Bad Air Days in Rockwall County, Texas: 1 a Year

1 bad air day a year

Fewer bad air days than most monitored US counties. Ranked 598 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 May and August and April and June and September. 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.

The record for Rockwall

In 2000 to 2009 this county averaged 19 bad days a year; in 2016 to 2025, 1. The air has improved. The worst recent year was 2018, with 5 bad days on 304 monitored days.

Date	AQI	Main pollutant
2018-05-06	136	Ozone
2020-08-17	133	Ozone
2018-04-28	129	Ozone
2018-06-21	126	Ozone
2024-08-08	126	Ozone

Most days, not the worst ones

Across 3,346 monitored days from 2016 to 2025, the air in Rockwall County rated Good on 94% of them, more often than the 72% typical of monitored counties, and Moderate on 6%. The median day sat at AQI 33; one day in ten went above 47.

The pollutant setting the AQI on an ordinary day here:

ozone100%3,346 days

Rockwall County by year

Year	Days monitored	Good	Moderate	Over 100	Over 150	Median AQI	Highest AQI
2025*	285	276	7	2	0	31	108
2024	340	315	23	2	0	34	126
2023	342	320	22	0	0	34	100
2022	360	339	21	0	0	34	100
2021	360	343	17	0	0	31	87
2020	363	345	17	1	0	32	133
2019	323	305	16	2	0	34	105
2018	304	281	18	5	0	31	136
2017	309	285	23	1	0	35	105
2016	360	331	29	0	0	35	77
2015	364	309	48	7	0	36	140
2014	360	314	45	1	0	36	105
2013	361	300	52	9	0	39	119
2012	365	289	64	12	2	39	204
2011	361	272	72	17	1	40	164
2010	363	305	53	5	0	37	150

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

Texas compared

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.