Many homes could have radon problems. Radon is an invisible radioactive gas that can cause cancer. Produced by decaying uranium, radon usually seeps from the ground into homes through basement cracks and other openings.

A recent U.S. Environmental Protection Agency report indicated that 63 percent of homes in North Dakota contained elevated levels of radon, the worst showing among the 17 states the agency tested.For peace of mind, Midwest Living magazine suggests homeowners have their homes tested.

"You don't know what you'll find or where until you test," advises Richard Welke, an environmental specialist with the Iowa Public Health Department.

Radon tests are easy to perform and inexpensive, usually $10 to $50. A charcoal canister detector is placed in a basement for several days and then analyzed in a laboratory.

Choose a testing service carefully, however. Reports abound of charlatans who pretend to measure radon with everything from candles to peanut-butter jars.

A high radon reading means homeowners probably should have a more precise testing done by a company with proven expertise. Solutions could be as simple as sealing basement cracks or as complex as installing underground ventilation.