WASHINGTON, Feb. 13 -- The University of Notre Dame Kroc Institute for International Peace Studies researchers have developed a new data driven tool to track cross border air pollution finding that 40 percent of premature deaths linked to PM 2.5 in the U.S. stem from emissions that travel across state lines. The study published in Environmental Research Letters examines microscopic particulate matter known as PM 2.5 which contributes to an estimated 100000 premature deaths annually in the U.S.   more