Asbestos hazard in Christchurch CBD
The Government is working to contain hazardous asbestos after a central Christchurch street was contaminated by the potentially harmful material.
Loose asbestos fibres from the demolition of BNZ House in Cathedral Square were found in Hereford St and a nearby red-zone site where rubble from the building is being stockpiled.
White and brown asbestos were found at five points in Hereford St and nine points on the stockpile site, says a report commissioned by the Canterbury Earthquake Recovery Authority (Cera), which is managing the demolition.
Government agencies and the demolition contractor for BNZ House were working "to ensure any hazardous material at the stockpile area is covered and contained to remove any risk to the public", a Cera spokesman said.
A minute amount of asbestos was found in the street, he said.
"Testing found some trace elements in surrounding work areas," he said. "The hazardous materials were removed and subsequent testing for asbestos returned negative results."
Cera said it had no evidence any asbestos fibres had been released into the atmosphere during demolition of BNZ House.
Asbestos was found at the Cathedral Square site in late July, and demolition work has been on hold since.
The 13-storey building was being brought down by high-reach excavators, but the asbestos discovery means sections of the building will now be cut apart and craned away.
All work on the building stopped for about five weeks after the asbestos discovery, and then specialists in full protective gear started scrubbing the noxious material from steel columns.
Canterbury medical officer of health Alistair Humphrey said asbestos was harmful only if a person was exposed to high levels of the material during a long period.
"If you look at our data, more than 99 per cent of asbestos-related diseases have been due to occupational exposure. It is relatively high exposure over long periods of time," he said.
"There is a background level of asbestos everywhere. Road junctions at traffic lights have higher levels of asbestos because older cars have asbestos in their brakes.
"The real issue is whether this reaches a level that is likely to cause a health issue. I couldn't comment on that."
The Ministry of Business, Innovation and Employment was notified of the BNZ House asbestos discovery on August 7.
The main contractor, Hawkins, provided the ministry with a report on the discovery.
The report included air-monitoring information that showed "levels of asbestos fibre were below the workplace exposure standard", a ministry spokeswoman said.
"We were satisfied from reading the main contractor's report into the discovery that all reasonable steps had been taken to identify, control and manage the ongoing work," she said.
A Cera spokesman said asbestos had been found at other Christchurch sites.
"While all relevant parties are notified wherever asbestos is found in a demolition, Cera has no central register recording the total notifications," she said.
- A mineral once used in construction.
- Prolonged, chronic exposure to asbestos can lead to the development of various lung diseases, including asbestosis and a form of lung cancer know as mesothelioma.
- It can take many decades after exposure for lung cancer to develop.
- Blue and brown asbestos are considered more harmful than white asbestos, but most cases of asbestos-related disease in New Zealand are from white asbestos because it was more widely used.
- The import of blue and brown asbestos was banned in New Zealand in 1984 and the import of white asbestos was banned in 2002.