1. Department of Environmental Sciences and Engineering, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
2. Environmental Public Health Division, National Health and Environmental Effects Research Laboratory, U.S Environmental Protection Agency, Research Triangle Park, North Carolina, USA
3. Department of Medicine, Division of Pulmonary and Critical Care Medicine
4. Center for Environmental Medicine, Asthma, and Lung Biology, and
5. Department of Medicine, Division of Cardiology, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA