Natural stone manufacturers india,Natural stone suppliers,Natural stone exporters india,Natural stone paving,Jaipur,Rajasthan,india
Natural stone Introduction
Natural stone is a popular choice for countertops in homes throughout the United
States. These surfaces are typically referred to as “granite” but in fact can consist
of a variety of stone types that includes actual granite and marble. Regardless of
the specific type, all natural stones used as countertops are composed of several
major minerals and numerous minor constituents. Radium is one of the minor
components of some countertops made from natural stone.
Radon, produced from radium, is a radioactive gas that occurs naturally in the
environment and is present in outdoor and indoor air throughout the world.
Radon has been found to pose a health risk for exposed individuals as the
concentration increases. Useful benchmarks for evaluating exposure include
action levels recommended by the EPA, baseline concentrations of radon in
indoor and outdoor air, and goals for radon indoors established by the Congress
of the United States.
In considering the public’s health, we ask an important question - how much do
natural stone countertops contribute to the amount of radon inside U.S. homes in
comparison to those benchmarks? The answer is very little, according to the best
scientific evidence that is available at this time.
The objective of this white paper is to explain why this is the case and to
demonstrate this conclusion with three robust yet simple examples that cover a
range of realistic household conditions.
We begin with a summary of radon emissions from natural stone countertops
reported in the scientific literature; next, describe how ventilation influences 3
levels of radon in indoor air of homes; then present estimates of radon levels in
homes that could arise from natural stone countertops; and conclude by
comparing those levels to the benchmark values mentioned above.
Radon Emissions from Stone Countertops
The amount of radon released from a natural stone countertop in a home depends
on the surface area of countertop in the home and the amount of radon released
per unit area of stone. Sufficient information is available to derive reasonable
estimates for both of those parameters.
An average kitchen with stone countertops has a working surface area of
approximately 50 square feet (ft2) according to a large sample of sales data
provided to Environmental Health & Engineering, Inc. by the Marble Institute of
America, while a typical bathroom installation is approximately 18 ft2 of stone.
Accounting for both the kitchen and bath, the underside face of the counter, and
the thickness of the stone (about 1.2 inches), a typical installation of natural
stone countertop includes a total surface area of approximately 140 ft2. To
produce the most health protective estimates, we assume that the entire surface
area is open to the room and contributing radon to the indoor air.
Over 500 measurements of radon released from granite and marble have been
reported in peer reviewed articles published in the leading scientific journals that
focus on radiation and health.1-17 Stones included in those studies were mined
from quarries throughout the world and reflect the diversity of stones in the U.S.
market. Radon emissions, sometimes called the exhalation rate, are expressed as
the amount of radioactivity released per square foot of stone per hour
(pCi ft-2 h-1). As shown in Figure 1, most of the stones tested so far have an
exhalation rate between 0.1 and 5 pCi ft-2 h-1, while the average and maximum
values are 1.9 and 34 pCi ft-2 h-1, respectively.
Natural stone manufacturers india,Natural stone suppliers,Natural stone exporters india,Natural stone paving,Jaipur,Rajasthan,india
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