Burlington Air Quality in 2021
In 2021, Burlington's air quality (Burlington-South Burlington, VT area) had a median daily AQI of 40 (Good) across 365 monitored days. 1 day (0.3%) reached Unhealthy for Sensitive Groups or worse, 288 were Good, and the year's peak AQI was 129 (Unhealthy for Sensitive Groups). Fine particulate matter (PM2.5) set the daily AQI on 190 of those days. The cleanest month of 2021 was September (median AQI 32, 0 days above 100) and the worst was July (median 42, 1 day above 100, peak 129).
- Good: 78.9%
- Moderate: 20.8%
- Unhealthy for Sensitive Groups: 0.3%
- Unhealthy or worse: 0.0%
Reduce Indoor Ozone in Burlington
Today's main pollutant in Burlington is ground-level ozone (AQI 24). 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.
Recommended: Levoit Core 300 — True HEPA + activated carbon · CADR ~141 CFM · rooms up to 219 sq ft
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How was Burlington's air quality in 2021?
Good on a typical day: median AQI 40, with 1 day above AQI 100 out of 365 monitored — the 5th cleanest of 7 years on record for the area.
- ✓Peak AQI in 2021: 129 (Unhealthy for Sensitive Groups).
- ✓Fine particulate matter (PM2.5) was the main pollutant on 190 days.
- ✓Cleanest month: September; worst: July.
Frequently asked questions
What was the average AQI in Burlington in 2021?▾
EPA's Air Quality System puts Burlington's (Burlington-South Burlington, VT) median daily AQI for 2021 at 40, which is Good. 1 day were Unhealthy for Sensitive Groups or worse and the year's highest AQI was 129.
Which month had the worst air quality in Burlington in 2021?▾
The cleanest month of 2021 was September (median AQI 32, 0 days above 100) and the worst was July (median 42, 1 day above 100, peak 129).
Was 2021 a good or bad year for Burlington's air?▾
Among the 7 years EPA has published for the area (2019–2025), 2021 ranks 5th cleanest by days above AQI 100. 2021's median of 40 is in line with the area's typical annual median of 39.
Burlington month by month in 2021
Burlington air quality month by month, 2021 (Burlington-South Burlington, VT, EPA AQS daily AQI)
| Month | Days monitored | Median AQI | Days above 100 | Peak AQI | Main pollutant |
|---|---|---|---|---|---|
| January | 31 | 41 | 0 | 83 | PM2.5 |
| February | 28 | 43 | 0 | 68 | O3 |
| March | 31 | 42 | 0 | 71 | O3 |
| April | 30 | 42 | 0 | 62 | O3 |
| May | 31 | 41 | 0 | 84 | O3 |
| June | 30 | 46 | 0 | 84 | O3 |
| Julyworst | 31 | 42 | 1 | 129 | PM2.5 |
| August | 31 | 47 | 0 | 82 | PM2.5 |
| Septembercleanest | 30 | 32 | 0 | 49 | O3 |
| October | 31 | 33 | 0 | 49 | PM2.5 |
| November | 30 | 35 | 0 | 67 | PM2.5 |
| December | 31 | 39 | 0 | 87 | PM2.5 |
How 2021 compares
Among the 7 years EPA has published for the area (2019–2025), 2021 ranks 5th cleanest by days above AQI 100.
2021's median of 40 is in line with the area's typical annual median of 39.
Activity-specific thresholds: running, cycling, kids' sports.
Right now in Burlington
The latest EPA AirNow observation puts Burlington's AQI at 24 (O3). The figures above are multi-year annual statistics, not today's reading.
View current Burlington air quality →Source: EPA Air Quality System (AQS) pre-generated Daily AQI by CBSA files — daily AQI by CBSA (Burlington-South Burlington, VT), 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.