Funding for this research was provided by:
Forskningsrådet för Arbetsliv och Socialvetenskap
Norges Forskningsråd (135773/330)
University of Melbourne
Sociedad Española de Neumología y Cirugía Torácica
The Faculty of Health, Aarhus University, Denmark (240008)
The Wood Dust Foundation (444508795)
The Danish Lung Association
The Swedish Heart and Lung Foundation
The Swedish Association Against Asthma and Allergy
The Swedish Association against Heart and Lung Disease
The Bror Hjerpstedt Foundation
The Vårdal Foundation for Health Care and Allergic Research
The Norwegian Asthma and Allergy Association
HelseVest Norway (911 631)
NFR (214123, 230827/F20, 228174)
The University of Iceland Research Fund
The Icelandic GP's Research Fund
The Estonian Science Foundation (4350)
The Estonian Research Council (PUT562)
Australian National Health Medical Research Council
Horizon2020 PHC1 (633212)
The Danish Working Environment Research Fund (17-2015-09 / 20150067134)
Received: 3 April 2018
Accepted: 7 January 2019
First Online: 21 January 2019
Ethics approval and consent to participate
: The study was approved by regional committees of medical research ethics in each study centre according to national legislations. Furthermore, informed written consent was obtained from each participant in all study centres. For list of ethics committees and numbers for each centre, please see ExternalRef removed.
: Not applicable.
: The authors declare that they have no competing interests.
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