From Name
Field, R W

Health Phys.
2009 Jan;96(1):37-47.
Radon
variations over two decades.
Dan Steck - * Physics Department, St.
John's University, Collegeville, MN 56321.
Long-term exposure
to elevated radon (Rn) concentrations has been linked to increased lung cancer
risk. Year-long measurements of contemporary radon concentrations have been the
"gold standard" for epidemiologists trying to reconstruct past radon
exposures and for homeowners trying to estimate future radon exposure. Random
variations and persistent temporal trends can affect remedial action decisions
and risk coefficients derived from epidemiological studies. Temporal fluctuations
are possible when changes occur in a home's structure, climate, environment, or
occupants. The annual-average temporal radon behavior was studied at 196 sites
in 98 Minnesota houses. Seventeen hundred year-long indoor radon measurements
were made from 1983 to 2000 to determine year-to-year radon fluctuations and
long-term temporal trends. Ten year-long measurements over a span of 13 years
were made at the typical site. The median radon concentration was 120 Bq m. The
median radon concentration of the group of houses showed little year-to-year
variation and no persistent temporal trends. At individual sites, year-to-year
radon variations ranged from 3 to 110%. The median variation was 26%. Climate,
exposure to wind, and radon concentration affected year-to-year variation, but
house age, construction, or measurement floor did not. Some individual sites
showed significantly larger radon changes when modifications were made to the
house structure and heating-ventilation systems. Year-long radon measurements
on the first floor provided better estimates of cumulative radon exposure than
screening measurements. The radon variations observed in this study provide
uncertainty estimates for year-long measurements that could help improve
remediation decision protocols and refine risk estimates from epidemiological
studies.
 
 
R. William Field, PHD, MS
http://myprofile.cos.com/Fieldrw
 
 
 
 
 
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