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Over the years, air pollution has been linked to a variety of health problems such as heart attacks, premature death, decreased lung function and asthma. Most recently, researchers have found that pollution from particulate matter, the tiny particles of carbon, metals, nitrates and other materials which result from car emissions, chemicals from factories, aerosols, dust, pollen and mold spores, also increases the risk of deep vein thrombosis, which are blood clots in the legs or thighs. Thrombosis can become lethal pulmonary embolisms when portions break off and lodge in the lung. Left untreated, these lodged clots kill one-third of people who have them.
Dr. Andrea Baccarelli and colleagues of the Harvard School of Public Health in Boston found the link after comparing exposure to particulate pollution on 870 people in the Lombardy region of Italy who had been diagnosed with deep vein thrombosis between 1995 and 2005, and 1,210 people who did not have deep vein thrombosis. After compensating for other environmental and health factors, the researchers found that for every increase in particulate matter of 10 micrograms per square meter, the risk of deep vein thrombosis increased by 70 percent. Tests also showed that the blood of those with higher levels of exposure took less time to form clots.
“This is the first time that anyone has connected air pollution with deep vein thrombosis,” said Dr. Baccarelli, who led the study and is now an assistant professor of environmental health at the University of Milan. “Several studies in animal models and in humans have shown that particulate matter, inhaled into the lungs, causes inflammation in the lungs. The inflammation can expand the cell body, so that the incidence of coagulation is increased.” Coagulation is the formation of clots that can block blood vessels.
In an editorial which accompanied the study findings, Dr. Robert Brook, an assistant professor of internal medicine at the University of Michigan in Ann Arbor, said if the findings are corroborated by future research it may prove that “the actual totality of the health burden posed by air pollution, already known to be tremendous, may be even greater than ever anticipated.” Dr. Brook added that, even though “the results are very positive,” there needs to be further studies. Dr. Baccarelli agreed and said, “We are working on that. We are seeking additional populations in which the same link between air pollution and deep vein thrombosis can be evaluated. We also hope that some of our colleagues elsewhere will be pushed to conduct other studies.”
The researchers said the findings, published in the May 12 issue of the Archives of Internal Medicine, “give further substance to the call for tighter standards and continued efforts aimed at reducing the impact of urban air pollutants on human health.” Currently in the U.S., the AQI is an index for reporting daily air quality. It tells you how clean or polluted your air is, and what associated health effects might be a concern for you, focusing on effects you may experience within a few hours or days after breathing polluted air. The Environmental Protection Agency (EPA) calculates the AQI for five major air pollutants regulated by the Clean Air Act; ground-level ozone, particle pollution, carbon monoxide, sulfur dioxide, and nitrogen dioxide. You can find continually updated air pollution forecasts on AIRNow, a website operated by the EPA and other government agencies. The website features AirCompare, which allows people to compare and graph the number of days that selected counties have unhealthy pollution levels.
The American Lung Association recently released another helpful resource, its 2008 State of the Air report. This report includes rankings of cities most and least polluted by particulate pollution and features an online database that allows users to pull up detailed information for their local areas. According to the report, the five most polluted cities for short-term particulate pollution are Pittsburgh; Los Angeles, Fresno, and Bakersfield in California; and Birmingham, Alabama. Experts say people living in these or other heavily polluted cities and who have health problems may want to factor in air pollution if they are considering relocation. They should also avoid living near major roadways, which are the source of fine and ultrafine particulate pollution.
There are steps people can take to reduce their exposure to particulate pollution. Experts say the most important is to avoid exercising outdoors on days when the pollution levels are high, and steer clear of the major roadways. And while government regulators who set the pollution standards have the largest impact on an area’s air pollution levels, there are also ways that individuals can help to keep emission levels low. In its report, the American Lung Association asks people to drive less, cut down on electricity use, and avoid burning trash or wood. The EPA offers advice on clean burning fuel choices for people who use wood stoves. They also suggest eliminating tobacco smoke and reducing the use of candles and fireplaces as a way of reducing indoor particulate pollution.
