Chronic Air Pollution Linked to Heart Attacks and Strokes in Older Women
Women living in areas with higher levels of air pollution have a greater risk of developing heart disease and dying from cardiovascular causes, according to a University of Washington study published in the New England Jouranl of Medicine. The Women’s Health Initiative (WHI)study is one of the largest of its kind involving more than 65,000 women, ages 50 to 79, living in 36 U.S. cities.
Researchers studied women who did not initially have cardiovascular disease, following them for up to nine years to see who went on to have a heart attack, stroke, coronary bypass surgery, or died from cardiovascular causes. They linked this health information with the average outdoor air pollution levels near each woman’s home, and found that long-term exposure to higher fine particle pollution levels posed a significant hazard — much higher than previously thought — for development of cardiovascular disease.
The resarchers found that each 10-unit increase in fine particulate matter level was linked to a 76 percent increase in the risk of death from cardiovascular disease, after accounting for known risk factors such as blood pressure, cholesterol, and smoking. Higher long-term average levels of fine particles also resulted in a higher overall risk of heart attacks and strokes.
The authors conclude: “Our study provide evidence of the association between long-term exposure to air pollution and the incidence of cardiovascular disease. Our study confirms previous reports and indicates that the magnitude of health effects may be larger than previously recognized. These results suggest that efforts to limit long-term exposure to fine particulate pollution are warranted.”
An accompanying editorial by Dr. Douglas W. Dockery and Dr. Peter H. Stone of the Harvard School of Public Health and Harvard Medical School characterizes the policy implications of the study: “The evidence that has accumulated thus far regarding the health threat from PM2.5 pollution is convincing enough to have prompted the Environmental Protection Agency (EPA) to lower short-term (24-hour) standard for fine particulate concentration that communities must achieve. Unfortunately for public health, the EPA failed to follow the recommendaton of its science advisors and reduce the long-term standard for fine particles. The findings of the WHI study strongly support the recommendaton for tighter standards for long-term fine particulate air pollution.”
Miller KA, Siscovick DS, Sheppard L, Shepherd K, Sullivan JH, Anderson GL, Kaufman JD. N Engl J Med 2007; 356:447-458. Available online: http://content.nejm.org/cgi/content/full/356/5/447?ijkey=2eeac663fe9da62089808800aa30cad1a3dfdac6
Dockery DW, Stone PH. Cardiovascular Risks from Fine Particulate Air Pollution. N Engl J Med 2007; 356:511-513. Available online: http://content.nejm.org/cgi/content/full/356/5/511
