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

under 1 bad air day a year

Fewer bad air days than most monitored US counties. Ranked 753 of 996 monitored counties, where 1 is worst.

What makes them bad: a mix of particles and ozone (43% particle days).

Which months to watch

Most bad days here fall in June and August and September and October and November and December. Averaged over 2016 to 2025.

What to buy, and what not to

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 record for Lafourche

In 2000 to 2009 this county averaged 18 bad days a year; in 2016 to 2025, under 1. The air has improved. The worst recent year was 2019, with 2 bad days on 360 monitored days.

Date	AQI	Main pollutant
2019-09-06	126	Ozone
2020-10-01	115	Ozone
2024-12-19	115	PM2.5
2022-06-13	109	PM2.5
2025-11-23	109	PM2.5

Most days, not the worst ones

Across 3,609 monitored days from 2016 to 2025, the air in Lafourche Parish rated Good on 64% of them, less often than the 72% typical of monitored counties, and Moderate on 36%. The median day sat at AQI 45; one day in ten went above 59.

The pollutant setting the AQI on an ordinary day here:

fine particles (PM2.5)63%2,284 days
ozone37%1,325 days

Lafourche Parish by year

Year	Days monitored	Good	Moderate	Over 100	Median AQI	Highest AQI
2025*	365	246	118	1	44	109
2024	362	197	164	1	48	115
2023	365	153	211	1	53	101
2022	351	238	112	1	43	109
2021	347	204	143	0	45	84
2020	366	212	153	1	48	115
2019	360	173	185	2	51	126
2018	362	280	82	0	39	90
2017	365	300	65	0	38	87
2016	366	306	60	0	39	93
2015	365	277	88	0	38	97
2014	363	268	94	1	41	105
2013	365	290	74	1	40	146
2012	359	251	104	4	41	133
2011	365	238	121	6	44	133
2010	364	212	144	8	46	129

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

Louisiana compared

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.