Bad Air Days in Ascension Parish, Louisiana: 2 a Year

2 bad air days a year

Fewer bad air days than most monitored US counties. Ranked 516 of 996 monitored counties, where 1 is worst.

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

The bad-air season here

Most bad days here fall in May and April and August and September. 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 16 bad days a year; in 2016 to 2025, 2. The air has improved. The worst recent year was 2016, with 4 bad days on 365 monitored days.

Date	AQI	Main pollutant
2021-08-07	159	Ozone
2023-06-09	154	Ozone
2024-07-12	151	Ozone
2018-05-09	122	Ozone
2017-09-14	119	Ozone

An ordinary day in Ascension

Across 3,623 monitored days from 2016 to 2025, the air in Ascension Parish rated Good on 92% of them, more often than the 72% typical of monitored counties, and Moderate on 8%. The median day sat at AQI 33; one day in ten went above 50.

The pollutant setting the AQI on an ordinary day here:

ozone97%3,532 days
nitrogen dioxide3%91 days

Every recent year on file

Year	Days monitored	Good	Moderate	Over 100	Over 150	Median AQI	Highest AQI
2025*	364	348	15	1	0	33	108
2024	360	331	26	3	1	33	151
2023	362	310	49	3	1	34	154
2022	364	336	28	0	0	32	90
2021	356	338	16	2	1	31	159
2020	364	350	14	0	0	31	100
2019	361	319	41	1	0	33	101
2018	364	325	36	3	0	31	122
2017	363	334	27	2	0	34	119
2016	365	337	24	4	0	36	112
2015	363	326	32	5	0	34	140
2014	364	328	34	2	1	34	156
2013	365	342	23	0	0	32	100
2012	359	309	46	4	0	37	122
2011	362	302	49	11	2	35	156
2010	365	305	48	12	0	36	143

*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.