1 Wellington Asthma Research Group, Department of Medicine, University of Otago, Wellington, New Zealand. Electronic address: caroline.shorter@otago.ac.nz.
2 Department of Health Protection, National Institute for Health and Welfare (THL), Kuopio, Finland.
3 He Kainga Oranga/Housing and Health Research Group, Department of Public Health, University of Otago, Wellington, New Zealand.
4 Centre for Public Health Research, Massey University, Wellington, New Zealand.
5 Wellington Asthma Research Group, Department of Medicine, University of Otago, Wellington, New Zealand.