January is National Radon Action Month, which means it’s time to take action and protect your family from this silent intruder. Radon is colorless, odorless and can build up at dangerous levels in your home—if not tested—and it happens to be the leading cause of lung cancer in nonsmokers. Long-term exposure causes thousands of deaths each year, so it’s wise to be aware of the risk level in your home.

“Radon is a concern here in Colorado because of our geology and the presence of naturally occurring uranium in rock and soil,” says Rich Mylott, public affairs specialist with the U.S. Environmental Protection Agency’s (EPA)? Region 8 office in Denver.? “As this uranium decays, it releases radon gas that can rise up through the ground and collect in buildings, with basements and lower floors being the most vulnerable to high levels.”

EPA’s radon action level is set at 4 picocuries per liter, and Mylott recommends that those who see test results near or higher than that level take the proper steps to alleviate the issue. “Much of Colorado is considered ‘Zone 1’ for radon, reflecting the highest probability of elevated levels,” he says. “And about half of the homes in Colorado have the potential for radon levels that exceed the EPA’s action level of 4 picocuries per liter.”

The best way to prevent any health risks associated with radon is to understand the basic steps you can take to protect your family from exposure. Affordable at-home test kits are available in most hardware stores or can be ordered online through a program run by Kansas State University—just make sure to use a test that’s labeled as certified by the National Radon Proficiency Program. If you decide to use an at-home test kit, Mylott stresses the importance of following the instructions to ensure an accurate result. “Proper placement generally entails placing the kit in a lower level living space away from exterior windows, doors, vents or other places where air movement might affect the measurement,” he says.

If you get a result that indicates levels of concern, Mylott advises that you follow up with a professional. “Since radon is a relatively common concern here in Colorado, there are a lot of contractors out there with experience in testing and mitigation, he explains. “If you know you have radon in your home, these professionals can recommend the most cost-effective ways to reduce levels and prevent exposure.”

For more information on radon in Colorado visit colorado.gov.