WASHINGTON, Dec. 12 -- The U.S. Department of Health and Human Services' National Institutes of Health issued the following news release: Media Advisory An observational study of more than 6,500 adults is one of the most detailed in the U.S. A large study found that greater exposure to long-term air pollution was linked with increased risks for blood clots that can occur in deep veins, which, if untreated, can block blood flow and cause serious complications, even death. These findings came   more