RICHMOND, Va. (WRIC) — As the second-highest leading cause of lung cancer, the American Lung Association is urging Virginians to test their home for radon after a study found 25% of homes tested across the Commonwealth had dangerously high levels of the gas.

Radon is a naturally occurring radioactive gas emitted from the ground. It can enter a home through cracks in floors, basement walls, foundations and other openings, the American Lung Association said.

According to the American Lung Association, radon is the leading cause of lung cancer in people who have never smoked.

All radon test kits require different lengths of time which they need to be left out for to obtain an accurate result. Make sure you’re carefully checking the instructions to avoid potentially hazardous, inaccurate results.

“Radon is responsible for an estimated 21,000 lung cancer deaths every year and is the leading cause of lung cancer in people who have never smoked,” Kevin Stewart, Director of Environmental Health for the Lung Association, said. “Since radon is odorless, tasteless and colorless, the only way to detect radon in your home is to test the air. This is why it is critical for everyone to test their home.”

You can measure the levels of radon in your home by buying a do-it-yourself kit online here. Both short-term and long-term measuring kits are available. You can also contact the Virginia radon program with the Virginia Department of Health to hire a certified radon-testing professional.