DAVIS, Calif., Jul 24, 2009 (UPI via COMTEX) -- The elderly are warned to avoid
outdoors during high ozone levels but ozone has a negative effect on lung
function in healthy adults, U.S. researchers said.
Researchers at the University of California, Davis, recruited 31 healthy
non-smoking people to participate in 6.6-hour sessions during which they were
exposed to ozone at 60, 70, 80 or 87 parts per billion, or filtered air, while
undergoing six 50-minute bouts of moderate exercise followed by 10-minute
breaks. A 35-minute lunch break separated the third and fourth bouts of
exercise.
Lung function for each subject was assessed before, during and after exposure,
and each individual answered a questionnaire evaluating subjective symptoms.
"The National Ambient Air Quality Standard for ozone was recently revised to set
lower limits for ozone concentrations. Our research indicates that the threshold
for decrements in ozone-induced lung function in healthy young subjects is below
this standard," Edward Schelegle said in a statement. "Specifically, we found
that 6.6 hours exposure to mean ozone concentrations as low as 70 parts per
billion have a significant negative effect on lung function, even though the
current NAAQS standards allow ozone concentrations to be up to 75 parts per
billion over an eight-hour period."
The study is published in the American Journal of Respiratory and Critical Care
Medicine.
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