Scientists have long known that air pollution damages the lungs and, more recently, that it harms the arteries and the heart as well. Now they've found that particulate pollution, the cocktail of soot, diesel exhaust, chemicals, metals, and aerosols that circulates above and beyond countless American cities, increases the risk of developing dangerous blood clots in the veins of the legs, too. Deep vein thrombosis, as these common clots are called, can become lethal pulmonary embolisms when portions flake off and lodge in the lung. These lodged clots kill a third of people who have them when left untreated.
According to a study published today in the Archives of Internal Medicine, even modest increases in particulate exposure significantly increase the risk of deep vein thrombosis. The researchers found, for example, that each 10-micrometer-per-cubic-meter increase in particulates—approximately the difference between Pittsburgh and cleaner Anchorage—is associated with a 70 percent increase in the risk. "That's a surprisingly high figure," says Joel Schwartz, the senior author of the study and a Harvard University environmental epidemiologist, noting, however, that additional studies are needed to confirm the finding.
Schwartz and other experts caution that the absolute risk any one individual faces remains small and that there's only so much that an individual person can do to cut his exposure to particulate matter. But there are certain steps people can take to cut their exposure to particulates. The most important, they say, is to avoid exercising outdoors during high-pollution days and near major roadways. Roadways are major sources of fine and ultrafine particulate pollution, a type that scientists are beginning to recognize as particularly dangerous.
The Environmental Protection Agency, in conjunction with other government agencies, operates a useful website called AIRNow that offers continually updated air pollution forecasts. With EnviroFlash, users can arrange to have automatic air pollution updates sent to their E-mail accounts. The AIRNow website has another valuable tool—AirCompare—that allows people to compare and graph the number of days that selected counties have unhealthy pollution levels.
On May 1, the American Lung Association released its 2008 State of the Air report, another helpful resource. The report, which includes rankings of cities most and least polluted by particulate pollution, features an online database that allows users to call up detailed information about the impact of air pollution in their local areas. The five most polluted cities for short-term particulate pollution are Pittsburgh; Los Angeles; Fresno, Calif.; Bakersfield, Calif.; and Birmingham, Ala. People living in these or other heavily polluted cities who have health problems may want to factor in air pollution if they're considering a move, experts say, and should avoid living near major roadways if possible.
The actions of government regulators who set pollution standards have the biggest impact on an area's air pollution levels, but there are small steps individuals can take to keep their particulate emission levels low, too. The Utah Department of Environmental Quality offers 50 steps people can take to choose clean air that include purchasing Energy Star energy efficient products, keeping vehicles well tuned, and keeping all paints and solvents in airtight containers. In its report, the American Lung Association calls for people to drive less, limit their electricity use, and avoid burning wood or trash. For people who use wood stoves, the Environmental Protection Agency offers advice on clean burning fuel choices. Eliminating tobacco smoke and reducing the use of candles and fireplaces, according to the agency, are other ways to reduce indoor particulate pollution loads.