St. Michael, Pennsylvania Air Quality
St. Michael has a median AQI of 37, earning an air quality grade of A — excellent air quality that ranks better than 74% of US cities. Air quality has been improving steadily over the past decade, a positive sign for residents. Particulate matter (PM2.5) is the primary concern, often linked to vehicle traffic, industrial activity, and wildfire smoke. In 2025, St. Michael recorded 209 good air quality days (78% of monitored days) and 1 unhealthy days.
Population: 431 • County: Cambria
Current AQI
Quick Facts
| Current AQI | 21 — Good |
| Air Quality Grade | A |
| Median AQI (2025) | 37 |
| vs. U.S. Cities | Better than 74% |
| Primary Pollutant | PM2.5 |
| Unhealthy Days/Year | 1 |
| 10-Year Trend | ↑ Improving |
| Data Source | EPA AQS (historical) · AirNow (live) |
Health Recommendation
Air quality is satisfactory, and air pollution poses little or no risk.
It's a great day to be active outside!
5-Day AQI Forecast
Last 90 Days
Current Pollutant Levels
Real-time data from EPA AirNow
Local Air Quality Context
Air quality data for St. Michael is sourced from the Johnstown monitoring area, located approximately 8 miles from city center. This EPA-certified station continuously tracks particulate matter (PM2.5), the primary driver of air quality alerts in this area.
St. Michael tends to see elevated PM2.5 readings during fall and winter months when temperature inversions trap pollutants near the surface. Wood burning, vehicle exhaust, and reduced wind speeds compound the effect. Residents with respiratory conditions should monitor forecasts closely between November and February.
AQI Trend (10 Years)
Air Quality Days by Year
St. Michael Median AQI by Year
Annual EPA air quality data for St. Michael — median AQI, day-category breakdown, and primary pollutant per year.
| Year | Median AQI | Good Days | Unhealthy Days | Max AQI | Primary Pollutant |
|---|---|---|---|---|---|
| 2025 | 37 | 209 | 1 | 115 | PM2.5 |
| 2024 | 42 | 269 | — | 87 | PM2.5 |
| 2023 | 46 | 213 | 3 | 201 | PM2.5 |
| 2022 | 52 | 171 | 1 | 119 | PM2.5 |
| 2021 | 51 | 169 | 1 | 130 | PM2.5 |
| 2020 | 44 | 228 | — | 90 | PM2.5 |
| 2019 | 45 | 229 | — | 89 | PM2.5 |
| 2018 | 44 | 230 | — | 93 | PM2.5 |
| 2017 | 55 | 121 | — | 92 | PM2.5 |
| 2016 | 46 | 211 | — | 97 | PM2.5 |
Source: EPA Air Quality System (AQS) annual summaries. "Unhealthy Days" includes Unhealthy for Sensitive Groups, Unhealthy, Very Unhealthy, and Hazardous categories.
2025 Air Quality Summary
Primary Pollutant Days (2025)
Days when each pollutant was the primary driver of AQI. Learn about pollutants →
Frequently Asked Questions About St. Michael Air Quality
What is the air quality in St. Michael today?
The current AQI in St. Michael is 21, rated "Good". Air quality is good — outdoor activity is safe for everyone today. Air quality is satisfactory, and air pollution poses little or no risk.
Is air quality in St. Michael getting better or worse?
Air quality in St. Michael has been improving. The median AQI has dropped 9 points (from 46 in 2016 to 37 in 2025), a positive trend for residents.
What is the most common air pollutant in St. Michael?
PM2.5 is the primary air pollutant in St. Michael, responsible for 107 days (40% of monitored days) in 2025. Particulate matter originates from vehicle exhaust, wildfires, construction, and industrial activity.
How many unhealthy air days does St. Michael have per year?
In 2025, St. Michael recorded 78% good air quality days (209 days) out of 269 monitored days. There were 1 Unhealthy for Sensitive Groups days and 0 Unhealthy days (AQI above 100). The highest single-day AQI recorded was 115.
What air quality grade does St. Michael receive?
St. Michael receives an air quality grade of A, placing it better than 74% of US cities. This is based on a median AQI of 37 in 2025, with 209 good air quality days. The EPA monitors air quality in this area continuously using certified monitoring stations.
Air Quality Grade
Better than 74% of US cities
Nearby Cities
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National Rankings
See how St. Michael compares to every other US city by air quality.
Best Air Quality Cities →All city rankingsRecommended Air Purifiers for St. Michael
St. Michael sees its worst PM2.5 during winter temperature inversions when particulates get trapped near ground level. A unit with True HEPA and an auto-mode sensor is most effective for responding to these spikes.
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