Further evidence of a link between overloaded health systems and higher police callouts.

Official documents show from 2018 to 2022 police callouts to health locations like hospitals and medical centres tend to peak in the early afternoon, when nurses say EDs are filling up.

It comes after Newstalk ZB revealed callouts for harassment and threatening behaviour in these settings has nearly doubled in four years.

NZNO President Anne Daniels says this shows how increased wait times fuel the abuse, as patients begin to arrive at about 10am.

"If you have 10 people coming in at 10am and then 11am and 12pm instead of just having 10 patients in the ED, and then by 3pm, you've got 50 patients. And you've still got the same number of hospital beds."

National's Shane Reti says it makes sense crime's higher when health settings are under stress, and he agrees with healthcare workers.

"There's highly likely to be a relationship through emergency department wait times, particularly with the figures that we're seeing."

Shane Reti also says healthcare workers feel less safe when hospitals are full.

"They're concerned about their risk returning to their vehicles particularly, and that's worse when the hospital's under stress just because there's more people out."

Te Whatu Ora Health New Zealand's identified workplace violence as a critical risk, as official documents show a rise in crime.

Hospital and Specialist services director Fionnagh Dougan says staff have a right to feel safe, and work underway includes training in de-escalation and providing staff to support care.

They've also implemented a national project group to work on the issue.