Paul James Lioy (May 27, 1947 – July 8, 2015) was a United States environmental health scientist born in Passaic, New Jersey, working in the field of exposure science. He was one of the world's leading experts in personal exposure to toxins. He published in the areas of air pollution, airborne and deposited particles, Homeland Security, and Hazardous Wastes. Lioy was a professor and division director at the Department of Environmental and Occupational Health, Rutgers University - School of Public Health. Until 30 June 2015 he was a professor and vice chair of the Department of Environmental and Occupational Medicine, Rutgers University - Robert Wood Johnson Medical School. He was deputy director of government relations and director of exposure science at the Rutgers Environmental and Occup