Radon Pros in Missouri

Last updated: March 2026

Missouri has significant radon risk, with large portions of the state classified as EPA Zone 1 and Zone 2. Central and northern Missouri counties have the highest predicted indoor radon potential, driven by karst limestone geology and glacial soil deposits. The St. Louis and Kansas City metropolitan areas both include neighborhoods where homes consistently test above the EPA action level of 4.0 pCi/L. Missouri's karst topography — the same geology that produces the state's caves and springs — creates natural pathways for soil gases, including radon, to migrate toward the surface and into home foundations. Missouri does not require separate state mitigation licensing, relying on national NRPP and NRSB credentials as the professional standard. In real estate transactions, radon testing is not mandated but is increasingly common in the St. Louis and Kansas City markets. Missouri's radon profile is notable for the role of karst geology in amplifying risk — homes built over or near limestone formations and sinkholes can have elevated radon levels even in areas with moderate zone classification. The Missouri Department of Health and Senior Services recommends testing all homes regardless of location. Both of Missouri's major metropolitan areas have active radon awareness programs and sufficient contractor availability for mitigation work.