Bad Air Days in Anderson County, Tennessee: under 1 a Year

under 1 bad air day a year

Rare: among the cleanest-air counties EPA monitors. Ranked 779 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 April 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 31 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 234 monitored days.

Date	AQI	Main pollutant
2019-09-10	105	Ozone
2019-09-13	105	Ozone
2023-04-20	105	Ozone
2025-04-18	105	Ozone
2024-08-29	100	Ozone

The air on a normal day

Across 2,380 monitored days from 2016 to 2025, the air in Anderson County rated Good on 89% of them, more often than the 72% typical of monitored counties, and Moderate on 11%. The median day sat at AQI 40; one day in ten went above 54.

The pollutant setting the AQI on an ordinary day here:

ozone100%2,380 days

Every recent year on file

Year	Days monitored	Good	Moderate	Over 100	Over 150	Median AQI	Highest AQI
2025*	244	230	13	1	0	39	105
2024	243	221	22	0	0	41	100
2023	237	212	24	1	0	41	105
2022	245	228	17	0	0	39	80
2021	235	219	16	0	0	38	87
2020	245	238	7	0	0	35	64
2019	234	177	55	2	0	44	105
2018	229	196	33	0	0	40	90
2017	245	214	31	0	0	40	90
2016	223	185	38	0	0	43	93
2015	240	216	24	0	0	39	97
2014	233	210	23	0	0	38	87
2013	237	221	16	0	0	38	77
2012	194	136	54	4	1	44	161
2011	238	176	54	8	0	44	122
2010	244	168	69	7	0	44	126

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

Elsewhere in Tennessee

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.