Granite & Radon
Granite is a term for several different classifications of igneous stones. Igneous stones are formed by the solidification of cooled molten rock. Many of these stones contain small amounts uranium or other minerals that emit particles over time. Some of these particles can be released in the form of radon gas. This natural occurring gas comes from many different sources, including drinking water, the air we breathe and the soil we stand on. Radon gas can be dangerous in very high concentrations but the amount of radon gas released by a granite countertop in most circumstances is less than one percent of that already present in the household air from other sources. Studies have concluded that the amount of radon you are exposed to from granite countertops is significantly less than the levels found in outside air, sometimes almost 270,000 times less. Please see the links below for more information.

2008 Study of Radon Levels in Granite
Marble Institute of America – Granite & Radon
MIA - Truth about Granite video
Association of Radon Scientists and Technologists - Position Statement
Environmental Health & Engineering – Radon Info
Executive Summary – Assessing Exposure to Radon & Radiation from Granite Countertops