Looking at the Environmental Protection Agency's map of radon zones in the U.S., the upper Great Plains states are mostly red, along with much of Indiana, Illinois, Ohio and the northeast.
A swath of red cuts a crescent shape through the heart of Kentucky.
But the map isn't an indication that every house in the red area has high levels of radon, a radioactive gas you can't smell, see or taste. High radon levels can be found in low-risk areas and vice versa. It is estimated one in 15 American homes have elevated levels of radon.
Radon is the nation's leading cause of lung cancer among nonsmokers, and, overall, it is the second leading cause of lung cancer, responsible for more than 20,000 deaths annually.
For smokers, high radon levels pack a double whammy. The U.S. National Library of Medicine reports smokers account for more than 85 percent of radon-induced lung cancer deaths.
"There is a high radon potential throughout Kentucky, and that is why all homes need to be tested," said Clay Hardwick, who works for the Department of Public Health and oversees the radon kit program. "Any home that has an average reading above 4 picocuries per liter, or pCi/L after two short-term (tests) is recommended to be mitigated."
But, Hardwick said, there is no known safe level for radon exposure. Federal officials have recommended for years that homeowners should consider fixing their homes if the level is between 2 and 4 pCi/L.
Since 1990, the Kentucky Department of Public Health has made available a free radon kit to households that request them. Last year, the department sent out about 6,000 kits, Hardwick said.
The EPA State Indoor Radon Grant funds the program, which receives between $250,000 and $300,000 annually.
Anyone interested in a free kit should contact 502-564-4856. Kits also are available at most home improvement stores, such as Lowe's and Home Depot.
The short-term kit sits in a home 48 hours before being mailed to a lab for analysis. The long-term kit remains in the home more than 90 days.
If the short-term test shows elevated levels, the homeowner is advised to take a second short-term test or go for the long-term one.
"More and more, homebuyers and renters are asking about radon levels before they buy or rent a home," the state's guide said.
He has sold real estate locally for 16 years. He remembers fewer than five people asking for a radon test before signing on the dotted line.
Homeowners who need mitigation efforts should contact a certified radon contractor about installing a system. The National Radon Proficiency Program -- www.nrpp.info -- shows nearly 40 service providers in Kentucky. Bowling Green and Elizabethtown contractors are the closest to Daviess County.