Austin Air Quality in 2021
In 2021, Austin's air quality (Austin-Round Rock, TX area) had a median daily AQI of 51 (Moderate) across 365 monitored days. 1 day (0.3%) reached Unhealthy for Sensitive Groups or worse, 182 were Good, and the year's peak AQI was 101 (Unhealthy for Sensitive Groups). Fine particulate matter (PM2.5) set the daily AQI on 248 of those days. The cleanest month of 2021 was November (median AQI 39, 0 days above 100) and the worst was October (median 45, 1 day above 100, peak 101).
- Good: 49.9%
- Moderate: 49.9%
- Unhealthy for Sensitive Groups: 0.3%
- Unhealthy or worse: 0.0%
Reduce Indoor Ozone in Austin
Today's main pollutant in Austin is ground-level ozone (AQI 17). Important: standard HEPA filters do NOT remove ozone — only a purifier with a substantial activated-carbon bed adsorbs it. The biggest wins are cutting indoor sources (gas appliances, certain "ionizer" purifiers) and ventilating when outdoor ozone is low (early morning). A high-carbon unit helps with the gases and VOCs that linger indoors.
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How was Austin's air quality in 2021?
Moderate on a typical day: median AQI 51, with 1 day above AQI 100 out of 365 monitored — the 2nd cleanest of 7 years on record for the area.
- ✓Peak AQI in 2021: 101 (Unhealthy for Sensitive Groups).
- ✓Fine particulate matter (PM2.5) was the main pollutant on 248 days.
- ✓Cleanest month: November; worst: October.
Frequently asked questions
What was the average AQI in Austin in 2021?▾
EPA's Air Quality System puts Austin's (Austin-Round Rock, TX) median daily AQI for 2021 at 51, which is Moderate. 1 day were Unhealthy for Sensitive Groups or worse and the year's highest AQI was 101.
Which month had the worst air quality in Austin in 2021?▾
The cleanest month of 2021 was November (median AQI 39, 0 days above 100) and the worst was October (median 45, 1 day above 100, peak 101).
Was 2021 a good or bad year for Austin's air?▾
Among the 7 years EPA has published for the area (2019–2025), 2021 ranks 2nd cleanest by days above AQI 100. 2021's median of 51 is in line with the area's typical annual median of 52.
Austin month by month in 2021
Austin air quality month by month, 2021 (Austin-Round Rock, TX, EPA AQS daily AQI)
| Month | Days monitored | Median AQI | Days above 100 | Peak AQI | Main pollutant |
|---|---|---|---|---|---|
| January | 31 | 51 | 0 | 80 | PM2.5 |
| February | 28 | 50 | 0 | 68 | PM2.5 |
| March | 31 | 50 | 0 | 81 | PM2.5 |
| April | 30 | 54 | 0 | 88 | PM2.5 |
| May | 31 | 49 | 0 | 74 | O3 |
| June | 30 | 51 | 0 | 84 | PM2.5 |
| July | 31 | 53 | 0 | 79 | PM2.5 |
| August | 31 | 54 | 0 | 66 | PM2.5 |
| September | 30 | 61 | 0 | 90 | O3 |
| Octoberworst | 31 | 45 | 1 | 101 | PM2.5 |
| Novembercleanest | 30 | 39 | 0 | 53 | PM2.5 |
| December | 31 | 53 | 0 | 81 | PM2.5 |
How 2021 compares
Among the 7 years EPA has published for the area (2019–2025), 2021 ranks 2nd cleanest by days above AQI 100.
2021's median of 51 is in line with the area's typical annual median of 52.
Activity-specific thresholds: running, cycling, kids' sports.
Right now in Austin
The latest EPA AirNow observation puts Austin's AQI at 17 (O3). The figures above are multi-year annual statistics, not today's reading.
View current Austin air quality →Source: EPA Air Quality System (AQS) pre-generated Daily AQI by CBSA files — daily AQI by CBSA (Austin-Round Rock, TX), 2019–2025. Daily AQI per CBSA is the highest AQI reported by any monitor in the area that day; the defining parameter is the pollutant that set it. Month and season statistics pool every such day in the period across all years listed. Retrieved 2026-09-09.