Bad Air Days in Loudon County, Tennessee: 1 a Year

1 bad air day a year

Fewer bad air days than most monitored US counties. Ranked 650 of 996 monitored counties, where 1 is worst.

What makes them bad: mostly ozone: summer smog (27% particle days).

When the bad days come in Loudon

Most bad days here fall in April and June and November. 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.

Better or worse than it was

In 2000 to 2009 this county averaged 32 bad days a year; in 2016 to 2025, 1. The air has improved. The worst recent year was 2016, with 9 bad days on 280 monitored days.

Date	AQI	Main pollutant
2016-11-14	169	PM2.5
2016-11-08	159	PM2.5
2016-06-10	143	Ozone
2018-06-07	133	Ozone
2016-04-20	115	Ozone

Most days, not the worst ones

Across 3,514 monitored days from 2016 to 2025, the air in Loudon County rated Good on 76% of them, more often than the 72% typical of monitored counties, and Moderate on 24%. The median day sat at AQI 41; one day in ten went above 58.

The pollutant setting the AQI on an ordinary day here:

fine particles (PM2.5)56%1,972 days
ozone44%1,542 days

Loudon County by year

Year	Days monitored	Good	Moderate	Over 100	Over 150	Median AQI	Highest AQI
2025*	365	312	53	0	0	39	100
2024	366	286	80	0	0	42	100
2023	361	264	96	1	0	42	107
2022	365	303	62	0	0	39	77
2021	365	259	106	0	0	42	90
2020	366	299	67	0	0	38	97
2019	365	251	114	0	0	43	93
2018	365	273	91	1	0	39	133
2017	316	258	58	0	0	41	87
2016	280	170	101	9	2	47	169
2015	276	185	91	0	0	43	100
2014	278	184	92	2	0	44	101
2013	281	209	72	0	0	43	80
2012	243	171	59	13	2	44	177
2011	245	164	70	11	0	45	147
2010	237	157	72	8	0	45	133

*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.