1. Division of Pulmonary Sciences and Critical Care Medicine, Department of Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado;
2. Department of Medicine, National Jewish Health, Denver, Colorado;
3. Department of Medicine, Icahn School of Medicine at Mount Sinai, Mount Sinai Health System, New York, New York; and
4. Department of Environmental and Occupational Health, University of Pittsburgh School of Public Health, Pittsburgh, Pennsylvania