For more than seven months Housing NZ knew its tenants were in flats filled with dangerous mould spores.
The spores, up to 30 times the acceptable level, were found inside the Britomart St flats, in the Wellington suburb of Berhampore, a report obtained under the Official Information Act shows.
They included "black mould", which has been linked to possible infant death.
Until yesterday - 11 months after getting the report - Housing NZ property services manager Marcus Bosch said he understood the readings were from inside a wall cavity, not inside a room.
The agency confirmed yesterday that this was not the case and the spores were found in rooms.
In August last year, the report alerted Housing NZ to "unusual and unacceptable" levels of spores in the leaky building.
In January, tenants were given 90 days to vacate, though they were notified of issues earlier. The flats were fully vacated in April.
Rongotai MP Annette King asked why it took more than seven months to move tenants out.
"They move very fast when they want to but it's inexplicable why they would wait so long when they knew there was a problem."
A Housing NZ spokeswoman said stachybotrys - sometimes called black mould - spores were found in a lounge at "low levels".
"This fungus is not desirable in indoor air, and is usually only found when there has been a prolonged leak somewhere in the vicinity of the sampling.
"Although this fungus is considered a toxigenic fungus, this spore level would be unlikely to result in health issues. If, however, the level should increase, there could be resulting health problems."
One mother was moved out early after her doctor provided proof the unit was affecting her children's health.
"We are not aware of any other tenants raising health issues with us due to the unit."
Tenant Carolyn Morgan, who long battled with Housing NZ to fix leaks in her flat and then won a Tenancy Tribunal case which ordered the work, has now moved to Wellington City Council flats.
"I used to constantly get boils," she said. "I haven't got them like I used to."
The Britomart complex had housed elderly people and young families, including a young asthmatic girl, she said.
Mr Bosch said the wait from August, when Housing NZ got the report, to January, when people were given 90 days to vacate, was spent looking at options and in discussions with tenants.
Housing NZ took its tenants' wellbeing "very seriously".
He acknowledged "in hindsight" that Housing NZ could have acted faster.
Mr Bosch could not comment on whether the agency worked to minimise dampness after the report, or whether it had asked tenants about their health.
The buildings were being renovated, he said.
Landcare Research mould specialist Eric McKenzie said black mould had been linked to the deaths of some babies in the United States about 20 years ago.
While there was little evidence to support this, "there's probably some truth to the sickness attributed to it", he said.
The mould contained toxins that led to breathing problems and eye, nose and throat irritation.
The report found 20 parts of black mould per cubic metre of air in the flat. No parts are considered acceptable indoors.
Four of the other spore types found were generally not harmful.
However, those who suffered mould allergies could experience breathing problems from inhaling them. The less harmful spores were between 2.6 and 30 times acceptable levels.
Wellington Mayor Celia Wade-Brown said the council was upgrading its social housing.
- The Dominion Post