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Position Statement
Granite Countertops and Radon
Gas
From the Technical and Science Committee
of the American
Association of Radon Scientists and Technologists (AARST)
Radon Risk
The primary concern about indoor
radon gas is the increased risk of lung cancer that exists from breathing radon
and its byproducts. The magnitude of the risk depends on the radon concentration
in the air you breathe and how long you are breathing it. Radon gas is a serious
national concern. The risk of radon-related lung cancer increases the longer you
are exposed although any exposure to radon poses some risk.
Testing for
radon in the air you breathe should be a high priority and the first step for
anyone concerned about radon gas. The US Surgeon General, US EPA, AARST and the
American Lung Association recommend that all homes be tested for radon
gas.
At this time, the EPA does not believe sufficient data exists to
conclude that the types of granite commonly used in countertops are
significantly increasing indoor radon levels.
Radon Sources
Including Granite
Soil, sand, and rock underneath the home are the
primary sources of indoor radon gas. The soil under a house always contains
traces of uranium that eventually decays into radium that then decays directly
into radon. This soil constitutes an enormous surface area for release of radon
gas into the air and into buildings. Materials inside a building such as
concrete, granite, slate, marble, sand, shale and other stones can also contain
traces of radium that release radon with varying intensities. While natural
rocks such as granite may emit some radon gas, the subsequent levels of radon in
the building that are attributable to such sources are not typically high. The
contribution from building materials to the indoor radon concentration is very
dependent upon the building ventilation rate.
Appropriate Radon
Testing Methods
Direct measurements in a building of the gamma
radiation or radon emanation from a material, such as granite, is not a reliable
indicator of radon concentrations that will be in the air you breathe. Attempts
to use such measurements for estimating risk are subject to large errors due to
the:
a) wide variability of radon emanation rates across the
surface of granite.
b) significant variability in ventilation
rates from home to home and room to room.
c) volume of space that
the building material is contained in.
This position
statement does not address the risk, if any, of gamma radiation from indoor
building materials.
Practical Diagnostic
Test
Diagnostic measurements of the radon in the air you breathe can
provide better risk estimates.
Perform a radon measurement according to
testing protocols (specified by EPA or AARST as noted below) in the lowest level
(or lived-in level) of your home.
At the same time, perform another test
in the room where the granite countertop or other suspect building material
exists. You may also want to test in a highly occupied room, like your bedroom.
(Use different rooms if these locations are on the same floor.)
Place
the test devices at least 20 inches off the floor according to testing protocols
and at least 20 inches away from the countertop or suspect material. Carefully
follow all manufacturers' test kit instructions.
You may also contact a
State licensed or nationally certified radon measurement professional to conduct
the measurements for you.
If any of the test results are at or above the
EPA recommended action levels retest these areas to confirm the initial
results.
Interpreting Radon Test Results
For
guidance on test results and protocols for measurements of radon in the air, see
documents such as EPA's Citizens Guide to Radon or other EPA publications at http://www.epa.gov/radon/pubs. Other information and publications for
measuring radon in the air for home and multi-family dwellings can also be found
at http://www.aarst.org.
If confirmed measurements are at, or above, the
EPA recommended action levels, contact a State licensed or nationally certified
mitigation professional to fix the home to reduce the radon
levels.
Reducing Radon Concentrations
The best
approach to reduce radon in the home is to install an active soil
depressurization system (ASD) and reduce the entry of radon coming from the
soil. In some cases, increasing the entry of outdoor air to the home is an
appropriate method to reduce radon levels by dilution and improve indoor air
quality. Both of these methods require a qualified radon mitigation professional
to design and install the appropriate radon reduction system. Only in extreme
cases would removal of the granite be necessary to reduce the radon
concentration, assuming appropriate measurements confirm it as the significant
source.
In Conclusion
Testing the air you breathe is
the best method to determine your risk from radon, whether the source of the
radon is from the soil or from a material inside the building.
We
support peer-reviewed research to identify and quantify the contributions of
various building materials to indoor radon concentrations.
This
statement was provided by the Science and Technical Committee of the American
Association of Radon Scientists and Technologists (AARST).
This
statement was prepared by AARST professionals with no external funding or other
support. The sole purpose of this statement is educational and to reduce lung
cancer deaths from elevated concentrations of indoor
radon.
For More Information Contact:
Peter
Hendrick, Executive Director
AARST
14 Pratt RD
Alstead, NH
03602
603-756-9259
director@aarst.org
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