Saint Charles, Missouri Air Quality
Saint Charles County, Missouri (MO)
→ Stableover 10 years
10-Year AQI Trend
The solid line shows the median AQI each year. The dashed line shows the 90th percentile (worst 10% of days).
Air Quality Day Breakdown
Number of days per year in each EPA AQI category. Green = Good (AQI 0-50), Yellow = Moderate (51-100), Orange = Unhealthy for Sensitive Groups (101-150), Red = Unhealthy or worse (151+).
Year-by-Year Data
| Year | Median AQI | 90th Pct | Max AQI | Good Days | Moderate | Unhealthy+ | Pollutant |
|---|---|---|---|---|---|---|---|
| 2023 | 45 | 87 | 147 | 156 | 74 | 15 | Ozone |
| 2022 | 42 | 64 | 129 | 206 | 32 | 7 | Ozone |
| 2021 | 41 | 54 | 119 | 209 | 34 | 2 | Ozone |
| 2020 | 39 | 54 | 112 | 216 | 25 | 4 | Ozone |
| 2019 | 42 | 58 | 151 | 202 | 38 | 4 | Ozone |
| 2018 | 42 | 71 | 147 | 190 | 47 | 8 | Ozone |
| 2017 | 44 | 71 | 159 | 185 | 56 | 4 | Ozone |
| 2016 | 44 | 77 | 151 | 154 | 48 | 12 | Ozone |
| 2015 | 42 | 74 | 126 | 174 | 37 | 3 | Ozone |
| 2014 | 43 | 84 | 126 | 166 | 40 | 8 | Ozone |
What This Means for Saint Charles County Residents
Saint Charles, Missouri has received an Air Quality Grade of C (63/100) based on a decade of monitoring data from the EPA's air quality monitoring program. The current median AQI of 45 falls in the "Good" range.
The primary pollutant affecting this area is Ground-Level Ozone. Over the past 5 years, this area has averaged 6 unhealthy air quality days per year — days when sensitive groups (children, elderly, those with respiratory conditions) should limit outdoor activity. The American Lung Association's State of the Air report provides additional context on long-term health risks from air pollution exposure.
Related Cities in Missouri
Frequently Asked Questions
Saint Charles, Missouri has a current median AQI of 45, which falls in the "Good" range. The area has received an Air Quality Grade of C (63/100) based on 10 years of EPA monitoring data.
Air quality in Saint Charles, Missouri is stable over the past decade. The median AQI has changed by +2 points from 2014 to 2023.
Saint Charles, Missouri averages 6 unhealthy air quality days per year over the past 5 years. On these days, sensitive groups including children, the elderly, and those with respiratory conditions should limit outdoor activity.
The primary pollutant affecting Saint Charles, Missouri is Ground-Level Ozone. This is the dominant contributor to elevated AQI readings in the Saint Charles County area.
Saint Charles, Missouri averages 6 unhealthy air days per year. Asthma patients should monitor daily AQI readings and limit outdoor activity when AQI exceeds 100. The primary pollutant is Ground-Level Ozone, which is a known asthma trigger.
With a median AQI of 45 (Good), outdoor exercise in Saint Charles, Missouri is generally safe year-round. Saint Charles, Missouri averages 6 days per year when athletes should move workouts indoors.