1. Center for Public Health and Environmental Assessment, Office of Research and Development, U.S. Environmental Protection Agency (U.S. EPA), Research Triangle Park, North Carolina, USA
2. Oak Ridge Associated Universities, Oak Ridge, Tennessee, USA
3. Air Quality Assessment Division, Office of Air Quality Planning and Standards, U.S. EPA, Research Triangle Park, North Carolina, USA
4. Health and Environmental Impacts Division, Office of Air Quality Planning and Standards, U.S. EPA, Research Triangle Park, North Carolina, USA