Last updated: 2026-05-23
Missouri Indoor Air Quality Guide
Missouri's karst geology creates underground radon pathways into basements
Zone 1 — Highest potential (predicted average > 4 pCi/L)
Radon Levels in Missouri
Average Radon Level
5.5 pCi/L
EPA Zone
Zone 1
Missouri is heavily Zone 1. The state's karst geology and limestone formations produce high radon. St. Louis and Kansas City suburbs routinely test above 4 pCi/L.
⚠️ Testing strongly recommended
Missouri is Zone 1 — the highest risk category. Test every home. If levels are 4 pCi/L or above, install a mitigation system immediately.
Top Indoor Air Hazards in Missouri
Radon Gas
CRITICALRadon is the #2 cause of lung cancer after smoking. It seeps from soil into basements and crawl spaces. You cannot see, smell, or taste it. The only way to know is to test.
Mold Exposure
HIGH RISKMold releases spores that trigger allergies, asthma attacks, and respiratory infections. Black mold (Stachybotrys chartarum) produces mycotoxins linked to neurological symptoms.
Lead Paint Dust
CRITICALLead paint was banned in 1978 but remains in millions of homes. Sanding, scraping, or peeling paint releases lead dust that causes irreversible brain damage in children. There is no safe level of lead exposure.
Missouri Climate & Air Quality Factors
Humid continental climate with hot summers and cold winters. St. Louis's brick housing stock traps moisture. Springfield area has unique cave-related radon pathways. Older housing has lead paint concerns.
Recommended Products for Missouri Homes
First Alert Radon Gas Test Kit
EPA-listed short-term radon test. Lab fees included. Results in days.
Airthings Corentium Home Radon Detector
Continuous digital radon monitoring. No lab fees. Real-time readings.
RadonAway RP140 Radon Mitigation Fan
Professional-grade radon mitigation fan. 4-inch. The core component of any radon reduction system. Cuts radon levels by up to 99%.
Mold Armor DIY Mold Test Kit
Test air quality and surfaces for mold. Results in 48 hours.
Disclaimer
State-level radon data from EPA Zone Map. Individual home levels vary significantly. This guide is for educational purposes and not a substitute for professional environmental testing. Test your home regardless of zone designation.
Guidance sourced from EPA, CDC, and Health Canada publications.