1. Pulmonary Section, Veterans Affairs Ann Arbor Medical Center , Ann Arbor, Michigan , USA
2. Division of Pulmonary and Critical Care Medicine, University of Michigan , Ann Arbor, Michigan , USA
3. Civil and Environmental Engineering, Virginia Tech , Blacksburg, Virginia , USA
4. Division of Infectious Diseases, Department of Medicine, Emory University School of Medicine , Atlanta , Georgia , USA
5. Departments of Epidemiology and Global Health, Emory Rollins School of Public Health , Atlanta , Georgia , USA