AIR QUALITY MO

Air Quality in Saint Louis, MO: Moderate (56 AQI)

AQI 56 · Moderate · PM2.5 · Updated 2026-05-03

Saint Louis's air quality is moderate. Unusually sensitive people should consider reducing prolonged outdoor exertion.

Data: EPA AirNow, FEMA National Risk Index Last verified: 2026-05-03

Average AQI

Moderate

AQI Category

Wildfire Risk

Mold Score

ZIP Codes

What is AQI?

The Air Quality Index (AQI) is a standardized scale from 0 to 500 that measures air pollution levels. 0-50 is "Good," 51-100 is "Moderate," 101-150 is "Unhealthy for Sensitive Groups," and above 150 is "Unhealthy" for everyone. AQI tracks five major pollutants: ground-level ozone, particulate matter (PM2.5 and PM10), carbon monoxide, sulfur dioxide, and nitrogen dioxide. Saint Louis's average AQI of 56 falls in the "Moderate" range.

Air Quality Map: Saint Louis, MO

Each dot represents a ZIP code. Color indicates AQI level. Tap a dot for details.

Good (0-50) Moderate (51-100) USG (101-150) Unhealthy (151+)

Air Quality by ZIP Code in Saint Louis

AQI varies across Saint Louis's 68 ZIP codes based on proximity to pollution sources and local geography.

ZIP Code	AQI	Category	Wildfire	Mold
63114	57	Moderate	12	62	View report →
63119	57	Moderate	13	62	View report →
63122	57	Moderate	13	59	View report →
63124	57	Moderate	13	59	View report →
63126	57	Moderate	13	56	View report →
63127	57	Moderate	13	55	View report →
63128	57	Moderate	13	57	View report →
63131	57	Moderate	13	55	View report →
63132	57	Moderate	12	62	View report →
63134	57	Moderate	7	56	View report →
63140	57	Moderate	7	47	View report →
63141	57	Moderate	12	52	View report →
63144	57	Moderate	13	64	View report →
63145	57	Moderate	13	35	View report →
63146	57	Moderate	12	52	View report →

Showing 15 of 20 ZIP codes. View all.

Air Quality Overview

Saint Louis, Missouri has moderate air quality with an average AQI of 56. Air quality is acceptable, though some pollutants may be a concern for a small number of people who are unusually sensitive to air pollution. The dominant pollutant is PM2.5.

The Air Quality Index (AQI) is an EPA-standardized scale from 0 to 500. Values below 50 are "Good," 51-100 "Moderate," 101-150 "Unhealthy for Sensitive Groups," 151-200 "Unhealthy," 201-300 "Very Unhealthy," and above 300 "Hazardous."

Dominant Pollutant: PM2.5

PM2.5 (fine particulate matter) consists of particles smaller than 2.5 micrometers — about 30 times thinner than a human hair. These particles can penetrate deep into the lungs and enter the bloodstream.

Health effects of PM2.5 exposure:

Short-term: coughing, shortness of breath, aggravated asthma
Long-term: reduced lung function, cardiovascular disease, premature death
Most vulnerable: children, elderly, people with heart or lung disease

Common sources in urban areas: vehicle exhaust, construction dust, industrial emissions, wildfire smoke, residential wood burning.

Air Quality by ZIP Code in Saint Louis

AQI varies across Saint Louis's 68 ZIP codes based on proximity to pollution sources, traffic patterns, and local geography:

ZIP Code	AQI	Category	Wildfire Risk	Mold Score
63114	57	Moderate	12	62
63119	57	Moderate	13	62
63122	57	Moderate	13	59
63124	57	Moderate	13	59
63126	57	Moderate	13	56
63127	57	Moderate	13	55
63128	57	Moderate	13	57
63131	57	Moderate	13	55
63132	57	Moderate	12	62
63134	57	Moderate	7	56
63140	57	Moderate	7	47
63141	57	Moderate	12	52
63144	57	Moderate	13	64
63145	57	Moderate	13	35
63146	57	Moderate	12	52

Showing 15 of 68 ZIP codes. Check your specific ZIP for detailed data.

Wildfire Smoke Risk

Saint Louis has a low wildfire smoke risk with an average smoke risk score of 9 (scale 0-100). However, smoke from distant wildfires can temporarily degrade air quality even in low-risk areas.

Metric	Value
Avg. smoke risk score	9
Max smoke risk score	14
Fires within 100 km	148
High-risk ZIP codes	0

Wildfire smoke contains PM2.5, carbon monoxide, and volatile organic compounds. Even short-term exposure can trigger asthma attacks and respiratory distress.

Indoor Mold Risk

Saint Louis has an average mold risk score of 49 out of 100, with 37 ZIP codes in the high-risk category.

Factor	Value
Mold risk score	49/100
Average humidity	68% RH
High-risk ZIPs	37
Peak season	summer high

Mold risk is influenced by humidity levels, housing age (older homes have more moisture issues), flood history, and water infrastructure quality. Indoor humidity above 60% creates favorable conditions for mold growth.

Signs of mold problems: musty odors, visible growth on walls or ceilings, worsening allergies indoors, condensation on windows. Professional mold testing ($300-$600) can identify hidden issues.

Health Recommendations

With moderate air quality (AQI 56), most people can be active outdoors. Sensitive groups should take precautions:

Sensitive groups (asthma, COPD, heart disease): consider reducing prolonged outdoor exertion
Keep windows closed on high-pollution days
Use a HEPA air purifier in main living areas
Check AirNow.gov before outdoor exercise

Saint Louis vs. Nearby Missouri Cities

How Saint Louis's air quality compares to nearby cities:

City	AQI	Category	Population
Saint Louis	56	Moderate	21,578
Cook Sta	N/A	N/A	20,800
Saint James	N/A	N/A	20,800
Vichy	N/A	N/A	20,800

ZIP Codes in Saint Louis

Saint Louis covers 68 ZIP codes. Air quality can vary by neighborhood based on proximity to highways, industrial areas, and green spaces. Check your specific ZIP code for localized data.

Data Sources

Air quality: EPA AirNow — real-time and historical AQI data
Wildfire risk: FEMA National Risk Index
Mold risk: Derived from EPA, FEMA, Census ACS (humidity, housing age, flood history)
Monthly AQI: EPA Air Quality Statistics

Updated daily.

Frequently Asked Questions

Is the air safe to breathe in Saint Louis?

Saint Louis's average AQI is 56 (Moderate). Air quality is acceptable, but unusually sensitive individuals may experience respiratory symptoms during peak pollution times.

How many unhealthy air days does Saint Louis have?

Saint Louis has zero recorded unhealthy air quality days, which is excellent. Air quality can still vary seasonally due to wildfire smoke, pollen, or industrial activity.

What is the AQI in Saint Louis?

The average Air Quality Index (AQI) in Saint Louis is 56, categorized as Moderate. The primary pollutant is PM2.5. AQI ranges from 0-500, where 0-50 is Good, 51-100 Moderate, 101-150 Unhealthy for Sensitive Groups, and 151+ Unhealthy.

What is the wildfire risk in Saint Louis?

Saint Louis has a wildfire risk score of 9 out of 100. Low wildfire risk means smoke events are uncommon, but regional fires can still temporarily affect air quality.

Is mold a concern in Saint Louis?

Saint Louis has a mold risk score of 49 out of 100, based on humidity, precipitation, and temperature data. Maintain good ventilation and address any water intrusion promptly to prevent mold growth.

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