1. Faculty of Medicine, Department of Public Health and General Practice; Norwegian University of Science and Technology; Trondheim Norway
2. Department of Circulation and Medical Imaging NTNU; Norwegian University of Science and Technology; Trondheim Norway
3. Department of Thoracic and Occupational Medicine; Trondheim University Hospital; Trondheim Norway
4. Department of Emergency Medicine, Massachusetts General Hospital; Harvard Medical School; Boston Massachusetts USA
5. Department of Epidemiology; Harvard School of Public Health; Boston Massachusetts USA
6. Faculty of Medicine, School of Epidemiology, Public Health and Preventive Medicine; University of Ottawa; Ottawa Ontario Canada