Half of New Zealand homes have mould in them and new research shows a link between this and asthma in children.
A study carried out by researchers at the University of Otago, Wellington, shows that mould makes asthma worse but can also lead to the development of a first asthma attack in young children.
The study, published on Wednesday in the international journal Indoor Air, was funded by the Health Research Council of New Zealand.
It investigated the homes of 150 children who had visited their GPs for their first prescribed asthma medication, and compared them to the homes of 300 matched children who had never wheezed.
"We found that mould and leaks were more likely to be found in the bedrooms and homes of children who had just started wheezing compared to the children who had never wheezed," says the study's lead author, Dr Caroline Shorter.
"The amount of mould present in the bedroom made a difference - the more mould, the greater the risk that children would start wheezing.
"We urgently need to improve the quality of our childrens' home environments."
One in six adults and one in four children are reported to suffer from asthma in New Zealand.
Good insulation, working extractor fans, good heating throughout the home and secure windows that open are important, Dr Shorter said.
Frequent checks should be made for mould, she said.
"We need to reduce moisture in our homes by not drying clothes inside, and opening windows often to improve ventilation, even for just 10 minutes a day."