Boston, Massachusetts – A dangerous gas may already be building inside homes across eastern Massachusetts as cool spring nights keep windows shut, allowing radon—known as the “invisible killer”—to accumulate indoors within hours. The risk increases quickly when homes remain sealed during overnight temperature drops common this time of year.
According to the U.S. Environmental Protection Agency, radon is a radioactive gas that forms naturally in soil and enters homes through foundation cracks, sump pumps, and basement floors. Massachusetts is considered a moderate- to high-risk state, with thousands of homes testing above the EPA action level of 4 picocuries per liter.
In Boston and across Suffolk, Middlesex, and Essex counties, older homes with basements are especially vulnerable. Cities including Cambridge, Lowell, and Worcester often see elevated indoor readings during early spring as residents limit ventilation overnight. The Massachusetts Department of Public Health reports radon is the second leading cause of lung cancer in the U.S., linked to about 21,000 deaths annually.
Radon exposure produces no immediate symptoms, making testing critical. Short-term test kits can deliver results within 48 to 96 hours, and mitigation systems can reduce indoor levels by up to 99 percent when properly installed.
Residents are urged to test homes now as conditions through April continue to favor indoor buildup. Additional advisories may be issued as elevated levels persist into early summer.
