NEW YORK - Breathing polluted air even for brief intervals may increase the risk of a stroke within the next two hours, a study by Japanese researchers published online in Occupational and Environmental Medicine said. Air pollution has been linked to a variety of lung and breathing problems, but this is the first time a link to stroke is reported.
The research was conducted in 13 big urban areas in Japan. Researchers examined the number of stroke deaths in people aged 65 and older between January 1990 and December 1994. The level of toxic chemicals like nitrogen dioxide, particulate matter, and photochemical oxidants, present in the air in the 13 areas was tabulated on an hourly basis by the researchers.
They found that the risk of having a hemorrhagic stroke was high between April and September. Hemorrhagic stroke occurs when a blood vessel bursts open in the brain. The stroke risk increased in the hours when high levels of particulate matter were observed in the air.
During the four years covered by the study 17,354 residents age 65 or older died from hemorrhagic stroke, while 46,370 succumbed to ischemic stroke. However researchers said that death due to ischemic stroke was not associated with high particulate matter levels.
"During the 4 years covered by this study, there were 443 hours in which the concentration of PM7 was over the 1-hour air quality standard (in Tokyo), and that 49 of those hours (11 percent) occurred on days when the 24-hour mean concentration of PM7 was within the air quality standard for 24-hour periods," the researchers wrote.
Researchers concluded by saying that the effects of polluted air can be very quickly felt in the body since the level of pollutants in the blood showed an increase in 60 seconds time.
