About 36,000 nurses, midwives and healthcare assistants are walking off the job for eight hours today over what they say are critical threats to patient safety.

Nurses Organisation chief executive Paul Goulter said collective bargaining had stalled over "the big ticket items", which centred on patient safety.

Union members were particularly worried about Health New Zealand's plan to pause the Care Capacity Demand Management programme, he said.

That calculates the number of staff and the skill mix needed to safely care for patients according to how sick they are, in real time.

"Ultimately, patients will pay the price for hospitals that are continuously understaffed and under-resourced," Goulter said.

Members were also disappointed with Te Whatu Ora restricting "bargaining parameters" for the settlement to 1 percent of total employee costs.

This would equate to just 0.5 percent in the first year, and up to 1 percent in the second year.

"This means nurses, midwives, health care assistants and kaimahi hauora will be offered a wage increase well below the rate of inflation - and effectively a pay cut. Nurses should not have to prop up the health system by taking cuts in pay," Goulter said.

"This could lead to a further exodus of New Zealand nurses to Australia. Nurses need a pay rise that reflects at least the cost of living and recognises their skills and knowledge."

Cost-cutting hurting patient care, nurses say

Waikato nurse Tracy Chisholm said the "lack of respect" by management and the government for nurses "needs to be called out".

"For me it's about safety - the safety of our patients. How do we provide culturally safe care without the nurses to do it; how do we educate, prevent deterioration and further harm without the nurses to provide; how do we meet the governments health Kaupapa without the nurses?"

Rotorua nurse Lyn Logan said Te Whatu Ora's constant financial constraints were impacting patient care.

"When we are under-resourced and understaffed, we do not have enough healthcare workers to give the best care, and our patient's care will suffer as a result.

"For me, it's about informing the public who use health services, and my community, that if I do not strike then I am not committed to improving health services in my region. I want to give our community the best care I can when they come into the hospital, at present I cannot do this."

Christchurch nurse Debbie Handisides said she was striking for future nurses and patients.

"We have fought for years for nurses to be paid equally to a male comparator, but with the parameters that Te Whatu Ora are proposing up to 1 percent total cost of a nurse won't even meet the household cost of living, so why would anyone pick nursing as a career if they can't pay their household bills?"

Plans in place - Health NZ

Health New Zealand said hospitals and emergency departments would remain open during the strike action.

Deputy chief executive Northern Mark Shepherd said to "maintain patient safety", some clinics would be closed.

"However, if you have a hospital appointment tomorrow (Tuesday), please come to your appointment unless we have contacted you directly to reschedule.

"Any appointments that are deferred due to the strike action will be rescheduled for the next available opportunity."

A patient with an outpatient appointment at Wellington Hospital said she was only informed on Monday that it had been cancelled and rebooked for February.

Shepherd said Health NZ valued the contribution of its nursing workforce - but was "disappointed that strike action is being taken so early in the bargaining process".

"We are committed to reaching a settlement with NZNO. Any settlement needs to reflect the ongoing reset of Health NZ as we work to get back to budget and complete the restructuring underway. "

Shepherd said nurses' salaries had "outperformed the broader labour market outcomes" in recent years, with pay rates for mid career nurses rising by 28 percent since 2016, plus additional 23 percent from the recent pay equity settlement.

But Goulter said it was misleading to include the pay equity settlement, which was meant to compensate nurses for historic sex-based discrimination.

"Te Whatu Ora has completely failed to recognise that you can't conflate that with nurses' legitimate request to receive at least the cost of living movement as well as recognising the value they bring to their work.

"I think in a way it's quite insulting."

-RNZ