St. Louis Air Quality 2021: Historical AQI Data
Explore 2021 air quality data for St. Louis, including average AQI levels, seasonal patterns, pollution trends, and how air quality has changed over the year.
Current Air Quality
Air quality is acceptable. However, there may be a risk for some people, particularly those who are unusually sensitive to air pollution.
Historical Data
Historical air quality data for St. Louis in 2021 shows how pollution levels have changed over time. Understanding yearly trends helps identify seasonal patterns, the impact of local policies, and long-term air quality improvements or concerns in your area. Check current conditions below for today's AQI reading.
View Current Air Quality →PM2.5 Levels
Fine particulate matter data →
Ozone Levels
Ground-level ozone data →
Seasonal Guides
Air quality by season →
Health Effects
Learn about air pollution impacts →
Frequently Asked Questions About St. Louis Air Quality
What is the current air quality in St. Louis?
The current Air Quality Index (AQI) in St. Louis, MO is 56, which is considered moderate.
Is it safe to exercise outdoors in St. Louis?
Generally yes. With an AQI of 56, outdoor exercise is acceptable for most people. Sensitive individuals should monitor symptoms.
When is the best time of year to visit St. Louis for good air quality?
Spring and early fall typically offer the best air quality in St. Louis. Summer months may have elevated ozone levels, while winter can see higher PM2.5 from temperature inversions.
What causes air pollution in St. Louis?
Air pollution in St. Louis can come from vehicle emissions, industrial activity, construction, wildfires, and weather patterns. Local geography and seasonal factors also play a significant role.