Kristen Miller M.S., Jeff Sullivan, MD, MHS, and Joel Kaufman, MD, MPH
Scientists have known that particulate air pollution is harmful to the respiratory and cardiovascular systems, but new research by NIEHS grantees at the University of Washington shows that the risk in post-menopausal women is much higher than previously thought. The increased risk comes from the fine particulate matter typically produced by automobile exhaust. The particles damage arteries in the heart and brain.
The risk proved to be about three times higher than previously estimated. The scientists found that the greater the level of the fine particulate pollution, the greater the risk of cardiovascular disease and death. Even slight elevations in particulate matter resulted in significant increased the risk significantly.
The study participants were part of the fifteen-year Women’s Health Initiative conducted by the Fred Hutchinson Cancer Research Center. The study has produced important results related to heart disease, breast and colorectal cancer, and osteoporosis. The scientists analyzed the medical records of more than 66,000 postmenopausal women from 36 cities and followed them for six years. Particulate air pollution was measured by monitors placed near the subjects homes. The size of the particles measured was smaller than 2.5 microns in diameter. During the study, 1,816 women had heart attacks, strokes, or were diagnosed with arterial diseases–261 died.
The risk of dying from heart attack or stroke increased 76 percent for each ten microgram increase in particulate pollution. The annual average exposure was 13,5 micrograms per cubic meter of air. The EPA standard is 15 micrograms–levels higher than that can result in sanctions being imposed on cities.
Although the actual biological effects of particulate exposure are unknown, the scientists speculate that the particles cause inflammation in the lungs that spreads to the arteries, increasing arterial disease and the likelihood of heart attack and stroke. To further investigate these effects, they have another study underway in 7,000 people of various races around the country that will study how air pollution affects arterial health over time.
Citation: Miller KA, Siscovick DS, Sheppard L, Shepherd K, Sullivan JH, Anderson GL, Kaufman JD. Long-term exposure to air pollution and incidence of cardiovascular events in women. N Engl J Med. 2007 Feb 1;356(5):447-58.