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Researchers report high outdoor radon concentrations in Iowa, Minnesota
IOWA CITY, Iowa -- Researchers at St. John's University in Collegeville,
Minn. and the University of Iowa report that unusually high outdoor radon
concentrations have been found in Iowa and Minnesota.
Their study indicates that in some areas of Iowa and Minnesota, the
outdoor average radon concentration actually exceeds the national indoor
average radon concentration of 1.4 picoCuries per liter (pCi/L) of air
for single family homes. The study results are reported in the February
issue of Environmental Health Perspectives, a publication of the National
Institute of Environmental Health Sciences.
The researchers measured the annual average atmospheric radon concentration
at 111 locations in Iowa and 64 locations in Minnesota. Environmental
Protection Agency surveys have estimated the average outdoor radon concentration
in the United States is approximately 0.4 pCi/L.
However, "the average radon concentrations found in the outdoor
air in Iowa was twice the national average. In fact, some areas of western
Iowa exceeded 1 pCi/L," said R. William Field, Ph.D., UI associate
research scientist in preventive medicine and environmental health.
Daniel Steck, a physics professor at St. John's University and lead
author on the paper, noted that, "even in Minnesota the average outdoor
radon concentration was higher than expected." The average outdoor
radon concentration in Minnesota was 0.6 pCi/L with some areas as high
as 1.5 pCi/L.
The researchers, which also included Charles Lynch, M.D., Ph.D., UI
professor of preventive medicine and environmental health, pointed out
that the findings indicate that outdoor radon exposure should be accounted
for in studies examining the relationship between radon exposure and lung
cancer. Previous epidemiologic studies that examined the risk associated
with radon exposure failed to consider the dose from outdoor radon concentrations.
The outdoor radon monitoring in Iowa was part of a National Institutes
of Health-sponsored epidemiologic study in Iowa, which examined the health
risks of radon exposure. The findings of that study will be out later
Field said he was not totally surprised by the high outdoor radon concentrations
in Iowa. "Previous studies have pointed out that Iowa has the highest
mean indoor radon concentration in the United States. It follows that
Iowa would likely have the highest outdoor mean radon concentrations in
the nation," he said.
Field noted that the higher radon concentrations are due primarily to
the glacial deposits that have occurred more than 10,000 years ago "The
radium found in glacial tills is the primary source of both indoor and
outdoor radon in the upper Midwest," he said.
The best way to reduce overall exposure to radon is to test your home
and take action to reduce elevated indoor radon concentrations, Field added.
The Environmental Protection Agency (EPA) suggests homeowners reduce the
radon concentrations in their homes if the yearly average home radon concentration
exceeds 4 pCi/L. More information on radon testing and mitigation is available
toll-free from the EPA at (800) SOS-RADON.