(NaturalNews) Air pollution produced by the burning of fossil fuels can drastically increase people's risk of developing potentially fatal blood clots, according to a study conducted by researchers from the Harvard School of Public Health and published in the"We have known for some time that air pollution has been associated with increased risk of heart attack and stroke," said Beverley Hunt, medical director of the nonprofit organization Lifeblood. "This study shows for the very first time that air pollution also increases the risk of clots in the veins and tells us why."In a condition known as deep vein thrombosis (DVT), blood clots form in the legs. In certain cases, these clots have been known to become dislodged and then travel to the lungs, where they can fatally block the flow of blood. The risk of DVT is known to increase with long periods of immobility, such as on long-haul flights or from spending long hours at a desk without getting up.Researchers compared levels of particulate air pollution around the dwelling places of 870 DVT patients and 1,210 people without the condition, all in the Lombardy region of Italy. They found that for every 10 microgram per square meter increase in particulate concentration, a person's risk of DVT increased by 70 percent.The particulate matter in the study, only about one 40th the width of a human hair, is produced by the burning of fossil fuels, including in vehicle engines and power plants."Given the magnitude of the effects, our findings introduce a novel and common risk factor into the development of DVT," lead researcher Andrea Baccarelli said. "And, at the same time, they give further substance to the call for tighter standards and continued efforts aimed at reducing the impact of urban air pollutants on human health."Sources for this story include: news.bbc.co.uk, www.washingtonpost.com