	42	87
2020	364	203	160	1	45	120
2019	365	212	153	0	46	84
2018	365	210	155	0	47	97
2017	365	218	146	1	45	105
2016	366	244	122	0	44	90
2015	365	167	198	0	52	97
2014	364	123	241	0	54	97
2013	365	140	223	2	53	119
2012	366	146	217	3	53	129
2011	365	126	234	5	54	133
2010	365	81	274	10	58	129

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

Elsewhere in Louisiana

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.