Prof Philippa Howden-Chapman, of Wellington, said the issue of mould and damp in homes was costing the country an estimated $300 million to $500 million a year.
Mould in homes was a "significant" problem nationally, she said.
There was also evidence that the risk of getting asthma increased by up to 30% in damp homes, and depression had been linked to living in a cold, mouldy home.
Prof Howden-Chapman is in Dunedin to speak at the New Zealand International Science Festival today.
She said homes in the South Island were cold because they were poorly heated, which contributed to health issues, while homes in the North Island were more prone to mould because the conditions suited the growth of mould.
A recent survey of third-year medical student flats in Dunedin showed that one-third had "significant mould", which posed a three-fold risk of those students experiencing wheezing, she said.
Prof Howden-Chapman be-lieved landlords needed to be regulated so that private rental properties reached a certain level in terms of warmth and insulation from damp.
People often "just put up with" cold, damp houses, but in other countries there was proper heating and insulation, which meant people were healthier.
In New Zealand people tended to treat the consequences of a damp house, such as asthma, rather than treating the cause.
Prof Howden-Chapman will speak at the Academy Cinema, Dundas St, at 12.15pm until 1pm.
Keeping the heat
Sustainable and efficient heating:
Modern woodburner/pellet fire.
Heat pump.
Flued gas.
Solutions for mould-free new homes:
Needs to be an increasing awareness of flood-prone or damp areas before building.
Damp-proof a home by making sure it has adequate spouting and drainage.
Insulate.
Maintain the property.
New fashions in building design need to be tested to see whether they are leak-proof.
Install sustainable and efficient heating.
