1. Department of Paediatrics: Child and Youth Health, Faculty of Medical and Health Sciences; The University of Auckland; Auckland; New Zealand
2. Medical Research Institute of New Zealand; Wellington; New Zealand
3. Institute of Environmental Medicine, Karolinska Institutet; Stockholm; Sweden
4. Wellington Asthma Research Group; Wellington School of Medicine; Wellington; New Zealand
5. Respiratory Medicine and Allergy Units; ‘Virgen de la Arrixaca’ University Children's Hospital, University of Murcia; Murcia; Spain
6. Institute of Epidemiology and Social Medicine, University of Muenster; Muenster; Germany