Affiliation: | a Channing Laboratory, Boston, MA 02115, USAhb Division of Pulmonary and Critical Care Medicine, Brigham & Womens Hospital, Boston, MA 02115, USAc Department of Medicine, University of Pittsburgh Medical Center, PA 15213, USAd Division of Pulmonary and Critical Care, Fallon Clinic, Worcester, MA 01605, USAe Department of Work Environment, University of Massachusetts Lowell, Lowell, MA 01854, USAf Harvard Vanguard Medical Associates, Boston, MA 02115, USAg Division of Pulmonary and Critical Care Medicine, Morehouse School of Medicine, Atlanta, GA 30310, USA |