1. Department of Community Medicine and
2. Center for Cardiovascular and Respiratory Sciences, West Virginia University School of Medicine, Morgantown, West Virginia, USA
3. Brookmar, Inc., Parkersburg, West Virginia, USA
4. Public Health and Environmental Research Unit, London School of Hygiene and Tropical Medicine, London, United Kingdom
5. Department of Environmental and Occupational Health, Rollins School of Public Health, Emory University, Atlanta, Georgia, USA
6. Department of Environmental Health, School of Public Health, Boston University, Boston, Massachusetts, USA
7. Department of Political Science, Eberly College of Arts and Sciences, West Virginia University, Morgantown, West Virginia, USA