Radon is a gas produced by radium, a radioactive chemical element found in granite. The half-life of radon is a little over ninety-two hours. Only when radon levels in a home reach over 4 pCi/L (picocuries per liter) is there cause for concern.
The acronym NORM stands for "naturally occurring radioactive materials." All stone products including granite countertops contain certain levels of NORM capable of producing amounts of radiation.
The radon produced by a granite countertop is given off in such small, trace amounts that its effects on a person's health are negligible. Radon is thoroughly diluted by the air in a home.
According to the associates at Radon.com, more radon is given off by the soil beneath a home than is produced by the homeowner's granite countertop.
Some companies offer at-home radon detection kits capable of accurately detecting radon levels. These kits need to be used properly to provide accurate readings.