BEIJIGN, Feb. 16 (Xinhuanet) -- Fine and ultrafine
particles in air pollution may raise stroke risk, though the heightened risk
occurs only in warm weather, according to a Finnish research report Thursday.
Earlier research has linked air pollution with heart
attack, but this is the first study to look at ultra-fine particle air pollution
and stroke.
The study, published in Stroke, shows a rise in fatal
stroke risk among people 65 and older on warm days when the air was laden with
fine particle pollution.
Dr. Jaana Kettunen, from the National Public Health
Institute in Kuopio, and colleagues compared air pollution levels from 1998 to
2004 with the number of stroke deaths among elderly subjects living in Helsinki,
a city known to have relatively little air pollution.
A total of 1,304 stroke deaths in the warm season and
1,961 in the cold season were logged in during the study period.
Kettunen suggested that people might be more
vulnerable to air pollution in warmer months, because they are outside and open
their windows and doors more than in cold months and, therefore, their exposures
are higher. In addition, differences in the makeup of air pollution between
seasons may play a role.
The tiny particles in the air of Helsinki are
produced mainly by combustion - wood-burning stoves, cars and trucks, and
industrial emissions. They are microscopic in size: less than 1/30th the width
of a human hair. A weather phenomenon called a temperature inversion has trapped
the dirty air over the metro area, allowing the pollution to accumulate.
"We suggest that on high pollution days, elderly
people should avoid spending unnecessary time in traffic, whether in a vehicle
or walking, especially if they suffer from cardiovascular diseases, to lower
their exposure to pollutants," said Kettunen.
(Agencies)
