Radon is a cancer-causing, radioactive gas. It is colorless, odorless, tasteless, and chemically inert.
Radon is formed by the natural radioactive decay of uranium in rock, soil, and water. Naturally existing, low levels of uranium occur widely in Earth's crust; it can be found in all 50 states. Once radon is produced, it moves up through the ground into the air and can also dissolve into ground and surface water.
Radon is estimated to cause thousands of deaths each year. That's because when you breathe air containing radon, you can get lung cancer. Surgeon General has warned that radon is the second leading cause of lung cancer in the United States today. Only smoking causes more lung cancer deaths.
Nearly one out of every 15 homes has a radon level EPA considers to be elevated 4 pCi/L or greater. The U.S. average radon-in-air level in single family homes is 1.3 pCi/L. Indoor radon levels are very important because of the percentage of time we spend indoors.
The only way to determine how much radon is in the area is to test for it. The EPA states that any radon exposure carries some risk; no level of radon exposure is always safe. However, EPA recommends homes be fixed if an occupant's long-term exposure will average 4 picocuries per liter (pCi/L) or higher.