Health workers have described how "dangerous levels" of short-staffing across the country's hospitals is putting patients and staff at risk.

Nearly 700 people working for district health boards responded to a PSA union survey about the effects of short-staffing and unfilled vacancies in their areas of work.

The survey asked staff from more than 130 occupations in allied, public health and technical occupations including physiotherapists, anaesthetic technicians and social workers.

The survey report said responses revealed pervasive and "dangerous" levels of understaffing, with ongoing consequences for both patients and workers.

"The length of time people spend waiting for services means people become more acutely unwell or are left with permanent injury and chronic conditions that limit their quality of life," the report said.

One survey respondent, an anaesthetic technician, said "we are absolutely, critically, and dangerously short of staff in the acute operating theatres. Patients lives are more frequently at risk because of dangerous level of understaffing".

A dental therapist said they sometimes see patients two to three years apart instead of annually, while a sterile supply worker said understaffing means the team has to rush through work "with the potential for accidents".

PSA national organiser for DHBs Sue McCullough said short-staffing at district health boards was compromising patient care.

She said health workers had been struggling for a while but it was getting to the point where they really did not feel they could give any more.

"The short staffing means people are doing extra work, extra overtime, for free," said Ms McCullough.

"What it means is that people aren't getting the best treatment that they can. If that's in a physio service it means acute patients are bumped down the list so that the more acute patients, the respiratory patients, will be seen but perhaps the knee or back injuries won't be seen as quickly and then things deteriorate. It has a knock-on effect."

Next week Allied health PSA members will vote on whether to accept a minimum pay rise of 9 percent.