LOS ANGELES, Feb. 1 (Xinhua) -- Air pollution poses a greater risk to postmenopausal women, making them more vulnerable to cardiovascular disease, said a new study.

    Postmenopausal women who live in areas with higher air pollution levels have a higher risk of developing cardiovascular disease and of dying from it, said the study by researchers at the University of Washington.

    The higher and longer the exposure to air pollution, the bigger the threat to postmenopausal women, warned the study appearing on the Health Day News website.

    The risk of heart disease is higher than previously thought, and there can be substantial variations within individual cities, said the study.

    "The risk of having a cardiovascular event, that is, a heart attack, stroke or needing bypass surgery, or of dying of a cardiovascular cause, was increased," said study senior author Dr. Joel Kaufman, professor of environmental and occupational medicine and epidemiology at the University of Washington.

    The study is the first to look at new cases of cardiovascular disease, not just death. It was also the first to look at air pollution levels within cities.

    Cardiovascular disease is the leading cause of death in the United States, accounting for one in three deaths.

    Reducing fine particulate air pollution could result in less cardiovascular disease and fewer deaths, the study stated.

    Fine particulate matter is comprised of tiny particles of soot or dust carried in the air. "They mostly come from combustion of fossil fuels, although vegetative burning has an impact in some cities," Kaufman said.