St. Louis City, Missouri Air Quality
St. Louis City 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 | 58 | 84 | 172 | 89 | 260 | 16 | PM2.5 |
| 2022 | 55 | 75 | 117 | 127 | 233 | 5 | PM2.5 |
| 2021 | 55 | 71 | 187 | 114 | 244 | 7 | PM2.5 |
| 2020 | 54 | 70 | 156 | 137 | 224 | 5 | PM2.5 |
| 2019 | 54 | 72 | 129 | 135 | 225 | 5 | PM2.5 |
| 2018 | 55 | 73 | 182 | 129 | 226 | 10 | PM2.5 |
| 2017 | 52 | 67 | 115 | 165 | 198 | 2 | PM2.5 |
| 2016 | 53 | 66 | 162 | 140 | 223 | 3 | PM2.5 |
| 2015 | 55 | 72 | 155 | 122 | 237 | 6 | PM2.5 |
| 2014 | 56 | 75 | 148 | 111 | 247 | 7 | PM2.5 |
What This Means for St. Louis City County Residents
St. Louis City, Missouri has received an Air Quality Grade of C (53/100) based on a decade of EPA monitoring data. The current median AQI of 58 falls in the "Moderate" range.
The primary pollutant affecting this area is Fine Particulate Matter (PM2.5). Over the past 5 years, this area has averaged 8 unhealthy air quality days per year — days when sensitive groups (children, elderly, those with respiratory conditions) should limit outdoor activity.