Radon is a radioactive gas that comes naturally from soil and rocks. You can’t see, taste, or smell radon. Radon can build up inside your house and cause lung cancer if you breathe it in over many years. Any home can have a radon problem, no matter the foundation type. Testing your home is the only way to know if radon is a problem. Everyone should test their home for radon. Radon is known to cause cancer. While there are many sources of radiation, radon remains the largest source of exposure. Because we spend so much time indoors, radon in the home represents the biggest concern. The Massachusetts Department of Public Health (DPH) recommends all homes and schools be tested for radon.