Workers complaining of asbestos exposure in Canterbury have increased by 350 per cent following the Christchurch earthquakes.
But with asbestos not covered by health and safety notification laws, companies are not obligated to report it, and the scope of the problem may be much larger.
In the last two years, government workplace health and safety regulator Worksafe has shut down the sites of Christchurch companies with 33 prohibition notices for unsafe asbestos removal.
Worksafe Canterbury rebuild health and safety director Kathryn Heiler said that, despite increasing training and awareness, companies were still demolishing buildings without checking for asbestos.
"Our inspectors are seeing too many properties throughout the region being demolished before asbestos has been properly identified and appropriate controls have been put in place," she said. "This is simply not acceptable."
Complaints to Worksafe of asbestos exposure jumped from 16 in 2010 to more than 70 last year, a 350 per cent increase.
And notifications of being exposed unsafely to asbestos recorded on the voluntary National Asbestos Register have tripled from pre-quake levels to 61.
Data collected by Ministry of Business, Innovation and Employment shows a huge amount of asbestos work being done in Christchurch. They record 560 notifications of asbestos work from July 2012 to May 2013 - compared to 48 in Auckland and 40 in Wellington.
Asbestos was a common building material in Kiwi homes until its carcinogenic properties were discovered in the 1980s.
Enclosed and undisturbed, it is benign, but as post-quake deconstruction ramps up some demolition companies are not testing for the substance properly.
A demolition worker speaking to The Press anonymously said when he first began in demolition in 2013, the company did not test for asbestos, wear safety gear or have safety procedures for dealing with the substance.
"We had nothing. It wasn't talked about at all. Asbestos was like this sort of myth. We weren't testing the buildings we demolished."
He estimates around half the houses they demolished in that time period could have been asbestos contaminated.
"Only now, looking back, in hindsight . . . pretty much everything we touched could have had asbestos in it."
At the end of 2013 company training began, and safety procedures were put in place, and the team realised how much exposure they may have already had.
"It was a big shock. Most people felt pretty depressed. Even our foreman was like ‘Oh, my God,' because he'd been doing demolition for two years, pulling down buildings and breathing this stuff in."
He had not laid a complaint or registered on the exposure registry, and believed many others would not bother.
A Worksafe spokesperson said employers were not obligated to report if employees were exposed to asbestos.
Asbestos exposure was not included in the legislation criteria and could not be recorded as a serious harm notification.
Worksafe had issued 33 prohibition notices to 25 companies since 2012 for asbestos, including Wheelers Construction.
Wheelers office manager Suzy Bragg said initially there were no clear guidelines for asbestos removal in residential homes.
"When we first started [after the earthquakes], no-one really knew what the asbestos requirements were.
"It wasn't till the end of 2012 that anyone even started thinking about asbestos."
Bragg said Wheelers followed all legal requirements as they learned of them. She said the company had responded to each of their two Worksafe prohibition notices and fixed the problem within 24 hours.
University of Canterbury Toxicology Professor Ian Shaw said health effects from asbestos would only emerge years after exposure.
He said high exposure over several years was needed for serious effects to be likely, but there was no "minimum exposure" to cause cancer.
"In theory you only need one asbestos fibre, and for that fibre get into the right place into the lungs."
- The Press