A high proportion of children admitted to Wellington Hospital in winter are exposed to harmful housing conditions, according to a new University of Otago Wellington study.

The study was carried out by a group of fourth-year medical students who interviewed parents and caregivers of 106 hospitalised over a two week period in July 2012. Many of the children were exposed to harmful housing conditions, particularly cold (50%) dampness (30%), mould (24%) and overcrowding (21%). Many were also exposed to second-hand smoke (38%).

Exposure to harmful conditions was particularly common for Maori and Pacific children and those living in poor neighbourhoods.

University of Otago Wellington Professor Michael Baker says New Zealand research shows that exposure to crowded, cold, damp and mouldy housing, and second-hand smoke, all contribute markedly to childhood diseases, but there are limited data on the proportion of hospitalised children exposed to these hazards.

"This latest study adds to growing evidence about the harmful and costly effects of poor housing on child health in New Zealand, and supports the need for a housing 'warrant of fitness' and other measures to improving housing conditions," Professor Baker says.

Trainee doctor Ashton Kelly says it was an "eye opener" to interview the parents of children acutely admitted to hospital and hear about the poor housing conditions many of them live in.

"This study highlighted that we are treating children in hospital and potentially sending them home to situations that are dangerous to their health. This is most likely going to result in them returning to hospital or at least to their GP, and does not constitute effective healthcare delivery," Mr Kelly says.

"It seems self-evident that New Zealand needs to put more effort into preventing these children getting sick in the first place."

New Zealand's housing stock needs to be drastically improved to provide safe living for children, improve their health and decrease their hospitalisation. This is particularly relevant for rental housing, he says.

Almost 80% of and interviewed in the study said they would use a free service that involved someone coming to their house to look at its condition and things that affect the health and safety of children, he says.

The introduction of a "warrant of fitness" for all to ensure private-sector landlords meet minimum quality standards was a key recommendation in the recent report of the Children's Commissioner's Expert Working Group on Solutions to child Poverty.

The University of Otago Wellington study appears in today's issue of the New Zealand Medical Journal.

Journal information: New Zealand Medical Journal