Bad Air Days in Smith County, Texas: 2 a Year

2 bad air days a year

Fewer bad air days than most monitored US counties. Ranked 586 of 996 monitored counties, where 1 is worst.

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

When the bad days come in Smith

Most bad days here fall in June and July and August and March and April and May. 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.

Better or worse than it was

In 2000 to 2009 this county averaged 22 bad days a year; in 2016 to 2025, 2. The air has improved. The worst recent year was 2022, with 6 bad days on 363 monitored days.

Date	AQI	Main pollutant
2019-04-09	133	Ozone
2022-06-29	122	Ozone
2022-07-13	122	Ozone
2023-05-27	119	Ozone
2023-08-21	115	Ozone

The air on a normal day

Across 3,640 monitored days from 2016 to 2025, the air in Smith County rated Good on 89% of them, more often than the 72% typical of monitored counties, and Moderate on 10%. The median day sat at AQI 36; one day in ten went above 54.

The pollutant setting the AQI on an ordinary day here:

ozone98%3,574 days
nitrogen dioxide2%66 days

Every recent year on file

Year	Days monitored	Good	Moderate	Over 100	Median AQI	Highest AQI
2025*	365	330	35	0	35	93
2024	363	314	48	1	39	105
2023	364	296	64	4	38	119
2022	363	289	68	6	40	122
2021	361	333	28	0	35	100
2020	366	352	14	0	33	84
2019	364	326	37	1	36	133
2018	364	324	38	2	33	112
2017	364	336	28	0	37	90
2016	366	344	21	1	37	101
2015	365	319	45	1	33	108
2014	365	329	36	0	34	100
2013	357	306	47	4	38	126
2012	365	286	72	7	40	147
2011	363	268	76	19	42	150
2010	365	297	62	6	38	115

*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.