Radon Pros in Indiana

Last updated: March 2026

Indiana has one of the most widespread radon problems in the Midwest. According to EPA mapping, approximately two-thirds of Indiana's 92 counties are classified as Zone 1 — the highest predicted indoor radon potential. The highest concentrations are in central and northern regions, including the Indianapolis metropolitan area where Marion, Hamilton, Hendricks, and Johnson counties consistently report elevated readings. Indiana's glacial soil deposits, rich in uranium-bearing minerals, create ideal conditions for radon gas generation and soil-gas transport into home foundations. Indiana does not require state-specific radon licensing beyond national NRPP or NRSB certification, making credential verification especially important for homeowners. In real estate transactions, radon testing is not state-mandated but is considered standard practice in the central Indiana market. What makes Indiana's radon situation noteworthy is the combination of high risk coverage and relatively low public awareness compared to neighboring states like Ohio and Illinois. The Indiana State Department of Health actively promotes radon testing, noting that the state has the second-highest average radon levels in the Midwest behind Iowa. Every Indiana home should be tested, especially those with basements or crawlspace foundations in the central and northern counties.