1. Section of Pulmonary and Critical Care Medicine, Yale University School of Medicine, New Haven, CT 06520
2. Occupational and Environmental Medicine Program, Yale University School of Medicine, New Haven, CT 06520
3. the Departments of Therapeutic Radiology, Yale University School of Medicine, New Haven, CT 06520
4. Department of Internal Medicine, Yale University School of Medicine, New Haven, CT 06520
5. the Departments of Epidemiology and Public Health, Yale University School of Medicine, New Haven, CT 06520