1. Center for Environmental Medicine, Asthma, and Lung Biology, School of Medicine, University of North Carolina–Chapel Hill, Chapel Hill, North Carolina, USA
2. Institute for Child Health, Division of Clinical Science, University of Western Australia, Perth, Australia
3. Harvard School of Public Health and
4. Harvard Medical School, Boston Massachusetts, USA
5. University of Arizona, Arizona Respiratory Center, Tucson, Arizona, USA
6. National Health and Environmental Effects Research Laboratory, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina, USA
7. University of Arizona, Tucson, Arizona, USA
8. National Institute for Occupational Safety and Health, Morgantown, West Virgina, USA