Radon Pros in Wisconsin

Last updated: March 2026

Wisconsin is classified as a high-risk state for radon, with most of the southern and western regions solidly in EPA Zone 1. The Milwaukee and Madison metropolitan areas are both in high-risk zones, meaning the majority of Wisconsin's population lives in areas with elevated predicted indoor radon potential. Wisconsin's glacial geology — the same deposits that shaped the state's distinctive landscape — is the primary driver of radon gas generation. The combination of permeable glacial soils, uranium-bearing bedrock, and cold winters that create tight building envelopes produces consistently elevated readings. Wisconsin requires radon measurement professionals to be registered with the Wisconsin Department of Health Services, providing a regulatory framework for testing qualification. In real estate transactions, radon testing is not state-mandated but is standard practice in the Milwaukee metro, Madison area, and most southern Wisconsin markets. Wisconsin's radon profile is significant because of the overlap between Zone 1 classification and population density — the state's largest metro areas are also its highest-risk areas. The Wisconsin Department of Health Services maintains an active radon program and recommends testing every home in the state, with particular emphasis on homes with basements, which are the predominant foundation type throughout Wisconsin.