Westminster, Ohio Air Quality
Westminster has a median AQI of 43, earning an air quality grade of A- — excellent air quality that ranks better than 39% of US cities. Air quality has been trending worse over the past decade, a concern for local residents and health officials. Particulate matter (PM2.5) is the primary concern, often linked to vehicle traffic, industrial activity, and wildfire smoke. In 2025, Westminster recorded 195 good air quality days (66% of monitored days) and 1 unhealthy days.
Population: 526 • County: Allen
Current AQI
Quick Facts
| Current AQI | 34 — Good |
| Air Quality Grade | A- |
| Median AQI (2025) | 43 |
| vs. U.S. Cities | Better than 39% |
| Primary Pollutant | PM2.5 |
| Unhealthy Days/Year | 1 |
| 10-Year Trend | ↓ Worsening |
| 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 Westminster is sourced from the Lima monitoring area, located approximately 6 miles from city center. This EPA-certified station continuously tracks particulate matter (PM2.5), the primary driver of air quality alerts in this area.
Westminster has relatively consistent air quality throughout the year without a strong seasonal peak. Air quality is primarily influenced by local traffic, industrial activity, and regional weather patterns rather than a single seasonal driver.
AQI Trend (10 Years)
Air Quality Days by Year
Westminster Median AQI by Year
Annual EPA air quality data for Westminster — median AQI, day-category breakdown, and primary pollutant per year.
| Year | Median AQI | Good Days | Unhealthy Days | Max AQI | Primary Pollutant |
|---|---|---|---|---|---|
| 2025 | 43 | 195 | 1 | 129 | PM2.5 |
| 2024 | 42 | 275 | — | 97 | Ozone |
| 2023 | 44 | 252 | 8 | 194 | PM2.5 |
| 2022 | 41 | 272 | — | 97 | Ozone |
| 2021 | 42 | 260 | — | 87 | PM2.5 |
| 2020 | 40 | 289 | 1 | 105 | Ozone |
| 2019 | 44 | 229 | — | 97 | Ozone |
| 2018 | 42 | 260 | 5 | 119 | Ozone |
| 2017 | 38 | 298 | 1 | 112 | Ozone |
| 2016 | 37 | 297 | 3 | 122 | Ozone |
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 Westminster Air Quality
What is the air quality in Westminster today?
The current AQI in Westminster is 34, 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 Westminster getting better or worse?
Air quality in Westminster has been worsening. The median AQI has risen 6 points (from 37 in 2016 to 43 in 2025), a concern for local health officials.
What is the most common air pollutant in Westminster?
PM2.5 is the primary air pollutant in Westminster, responsible for 149 days (50% of monitored days) in 2025. Particulate matter originates from vehicle exhaust, wildfires, construction, and industrial activity.
How many unhealthy air days does Westminster have per year?
In 2025, Westminster recorded 66% good air quality days (195 days) out of 296 monitored days. There were 1 Unhealthy for Sensitive Groups days and 0 Unhealthy days (AQI above 100). The highest single-day AQI recorded was 129.
What air quality grade does Westminster receive?
Westminster receives an air quality grade of A-, placing it better than 39% of US cities. This is based on a median AQI of 43 in 2025, with 195 good air quality days. The EPA monitors air quality in this area continuously using certified monitoring stations.
Air Quality Grade
Better than 39% of US cities
Nearby Cities
Get AQI Alerts
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National Rankings
See how Westminster compares to every other US city by air quality.
Best Air Quality Cities →All city rankingsRecommended Air Purifiers for Westminster
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