Bad Air Days in Bexar County, Texas: 11 a Year
11 bad air days a year
Among the worst tenth of monitored US counties. Ranked 78 of 996 monitored counties, where 1 is worst.
What makes them bad: mostly ozone: summer smog (22% particle days).
The bad-air season here
- J
- F
- M
- A
- M
- J
- J
- A
- S
- O
- N
- D
Most bad days here fall in September and May and October and August. Averaged over 2016 to 2025.
Is a purifier worth it here?
- Ozone drives many bad days here. Purifiers and filters do not remove ozone, so do not buy one for that. Ozone peaks on hot afternoons: exercise outside in the morning.
The worst days on file
In 2000 to 2009 this county averaged 22 bad days a year; in 2016 to 2025, 11. The air has improved. The worst recent year was 2024, with 22 bad days on 366 monitored days.
| Date | AQI | Main pollutant |
|---|---|---|
| 2023-01-01 | 309 | PM2.5 |
| 2022-12-31 | 214 | PM2.5 |
| 2017-01-01 | 203 | PM2.5 |
| 2024-01-01 | 199 | PM2.5 |
| 2019-01-01 | 175 | PM2.5 |
An ordinary day in Bexar
Across 3,651 monitored days from 2016 to 2025, the air in Bexar County rated Good on 42% of them, less often than the 72% typical of monitored counties, and Moderate on 55%. The median day sat at AQI 52; one day in ten went above 77.
The pollutant setting the AQI on an ordinary day here:
- fine particles (PM2.5)64%2,347 days
- ozone35%1,271 days
Every recent year on file
| Year | Days monitored | Good | Moderate | Over 100 | Over 150 | Median AQI | Highest AQI |
|---|---|---|---|---|---|---|---|
| 2025* | 365 | 158 | 196 | 11 | 1 | 52 | 154 |
| 2024 | 366 | 174 | 170 | 22 | 2 | 52 | 199 |
| 2023 | 365 | 164 | 189 | 12 | 2 | 52 | 309 |
| 2022 | 365 | 116 | 236 | 13 | 1 | 55 | 214 |
| 2021 | 365 | 113 | 240 | 12 | 0 | 55 | 147 |
| 2020 | 366 | 119 | 237 | 10 | 1 | 55 | 160 |
| 2019 | 365 | 117 | 243 | 5 | 1 | 55 | 175 |
| 2018 | 365 | 187 | 167 | 11 | 1 | 49 | 166 |
| 2017 | 363 | 186 | 171 | 6 | 2 | 50 | 203 |
| 2016 | 366 | 199 | 161 | 6 | 1 | 49 | 164 |
| 2015 | 365 | 139 | 212 | 14 | 3 | 53 | 156 |
| 2014 | 365 | 129 | 230 | 6 | 0 | 54 | 136 |
| 2013 | 365 | 149 | 199 | 17 | 2 | 53 | 154 |
| 2012 | 366 | 138 | 212 | 16 | 4 | 53 | 161 |
| 2011 | 365 | 141 | 202 | 22 | 2 | 53 | 154 |
| 2010 | 365 | 167 | 187 | 11 | 2 | 51 | 154 |
*2025 may be a partial year in EPA's file.
Nearby counties on file
- Harris County29/yr
- El Paso County26/yr
- Tarrant County19/yr
- Denton County17/yr
- Dallas County12/yr
- Collin County11/yr
- Cameron County9/yr
- Montgomery County8/yr
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.