Air pollution raises risk of cognitive decline, stroke

The Boston Globe “White Coat Notes” blog reports, “Car exhaust and other air pollution, even at levels considered safe by federal regulations, may substantially increase the risk of a stroke, a research team from Beth Israel Deaconess Medical Center has found.”

After reviewing the medical records of more than 1,700 stroke patients in the Boston area over 10 years, “the researchers found a 34 percent increase in the risk of ischemic strokes on days with moderate air quality compared with days when the air was rated good by the US Environmental Protection Agency.”

HealthDay reports, “A lifetime’s exposure to air pollution may contribute to mental decline in older women,” according to the study published in the Archives of Internal Medicine.

Researchers found that “both exposure to fine particulate matter air pollution – less than 2.5 micrometers in diameter, or about 1/30th of the diameter of a human hair – and coarse particulate matter – between 2.5 and 10 micrometers in diameter – were associated with mental declines in women.”

In addition, a second study published in the same journal “found that more people were admitted to a Boston hospital for ischemic stroke on days when levels of fine particulate air pollution were high.”

According to MedPage Today, the second study “found that short-term exposure to fine particulate matter – even at levels allowed by the EPA – can increase the risk of ischemic stroke.”

Researchers “also found that the relationship between higher particulate levels and increased risk of stroke was linear, strongest within 12 hours of exposure, and was seen among patients with strokes caused by large-artery atherosclerosis or small-vessel occlusion but not cardioembolism.”

Both studies were funded by the National Institute of Environmental Health Sciences.

Medscape reports that a commentary on the “the reported association between ambient fine particulate matter, defined as less than 2.5 μm (PM 2.5), and ischemic stroke” said that the study “‘adds to the already strong evidence’ linking PM 2.5 to cardiovascular effects, and [added] that the analysis on cognitive function shows that ‘we may not fully understand the breadth of PM health burdens.'”

A second commentary also pointed out that “these findings are important, because current US and World Health Organization air quality standards focus only on daily and annual PM 2.5 mean concentrations.”

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