Ann Arbor Air Quality in 2020
In 2020, Ann Arbor's air quality (Ann Arbor, MI area) had a median daily AQI of 43 (Good) across 366 monitored days. 6 days (1.6%) reached Unhealthy for Sensitive Groups or worse, 236 were Good, and the year's peak AQI was 160 (Unhealthy). Fine particulate matter (PM2.5) set the daily AQI on 216 of those days. The cleanest month of 2020 was October (median AQI 34, 0 days above 100) and the worst was June (median 51, 3 days above 100, peak 126).
- Good: 64.5%
- Moderate: 33.9%
- Unhealthy for Sensitive Groups: 1.4%
- Unhealthy or worse: 0.3%
Reduce Indoor Ozone in Ann Arbor
Today's main pollutant in Ann Arbor is ground-level ozone (AQI 19). 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 Ann Arbor's air quality in 2020?
Good on a typical day: median AQI 43, with 6 days above AQI 100 out of 366 monitored — the 5th cleanest of 7 years on record for the area.
- ✓Peak AQI in 2020: 160 (Unhealthy).
- ✓Fine particulate matter (PM2.5) was the main pollutant on 216 days.
- ✓Cleanest month: October; worst: June.
Frequently asked questions
What was the average AQI in Ann Arbor in 2020?▾
EPA's Air Quality System puts Ann Arbor's (Ann Arbor, MI) median daily AQI for 2020 at 43, which is Good. 6 days were Unhealthy for Sensitive Groups or worse and the year's highest AQI was 160.
Which month had the worst air quality in Ann Arbor in 2020?▾
The cleanest month of 2020 was October (median AQI 34, 0 days above 100) and the worst was June (median 51, 3 days above 100, peak 126).
Was 2020 a good or bad year for Ann Arbor's air?▾
Among the 7 years EPA has published for the area (2019–2025), 2020 ranks 5th cleanest by days above AQI 100. 2020's median of 43 is in line with the area's typical annual median of 44.
Ann Arbor month by month in 2020
Ann Arbor air quality month by month, 2020 (Ann Arbor, MI, EPA AQS daily AQI)
| Month | Days monitored | Median AQI | Days above 100 | Peak AQI | Main pollutant |
|---|---|---|---|---|---|
| January | 31 | 37 | 0 | 71 | PM2.5 |
| February | 29 | 42 | 0 | 68 | PM2.5 |
| March | 31 | 45 | 0 | 63 | PM2.5 |
| April | 30 | 44 | 0 | 64 | PM2.5 |
| May | 31 | 42 | 0 | 56 | O3 |
| Juneworst | 30 | 51 | 3 | 126 | O3 |
| July | 31 | 52 | 3 | 160 | O3 |
| August | 31 | 44 | 0 | 80 | PM2.5 |
| September | 30 | 43 | 0 | 61 | PM2.5 |
| Octobercleanest | 31 | 34 | 0 | 59 | PM2.5 |
| November | 30 | 45 | 0 | 98 | PM2.5 |
| December | 31 | 43 | 0 | 95 | PM2.5 |
How 2020 compares
Among the 7 years EPA has published for the area (2019–2025), 2020 ranks 5th cleanest by days above AQI 100.
2020's median of 43 is in line with the area's typical annual median of 44.
Activity-specific thresholds: running, cycling, kids' sports.
Right now in Ann Arbor
The latest EPA AirNow observation puts Ann Arbor's AQI at 19 (O3). The figures above are multi-year annual statistics, not today's reading.
View current Ann Arbor air quality →Source: EPA Air Quality System (AQS) pre-generated Daily AQI by CBSA files — daily AQI by CBSA (Ann Arbor, MI), 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.