Ann Arbor Air Quality in Summer
Across 2019–2025, Ann Arbor's summer (June–August) air quality had a median AQI of 49 (Good) over 644 monitored days in the Ann Arbor, MI area. 3.7% of summer days (24 of 644) reached Unhealthy for Sensitive Groups or worse, and ground-level ozone set the daily AQI on 55.7% of days. The cleanest summer on record here was 2019 (median AQI 44, 0 days above 100) and the worst was 2023 (median 58, 11 days above 100, peak AQI 218).
- Good: 52.6%
- Moderate: 43.6%
- Unhealthy for Sensitive Groups: 2.8%
- Unhealthy or worse: 0.9%
Improve Indoor Air Quality
Even with good outdoor air in Ann Arbor, indoor PM2.5, dust and allergens build up. A True-HEPA purifier keeps a bedroom or office consistently clean.
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How is the air in Ann Arbor in summer?
Good on a typical day: median AQI 49 across 2019–2025, with 3.7% of summer days above AQI 100. Ground-level ozone is the main driver.
- ✓52.6% of summer days were Good (AQI 0–50), 43.6% Moderate (51–100).
- ✓24 days of 644 reached AQI 101+; the summer peak was 218.
- ✓Cleanest month: August; worst month: June.
Frequently asked questions
What is the air quality like in Ann Arbor in summer?▾
Across 2019–2025, the median daily AQI in Ann Arbor in summer was 49 (Good). 52.6% of days were Good, 43.6% Moderate, and 3.7% reached Unhealthy for Sensitive Groups or worse, based on 644 monitored days in EPA's Air Quality System.
Is summer a good time for outdoor exercise in Ann Arbor?▾
A typical summer day in Ann Arbor sits in the Good range (median AQI 49), so running, cycling and children's outdoor play are fine for everyone on most days; about 1 day in 27 of summer days (3.7%) reached AQI 101+ in 2019–2025.
Which pollutant causes Ann Arbor's summer air quality problems?▾
Ground-level ozone set the daily AQI on 55.7% of summer days in Ann Arbor. The highest summer AQI recorded in 2019–2025 was 218 (Very Unhealthy), in 2023.
Ann Arbor summer air quality, year by year
Ann Arbor summer air quality by year (Ann Arbor, MI, EPA AQS daily AQI)
| Year | Days monitored | Median AQI | Days above 100 | Peak AQI | Main pollutant |
|---|---|---|---|---|---|
| 2019cleanest | 92 | 44 | 0 | 87 | O3 |
| 2020 | 92 | 51 | 6 | 160 | O3 |
| 2021 | 92 | 52 | 0 | 100 | PM2.5 |
| 2022 | 92 | 46 | 1 | 101 | O3 |
| 2023worst | 92 | 58 | 11 | 218 | PM2.5 |
| 2024 | 92 | 46 | 0 | 80 | O3 |
| 2025 | 92 | 52 | 6 | 152 | O3 |
What summer air means in Ann Arbor
A typical summer day in Ann Arbor sits in the Good range (median AQI 49), so running, cycling and children's outdoor play are fine for everyone on most days; about 1 day in 27 of summer days (3.7%) reached AQI 101+ in 2019–2025.
Summer's median AQI of 49 is above Ann Arbor's whole-year median of 44, making it one of the area's dirtier periods. Nationally, the median Summer AQI across every EPA metro area (308,645 metro-days, 2019–2025) is 46, so Ann Arbor runs in line with the national Summer norm; 3.7% of its Summer days topped AQI 100 versus 3.6% nationally (about the same).
Within the season, August is the cleanest month (median AQI 44, 0.5% of days above 100) and June the worst (median 51, 8.6% above 100).
Activity-specific thresholds: running, cycling, kids' sports.
Right now in Ann Arbor
The latest EPA AirNow observation puts Ann Arbor's AQI at 29 (PM2.5). The figures above are multi-year season 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.