Radon in the Home

• Radon is a gas that is produced by the breakdown of uranium, a radioactive mineral. All natural building materials that contain some degree of rock or soil will contain radon. These amounts of radon, however, are virtually undetectable and do not pose a health threat. The amount of radon that is considered to be a potential threat when measured inside an adequately ventilated home is 4 pCi/L or picocuries per liter. Most often, when a home is found to have large, measurable amounts of radon in the air, the source is found to be the soil beneath the home, not materials used within the home.
  
  

Granite and Radon

• True granite, an igneous rock that is made primarily up of feldspar and quartz is actually rarely used in the home as a countertop. Instead, other natural stones bearing the name of "commercial granite," which contain feldspar and quartz in varying levels combined with silica and mica are used. These commercial granites contain varying amounts of radioactive materials, just like all natural substances. When found in nature, in the quarries they are taken from, they may exist in such quantities that the radioactive materials may be measurable. In slab form, in the home, most granite countertops only produce as much as one atom of radon per year, far below the 4 picocuries per liter threshold set by the EPA.
  
  

Breakdown of Granite

• In order to release harmful amounts of radon, a stone would both need to contain significant amounts of radioactive materials and decay at a rate that would transform these materials into radon in measurable amounts. Granite that is so brittle or fragile as to be decomposing at a fast-enough rate to produce harmful amounts of radon would also be too brittle and fragile to be used as a countertop. The fact that the stone is sound enough to be cut, polished, shaped and installed means that it cannot be decomposing fast enough to be a threat.
  
  

Minimizing Radon

• If you are concerned about radon in the home, a radon mitigation system can be installed, which will reduce the amount of measurable radon to below the 4 picocuries per liter threshold. A radon mitigation system works by ventilating the house at a rate that distributes the radon, while blocking its entrance from slab floors and other entry points. If you suspect your granite counter or another source of building material in your home of producing radon, a mitigation system can be installed for about the same price as a new counter installation.