Mould samples collected by South Auckland school students from some of their own homes have been found to contain health-threatening yeasts as well as antibiotic-resistant bacteria.
That has renewed a call from Mangere Budgeting Service manager Darryl Evans for building warrants of fitness for all rental homes.
Not only were 18 out of 22 students' homes in a study overseen by Landcare Research found to be mouldy, but scientists were alarmed by the discovery of three types of yeast they describe as "emerging human pathogens".
The sampling was prompted partly by a coroner's finding that the poor conditions of a cold and uncarpeted state house contributed to the death last year of a 2-year-old Otara girl from bronchopneumonia.
Rongomai School science teacher and Otara resident Nicholas Pattison came up with an idea for the study, which gained a Government research grant, before students from Manurewa High School were enlisted to gather mould samples for analysis.
Mr Pattison approached Landcare Research plant pathologist Stanley Bellgard to oversee the project, and East Tamaki Healthcare, which gave the students swabs and equipment to measure temperature and humidity.
Mr Bellgard told Radio New Zealand that although moulds tended not to affect healthy people, they created a downward spiral for those predisposed to disease or who were stressed or malnourished.
But he was particularly surprised to find the three types of yeast, which had the potential to cause harm, and also three bacteria resistant to antibiotics.
Mr Pattison said the project was eye-opening for his primary school students, some of whom spent a day at Landcare looking at the mould samples under microscopes before Mr Bellgard presented results to a prizegiving ceremony on Thursday night attended by community leaders as well as the children and their parents.
Care was taken not to identify which homes had mould, or even whether they were state houses or privately owned, especially given a need for co-operation with follow-up research.
But Mr Pattison hoped the project would raise community awareness of the health threat posed by mouldy homes.
The whole idea was to get some data without stigmatising anyone. I think within our community, if people have underlying conditions such as being asthmatic and you have the other moulds present, it's just adding to it. We have lots of kids who have coughs, and wheeze quite persistently.
Mr Evans said he was unsurprised by the amount of mould found by the students, given how much of South Auckland was built on damp swampland and how impoverished many of its residents were, leaving them unable to afford to heat or ventilate their homes.
Although the Government offered "a really generous subsidy" for insulating and ventilating homes, many landlords were reluctant to shell out any amount of money for doing so.
"That's why I have been a strong advocate of getting a building warrant of fitness for every rental home in the country," he said.
"An insulated home warms up so much quicker and for the most part doesn't get mould."