An investigation is underway at Christchurch hospital into whether patients, staff and workers have been exposed to white asbestos.
The Ministry of Business, Innovation and Employment began the investigation after receiving a complaint from industrial abseiler workers about possible exposure.
The hospital roof was being repaired when asbestos was uncovered.
Chemsafety, a chemical risk management firm, tested the roof's bitumen and confirmed high levels of white asbestos.
The investigation is expected to take several months.