April 7, 2010
Air Pollution Might Cause Stroke Death Rates To Rise
United Kingdom study findings show that traffic-related air pollution may be linked to a higher death rate among people who initially survived strokes, according to a recent Reuters report.
Dr. Ravi Maheswaran at the University of Sheffield, along with colleagues, found more deaths among those exposed to higher estimated traffic-related pollution for over a decade. They studied 3320 men and women living in a specific south London region that had a first stroke between 1995 and 2005.
The researchers used 2002 estimates of two common traffic pollutants linked to breathing difficulties and other health problems.
Their report shows risk of dying increased 28 percent when nitrogen dioxide levels rose by 10 micrograms per 3 square meters of air. They said that another increase in particulate matter increased death risk by 52 percent.
This was typical for all of London. The low-pollution areas typically did not have major roads running through them. The higher pollution areas had nitrogen dioxide levels that the U.S. Environmental Protection Agency considers average.
The team said there were more deaths in the higher polluted neighborhoods, about 59 percent of the patients in high nitrogen dioxide neighborhoods and 58 percent in high particulate matter areas.
That compared to the 53 percent of patients in an area less polluted by high nitrogen dioxide and about 53 percent of patients in an area less polluted by high particulate matter.
Risk for death remained higher with greater air pollution exposure after the investigators took into account a number of other factors associated with stroke death including age, gender, ethnicity, smoking and alcohol use, high blood pressure, heart disease, and diabetes.
Maheswaran and colleagues wrote in the journal Stroke that if future investigations show air pollution causes death among stroke patients, a 10 microgram reduction in nitrogen dioxide exposure "would be associated with a 22 percent decrease in mortality after stroke."
Dr. Jiu-Chiuan Chen of the University of Southern California Keck School of Medicine said it is unclear why stroke patients may be more vulnerable to the long-term effects of air pollution.
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