Granite Counter Tops
The question about the presence of radon in granite countertops is not new. In recent times the issue has received more exposure, due in part to media attention and the growth in granite's popularity as a countertop choice.
Any type of rock could contain naturally occurring radioactive elements like radium, uranium and thorium. Some pieces of granite may contain more of these elements than others.
If present, these radioactive elements will decay into radon which may be released from the granite over time. However, since granite is generally not very porous, less radon is likely to escape from it than from a more porous stone such as sandstone. It’s important to know that radon originating in the soil beneath homes is a more common problem and is a far larger public health risk than radon from granite building materials. Also, any radon from granite countertops in kitchens or bathrooms is likely to be diluted in the typical home since those rooms are usually well ventilated.
It is extremely unlikely that granite countertops in homes could increase the radiation dose above the normal natural background that comes from soil and rocks.