Affiliation: | (1) Respiratory Medicine Unit, Department of Medicine, Institute of Clinical Medicine, University of Oulu, P.O. Box 5000, 90014 Oulu, Finland;(2) Center for Environmental and Respiratory Health Research, University of Oulu, Oulu, Finland;(3) Institute of Occupational and Environmental Medicine, University of Birmingham, Birmingham, UK;(4) Institute of Health Sciences, University of Oulu, Oulu, Finland |