Post-menopausal women exposed to high concentrations of air pollutants, are at a higher risk of cardiovascular problems than previously thought, reveal a new study.
The study conducted by Women's Health Initiative, which is funded by the government of America, has brought out findings that urge the Environmental Protection Agency (EPA) to raise its limits on air pollutant concentrations.
Though the EPA had tightened its daily limit for these tiny specks, known as fine particulates in September, it has left the average annual limit untouched, allowing a concentration of 15 millionths of a gram for every cubic meter of air.
This study was carried out on 65,000 women aged 50 to 79 years across 36 cities in the U.S and commenced in 1994. All participants were free of any cardiovascular diseases at this time.
Nine years on, scientists have examined data and established a link between heart problems and the quality of air, which the women were exposed to.
Their findings have been published in the New England Journal of Medicine.
According to the study results, 1,816 of the participants had suffered a heart attack or stroke, had undergone heart bypass surgery or had died from cardiovascular causes during the last 9 years.
Most significantly, each 10-microgram rise of average particulate levels carried a 76% increase in the chances of dying from any cardiovascular cause. That is several times higher than in a study by the American Cancer Society.
The average particulate levels in the study for the 36 cities ranged from about four to almost 20 micrograms per cubic metre of air.
The study is the first to look at new cases of cardiovascular disease, not just death and also the first to look at air pollution levels within cities.
Says Kristin Miller, from the University of Washington, one of the authors of the paper," Our findings show that both what city a woman lived in and where she lived in that city affected her exposure level and her disease risk."
Fine particulate matter that contributes to air pollution can be described as that derived from combustion of fossil fuels, vegetative burning, power plants, coal burning and motor vehicle exhaust, especially diesel. It comprises of fine soot particles and dust, which is carried along in the air.
Scientists are not sure how fine particulate air pollution increases these health risks, although it is possible that inhaling the particles may hasten the development of atherosclerosis or hardening of the arteries.
"We really need to work harder to lower these levels, and we need to think about pollution as a risk factor, like smoking and diabetes and cholesterol. We need to think of pollution as a cause of health effects now", is what Dr. Joel Kaufman, professor of environmental and occupational medicine and epidemiology at the University of Washington concludes.
Says Professor Jeremy Pearson, associate medical director of the British Heart Foundation, " When localized air pollution is particularly high, people with chronic lung disease or coronary heart disease should avoid staying outside for long periods."