1. Division of Pulmonary and Critical Care Medicine and
2. Department of Environmental Health and Engineering, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland;
3. Department of Environmental and Occupational Health Sciences and
4. Section of Pulmonary and Critical Care, Dartmouth-Hitchcock Medical Center, Geisel School of Medicine, Hanover, New Hampshire;
5. Center for Environmental Medicine, Asthma and Lung Biology, Division of Allergy and Immunology, University of North Carolina, Chapel Hill, North Carolina;
6. Division of Pulmonary and Critical Care Medicine, University of Washington, Seattle, Washington;
7. Division of Pulmonary and Critical Care, Presbyterian Hospital, Columbia University Medical Center, New York, New York;
8. Department of Internal Medicine, Weill Cornell Medical College, New York, New York;
9. Division of Pulmonary and Critical Care, University of Michigan Health System, Ann Arbor, Michigan;
10. Division of Pulmonary and Critical Care Medicine, Department of Medicine, and Cardiovascular Research Institute, University of California, San Francisco, San Francisco, California;
11. Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, University of Utah, Salt Lake City, Utah;
12. Division of Pulmonary and Critical Care Medicine, Department of Medicine, University of California, Los Angeles, Los Angeles, California; and
13. Pulmonary, Critical Care, Allergy, and Immunologic Medicine, Department of Internal Medicine, Wake Forest University, Winston-Salem, North Carolina