Researchers have known for some time that air pollution increases the risk of heart attack. Now, a study has shown that air pollution also increases the risk for ischemic strokes – those caused by a blood clot. The study appeared in Stroke: Journal of the American Heart Association, and was conducted by researchers at Boston's Beth Israel Deaconess Medical Center.
Small Percentage – Big Numbers
The increase in ischemic strokes was about one percent on days when air pollution levels were high compared to days when air pollution was low. This seems like a small percentage, but the number become more significant when it is linked to the more than 700,000 strokes suffered by Americans every year (for example, one percent of 700,000 is 7,000 people).
Protocols
Researchers measured air pollution in nine U.S. cities: Birmingham, Alabama; Chicago, Illinois; Cleveland, Ohio; New Haven, Connecticut; Detroit, Michigan; Minneapolis, Minnesota; Pittsburgh, Pennsylvania; Salt Lake City, Utah; and Seattle, Washington. They measured substances put into the air by car and truck exhausts, power plants, refineries, and other sources of polluting particles.
Medicare data from the nine cities was used to determine the number of hospital admissions for ischemic stroke on each day of the study. Admissions were compared to air pollution readings to determine the link between strokes and air pollution.
The average age of stroke patients was 79, and 61 percent of them were women.
Summary and Explanation
The researchers concluded, "Taken together with previous work, these results support the idea that reducing exposure to particulate (air polluting) matter may reduce the risk of strokes and heart attacks."
Living in an area with low levels of air pollution is obviously beneficial. We now know that also includes reduced risk of heart attack and stroke. |
