Air quality and its association with the risk of acute ischemic stroke and risk of cognitive decline in older women are examined in two studies in the Feb. 13 issue of Archives of Internal Medicine, one of the JAMA/Archives
In one study, Gregory A. Wellenius, Sc.D, of Brown University, Providence, R.I., and colleagues evaluated the association between changes in fine particulate matter (PM) air pollution (PM<2.5 µm in diameter [PM2.5]) levels and the risk of ischemic stroke among patients living in the greater Boston area who were admitted between 1999 and 2008 to Beth Israel Deaconess Medical Center.
The authors reviewed the medical records of 1,705 patients hospitalized with ischemic stroke. During the study period, PM2.5 levels in the Boston area did not exceed current EPA
Daily changes in levels of ambient fine particular matter air pollution [PM2.5] have been associated with higher risk of acute cardiovascular events, excess hospitalizations and deaths, researchers write in the study background.
"We found that ischemic stroke risk was 34 percent higher on days with moderate PM2.5 levels compared with days with good levels, according to the EPA's Air Quality Index," the authors comment. Stroke risk was more strongly associated with concentrations of black carbon and NO2 (nitrogen dioxide) markers of traffic pollution than with components linked to nontraffic
In an invited commentary, Robert D. Brook, M.D., of the University of Michigan, Ann Arbor, and Sanjay Rajagopalan, M.D., of the Ohio State University Medical Center, Columbus, write: "Why are these findings important? Current U.S. and World Health Organization air quality standards focus only on daily and annual PM2.5 mean concentrations. There is no biological basis that these specific durations of exposure are required to instigate strokes or other CV (cardiovascular) events."
In another study, Jennifer Weuve, M.P.H., Sc.D, of Rush University Medical Center, Chicago, and colleagues evaluated air pollution, both coarse and fine, in relation to cognitive decline in older women using a study population from the Nurses' Health Study Cognitive Cohort, which included 19,409 U.S. women ages 70 to 81.
Researchers note that very little is known about the role of particulate matter exposure in relation to cognitive
"In this large, prospective study of older women, higher levels of long-term exposure to both PM2.5-10 and PM2.5 were associated with significantly faster cognitive decline," researchers
The researchers comment that these associations were present at levels of PM exposure typical in many areas of the United States.
"Therefore, if our findings are confirmed in other research, air pollution reduction is a potential means for reducing the future population burden of age-related cognitive decline, and eventually,
In an invited commentary, Rajiv Bhatia, M.D., M.P.H., of the San Francisco Department of Public Health, writes: "The strong and growing evidence of the harms of PM2.5 demands scrutiny of societal efforts to reduce exposure."
Arch Intern Med.. 2012;172:229-234;Ambient Air Pollution and the Risk of Acute Ischemic Stroke