Introduction to Radon & Health Risk
The Fundamentals of Radon & Radioactivity
Radon Occurrence & Behavior
Radon Measurement & Devices
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Source #2 – Building Materials

Radon can emanate through the building materials from which it is constructed.  All natural products, especially stone, minerals, and sand, contain trace amounts of some radioactive elements called NORMs (Naturally Occurring Radioactive Mineral) that can produce measurable amounts of radiation and sometimes radon gas. Therefore, most building materials made from naturally formed rock have the potential of containing varying amounts of naturally occurring radiation.  NORMs such as uranium, radium, and thorium can be present in a wide number of minerals that appear as crystals in granite from around the world.  Therefore, it is not unusual for materials such as granite to have some amount of radioactivity. 

Depending on the composition of the molten rock from which they formed, some pieces of granite can exhibit more radioactivity than others.  In 2008, EPA restated its position on radon in granite counter tops: “EPA has not conducted studies on radioactivity in granite countertops. However, based on the limited information available, EPA believes that most types of granite used in countertops and other aspects of home construction are probably not major contributors of radiation and radon in the home. EPA will continue to monitor and analyze the evolving research on this issue and will update its recommendations if appropriate”.

Emanation
Something that issues from a source; an emission. Any of several radioactive gases that are isotopes of radon & are products of radioactive decay.  
Study Tip

Although natural stone building materials are likely to emit a small amount of radioactivity, it will generally be insignificant when diluted with the quantity of air in the entire home.  The risk for radon emanating from soil beneath the home is hundreds of times greater than the risk from granite. 

The EPA’s Consumer Guide to Radon Reduction states: “In a small number of homes, the building materials (e.g., granite and certain concrete products) can give off radon, although building materials rarely cause radon problems by themselves. In the United States, radon gas in soils is the  principal source of elevated radon levels in homes.”