Tourists injured in the eruption of New Zealand’s White Island/Whakaari volcano have burned lungs from inhaling sulphur dioxide and volcanic ash, and “very significant” deep-tissue burns, some to more than half of their body, a senior emergency doctor has said.

The Australasian College of Emergency Medicine president, Dr John Bonning, was working in the emergency department of Waikato hospital, one of four hospitals in New Zealand with a regional burns unit, when patients arrived from Whakatane and Tauranga hospitals on Monday.

He said patients had severe burns to their skin from hot gas, ash and debris from the volcano, as well as “quite severe” inhalation burns from sulphur dioxide, methane and other chemicals.

“Some of the patients will have significant damage to their lungs. They are very, very ill indeed.”

Bonning said victims also had “full thickness burns in significant parts of the body, in some cases 50% or more, requiring significant surgery and skin grafts and all sorts of other supports”.

“Presuming they get to recovery, this is going to take months to years to recover from, with significant scarring and possible loss of function.”

Twenty-seven of the 31 people injured in the eruption of the Whakaari/White Island volcano had burns to more than 30% of their body and many had inhalation burns, New Zealand’s chief medical officer, Dr Pete Watson, said.

Six people are confirmed to have died, and eight are missing and presumed dead. The injured are aged between 13 and 72 and most were visitors to New Zealand.

Watson said the disaster had stretched the country’s burns units to capacity, with patients spread across the regional burns units in Christchurch, Waikato, Hutt Valley and Auckland’s Middlemore hospital.

“It’s important not to underestimate the gravity of the injuries suffered, the huge response being mounted by our hospitals, and the time it will take for some patients to fully recover,” Watson said. “The volume of work facing our national burns unit at Middlemore hospital in one day is equivalent to the normal workload they would see in a typical year in the burns unit.”

Watson said patients from Australia would be transferred to Australian hospitals once they were stable, to free up local resources and allow them to recover nearer to their loved ones.

Burn units at Australian hospitals have already received calls from New Zealand authorities asking how much capacity they have to take on additional patients. The New South Wales Agency for Clinical Innovation’s Severe Burn Injury Service was contacted on Tuesday, said Associate Professor Peter Haertsch, a specialist plastic and reconstructive surgeon.

“Transferring severely injured people internationally is fraught with difficulty and danger, particularly when we are talking about severe inhalation injury,” he said.

Bonning said it could take weeks for patients to be stable enough to be transferred.

He praised the work of New Zealand’s emergency services, emergency department staff and specialist burns staff.

Siobhan Connolly, the burn-prevention education manager from the Statewide Burn Injury Service, said surgery was “just the beginning” of burn recovery.

“The scar activity is generally most acute in the first two years after the burn, so it can take two years to manage it,” she said. “If it’s a really severe burn, it can affect the survivor for the rest of their life.”

Connolly said all burn units had allied health teams including physiotherapists, occupational therapists, speech therapists, social workers and psychologists to help with patient recovery.

She said the disaster protocol for burns patients recommends they be treated in a hospital near their home whenever possible, but they would not be moved until they were stabilised.

“The good news is New Zealand is a high-quality burn hospital area, so they will have had good treatment very quickly.”

