Excerpted from Florida Department of Health website:
Radon is a naturally occurring, odorless, colorless, tasteless, radioactive gas produced from the radioactive decay of radium, found in most soils and earthen construction materials. Radon is the second leading cause of lung cancer in the U.S. after smoking, and the leading cause of lung cancer among non-smokers. The U.S. Environmental Protection Agency estimates that radon is responsible for more than 21,000 lung cancer deaths per year (about one person every 25 minutes). Data collected by the department indicates that 1 in 5 Florida residences has radon levels above the EPA action level of 4 pico curies per liter (pCi/L). Elevated radon levels have been found in all types of Florida buildings, including manufactured homes, schools and high-rise condominiums.
In some areas of Florida, one out of two homes has excessive amounts of radon. Floridians are exposed to concentrated radon gas as it enters their building. The Florida Department of Health, in conjunction with the local county public health units, is working to support Floridians as they protect themselves from radiation exposure from radon.
Check out the Florida Department of Health video.