2004-12-7
I'm Gwen Outen with the VOA Special English Health Report.
American researchers say they have found the strongest link yet
between ozone pollution and damage to health. Their findings show
that short-term increases in ozone lead to higher death rates in
cities.
Ozone is a form of oxygen. The gas is produced naturally in the
upper atmosphere to protect the Earth against radiation from the
sun. But human activity can also create ozone in the lower
atmosphere.
Gasses from vehicles and industry react with sunlight to form
this ozone. Levels usually increase in the warmer months. Ozone is
the main chemical in smog, the air pollution that is a combination
of fog and smoke.
Ozone has been linked to heart and lung problems especially, and
to higher rates of hospital cases.
Researchers from Yale University and Johns Hopkins University did
the study. Michelle Bell of Yale was the lead investigator. The
Journal of the American Medical Association published the results.
The researchers collected information on ninety-five American
cities. These contain about forty percent of the national
population. The study compared deaths rates to ozone levels between
nineteen eighty-seven and two thousand.
The research suggests that even a small increase in ozone, ten
parts per thousand million, can lead to higher death rates the
following week. The study found that the average daily number of
deaths rose point-five percent. Heart and lung related deaths rose
point-six percent. And deaths among older people rose point-seven
percent.
The researchers controlled for other possible causes of death,
such as hot weather or pollution from particle matter. The study
linked even a single day of increased ozone to more deaths the
following week.
The study is one of the largest ever done of ozone and death
rates. The researchers note that ozone is widespread in the United
States and many other countries.
The United States Environmental Protection Agency is re-examining
its air pollution rules. The current limit for ozone is eighty parts
per thousand million for an eight-hour period. Limits were higher in
the past. But the researchers say they found an increase in deaths
even below the current levels.
They say that if ozone decreased by one-third in those
ninety-five cities, almost four thousand lives per year might be
saved.
This VOA Special English Health Report was written by Cynthia
Kirk. I'm Gwen Outen.