1 Marsico Lung Institute, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States.
2 Division of Rheumatology, Allergy, and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States.
3 Division of Pulmonary and Critical Care Medicine, Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States.
4 Department of Environmental and Occupational Health, University of Pittsburgh Medical Center, Pittsburgh, PA, United States.