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Granite and Radom Gas

Here is a summary of the study of radom gas in granite countertops from the MIA.

"Radon gas occurs naturally in the environment and is present in outdoor and

indoor air throughout the world. Radium, which is the source of radon gas, is a

natural and minor constituent of many common building materials such as

concrete, brick, gypsum, and natural stone. Granite and other stones that are a

popular choice for countertops and other decorative features in homes have been

evaluated extensively. Over 500 measurements of radon emissions from granite

have been published in the peer reviewed scientific literature. This information

provides a reasonable basis for preliminary estimates of typical and upper bound

levels of radon in indoor air of homes associated with emissions from natural

stone countertops.

The average and maximum radon concentrations estimated from these data to

result from emissions by natural stone are low in comparison to relevant

benchmarks of radon exposure. The radon concentration estimated as a result of

average radon emissions from natural stone reported in the scientific literature is

approximately:

300 times lower than (or 0.3% of) levels of radon in outdoor air,
1,000 times below (or 0.001% of) the average concentration of radon found in
the air of U.S. homes, and
3,000 times less than (or 0.00004% of) the action level for indoor air
recommended by the U.S. Environmental Protection Agency (EPA).

Further refined assessments of indoor exposure to radon as a result of emissions

from natural stone will be possible as additional information becomes available

about other types of stones in the marketplace, including their various

applications in homes and radon emission rates. Nonetheless, information 2

available at present indicates that radon levels associated with natural stone

countertops in homes are low in comparison to background levels of exposure and

natural stone is a minor contributor compared to other sources of radon gas.


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