Milwaukee Air Quality in 2020
In 2020, Milwaukee's air quality (Milwaukee-Waukesha-West Allis, WI area) had a median daily AQI of 48 (Good) across 366 monitored days. 7 days (1.9%) reached Unhealthy for Sensitive Groups or worse, 192 were Good, and the year's peak AQI was 169 (Unhealthy). Fine particulate matter (PM2.5) set the daily AQI on 231 of those days. The cleanest month of 2020 was May (median AQI 41, 0 days above 100) and the worst was June (median 53, 4 days above 100, peak 169).
- Good: 52.5%
- Moderate: 45.6%
- Unhealthy for Sensitive Groups: 1.6%
- Unhealthy or worse: 0.3%
Reduce Indoor Ozone in Milwaukee
Today's main pollutant in Milwaukee is ground-level ozone (AQI 32). 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 Milwaukee's air quality in 2020?
Good on a typical day: median AQI 48, with 7 days above AQI 100 out of 366 monitored — the 3rd cleanest of 7 years on record for the area.
- ✓Peak AQI in 2020: 169 (Unhealthy).
- ✓Fine particulate matter (PM2.5) was the main pollutant on 231 days.
- ✓Cleanest month: May; worst: June.
Frequently asked questions
What was the average AQI in Milwaukee in 2020?▾
EPA's Air Quality System puts Milwaukee's (Milwaukee-Waukesha-West Allis, WI) median daily AQI for 2020 at 48, which is Good. 7 days were Unhealthy for Sensitive Groups or worse and the year's highest AQI was 169.
Which month had the worst air quality in Milwaukee in 2020?▾
The cleanest month of 2020 was May (median AQI 41, 0 days above 100) and the worst was June (median 53, 4 days above 100, peak 169).
Was 2020 a good or bad year for Milwaukee's air?▾
Among the 7 years EPA has published for the area (2019–2025), 2020 ranks 3rd cleanest by days above AQI 100. 2020's median of 48 is in line with the area's typical annual median of 49.
Milwaukee month by month in 2020
Milwaukee air quality month by month, 2020 (Milwaukee-Waukesha-West Allis, WI, EPA AQS daily AQI)
| Month | Days monitored | Median AQI | Days above 100 | Peak AQI | Main pollutant |
|---|---|---|---|---|---|
| January | 31 | 53 | 0 | 79 | PM2.5 |
| February | 29 | 45 | 0 | 66 | PM2.5 |
| March | 31 | 52 | 0 | 73 | PM2.5 |
| April | 30 | 50 | 0 | 70 | PM2.5 |
| Maycleanest | 31 | 41 | 0 | 74 | O3 |
| Juneworst | 30 | 53 | 4 | 169 | O3 |
| July | 31 | 45 | 3 | 140 | O3 |
| August | 31 | 48 | 0 | 90 | O3 |
| September | 30 | 41 | 0 | 80 | PM2.5 |
| October | 31 | 44 | 0 | 62 | PM2.5 |
| November | 30 | 53 | 0 | 72 | PM2.5 |
| December | 31 | 54 | 0 | 85 | PM2.5 |
How 2020 compares
Among the 7 years EPA has published for the area (2019–2025), 2020 ranks 3rd cleanest by days above AQI 100.
2020's median of 48 is in line with the area's typical annual median of 49.
Activity-specific thresholds: running, cycling, kids' sports.
Right now in Milwaukee
The latest EPA AirNow observation puts Milwaukee's AQI at 32 (O3). The figures above are multi-year annual statistics, not today's reading.
View current Milwaukee air quality →Source: EPA Air Quality System (AQS) pre-generated Daily AQI by CBSA files — daily AQI by CBSA (Milwaukee-Waukesha-West Allis, WI), 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.