Bad Air Days in Shelby County, Alabama: 2 a Year

2 bad air days a year

Fewer bad air days than most monitored US counties. Ranked 584 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 September. 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 worst days on file

In 2000 to 2009 this county averaged 33 bad days a year; in 2016 to 2025, 2. The air has improved. The worst recent year was 2016, with 4 bad days on 244 monitored days.

Date	AQI	Main pollutant
2016-06-09	133	Ozone
2019-06-04	119	Ozone
2016-06-10	112	Ozone
2018-06-07	112	Ozone
2016-06-30	108	Ozone

Most days, not the worst ones

Across 2,422 monitored days from 2016 to 2025, the air in Shelby County rated Good on 90% of them, more often than the 72% typical of monitored counties, and Moderate on 10%. The median day sat at AQI 38; one day in ten went above 52.

The pollutant setting the AQI on an ordinary day here:

ozone100%2,422 days

Shelby County by year

Year	Days monitored	Good	Moderate	Over 100	Over 150	Median AQI	Highest AQI
2025*	243	222	21	0	0	36	87
2024	239	216	23	0	0	40	97
2023	242	207	34	1	0	40	108
2022	245	225	19	1	0	37	105
2021	243	231	12	0	0	35	77
2020	241	232	9	0	0	34	67
2019	244	202	39	3	0	42	119
2018	242	217	24	1	0	38	112
2017	239	222	17	0	0	38	97
2016	244	205	35	4	0	41	133
2015	257	207	48	2	0	40	115
2014	273	200	72	1	0	42	119
2013	285	206	78	1	0	42	101
2012	283	185	92	6	0	45	150
2011	282	165	104	13	1	47	166
2010	278	152	119	7	2	48	156

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

Nearby counties on file

Jefferson County7/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.