Bad Air Days in Jefferson County, Alabama: 7 a Year

7 bad air days a year

More bad air days than three quarters of monitored counties. Ranked 156 of 996 monitored counties, where 1 is worst.

What makes them bad: mostly ozone: summer smog (39% particle days).

When the bad days come in Jefferson

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

Is a purifier worth it here?

Ozone drives many bad days here. Purifiers and filters do not remove ozone, so do not buy one for that. Ozone peaks on hot afternoons: exercise outside in the morning.

Better or worse than it was

In 2000 to 2009 this county averaged 58 bad days a year; in 2016 to 2025, 7. The air has improved. The worst recent year was 2023, with 20 bad days on 365 monitored days.

Date	AQI	Main pollutant
2023-07-29	255	PM2.5
2023-07-30	255	PM2.5
2021-08-11	189	PM2.5
2023-06-29	178	PM2.5
2021-08-12	173	PM2.5

The air on a normal day

Across 3,653 monitored days from 2016 to 2025, the air in Jefferson County rated Good on 29% of them, less often than the 72% typical of monitored counties, and Moderate on 69%. The median day sat at AQI 56; one day in ten went above 76.

The pollutant setting the AQI on an ordinary day here:

fine particles (PM2.5)82%2,985 days
ozone18%653 days

Year by year

Year	Days monitored	Good	Moderate	Over 100	Over 150	Median AQI	Highest AQI
2025*	365	159	204	2	0	52	117
2024	366	95	265	6	0	57	119
2023	365	73	272	20	5	61	255
2022	365	128	235	2	0	54	105
2021	365	104	256	5	2	56	189
2020	366	119	244	3	0	54	129
2019	365	85	267	13	0	58	150
2018	365	98	263	4	1	56	156
2017	365	104	258	3	0	56	129
2016	366	105	252	9	1	56	151
2015	365	106	254	5	0	55	147
2014	365	69	290	6	0	58	112
2013	365	95	268	2	0	56	129
2012	366	70	276	20	4	58	172
2011	365	64	263	38	6	61	182
2010	365	55	280	30	4	63	166

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

Nearby counties on file

Shelby County2/yr
Etowah Countyunder 1/yr
Montgomery Countyunder 1/yr
Mobile Countyunder 1/yr
Madison Countyunder 1/yr
Morgan Countyunder 1/yr
Tuscaloosa Countyunder 1/yr
Lawrence Countythin data

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.