Chicago, Illinois – A dangerous gas could already be building inside homes across the Midwest as cool spring nights keep windows closed, allowing radon—known as the “invisible killer”—to accumulate indoors within hours. The risk can increase rapidly overnight as fluctuating temperatures lead residents to seal homes against lingering cold.
According to the U.S. Environmental Protection Agency, radon is a radioactive gas that forms naturally in soil and seeps into homes through foundation cracks, basements, and crawl spaces. The Midwest—including Illinois, Michigan, Wisconsin, Minnesota, Indiana, Ohio, Iowa, and Missouri—is one of the highest radon-risk regions in the country, with many states reporting elevated levels above the EPA action threshold.
Across major cities like Chicago, Detroit, Minneapolis, Indianapolis, and St. Louis, homes with basements are especially vulnerable this time of year. The region’s glacial soil and widespread basement construction create ideal conditions for radon to enter and build indoors, particularly during overnight sealing of homes.
Health officials warn radon is the second leading cause of lung cancer in the United States, linked to about 21,000 deaths annually. The gas produces no smell or immediate symptoms, making testing the only reliable way to detect it.
Residents across the Midwest are urged to test homes now as conditions through April continue to trap indoor air. Free and low-cost test kits are widely available, and mitigation systems can significantly reduce indoor levels before risks increase into early summer.
