Byrnes Mill, Missouri Air Quality
Byrnes Mill has a median AQI of 40, earning an air quality grade of A — excellent air quality that ranks better than 60% 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, Byrnes Mill recorded 117 good air quality days (79% of monitored days).
Population: 3,189 • County: Jefferson
Current AQI
Quick Facts
| Current AQI | 18 — Good |
| Air Quality Grade | A |
| Median AQI (2025) | 40 |
| vs. U.S. Cities | Better than 60% |
| Primary Pollutant | PM2.5 |
| Unhealthy Days/Year | 0 |
| 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 Byrnes Mill is sourced from the Arnold West monitoring area, located approximately 10 miles from city center. This EPA-certified station continuously tracks particulate matter (PM2.5), the primary driver of air quality alerts in this area.
Byrnes Mill 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
Byrnes Mill Median AQI by Year
Annual EPA air quality data for Byrnes Mill — median AQI, day-category breakdown, and primary pollutant per year.
| Year | Median AQI | Good Days | Unhealthy Days | Max AQI | Primary Pollutant |
|---|---|---|---|---|---|
| 2025 | 40 | 117 | — | 77 | PM2.5 |
| 2024 | 40 | 292 | 1 | 105 | Ozone |
| 2023 | 44 | 225 | 16 | 185 | PM2.5 |
| 2022 | 44 | 236 | 3 | 108 | PM2.5 |
| 2021 | 44 | 244 | 5 | 164 | PM2.5 |
| 2020 | 43 | 250 | 2 | 141 | PM2.5 |
| 2019 | 42 | 252 | 2 | 105 | Ozone |
| 2018 | 42 | 255 | 6 | 119 | PM2.5 |
| 2017 | 42 | 231 | 1 | 102 | PM2.5 |
| 2016 | 46 | 219 | 2 | 108 | 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 Byrnes Mill Air Quality
What is the air quality in Byrnes Mill today?
The current AQI in Byrnes Mill is 18, 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 Byrnes Mill getting better or worse?
Air quality in Byrnes Mill has been improving. The median AQI has dropped 6 points (from 46 in 2016 to 40 in 2025), a positive trend for residents.
What is the most common air pollutant in Byrnes Mill?
PM2.5 is the primary air pollutant in Byrnes Mill, responsible for 89 days (60% of monitored days) in 2025. Particulate matter originates from vehicle exhaust, wildfires, construction, and industrial activity.
How many unhealthy air days does Byrnes Mill have per year?
In 2025, Byrnes Mill recorded 79% good air quality days (117 days) out of 148 monitored days. There were 0 Unhealthy for Sensitive Groups days and 0 Unhealthy days (AQI above 100). The highest single-day AQI recorded was 77.
What air quality grade does Byrnes Mill receive?
Byrnes Mill receives an air quality grade of A, placing it better than 60% of US cities. This is based on a median AQI of 40 in 2025, with 117 good air quality days. The EPA monitors air quality in this area continuously using certified monitoring stations.
Air Quality Grade
Better than 60% of US cities
Nearby Cities
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National Rankings
See how Byrnes Mill compares to every other US city by air quality.
Best Air Quality Cities →All city rankingsRecommended Air Purifiers for Byrnes Mill
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