Radon is a radioactive gas that is naturally found in the environment. It comes from the natural decay of uranium and thorium, which are two types of radioactive elements. Radon can enter your home through cracks in the foundation, through openings around pipes and wires, and through ventilation systems. The only way to know if there is too much radon in your home is to have it tested. There are many labs across the country that offer radon testing services. Your state or local health department may also provide information on where to get a test done.

Since you asked, I'll assume you're not a professional and give some general advice. Radon gas can be detected with special equipment, most commonly called a "radon detector" or "radon meter". There are a few different types of detectors available on the market, but all work based on the principle of alpha particle detection. The easiest way to test for radon is to hire a professional home inspector or environmental consultant who specializes in radon testing. These professionals have access to the proper equipment and know how to conduct the test properly.