But the police union believes the medical discharge of officers can be prevented if more funding is provided to officers' Workplace Improvement Program.

Police Association of NSW Orange branch chairman Adam Piffarelli said 22 officers were discharged last month due to psychological injury and 95 per cent of the discharges were due to Post-Traumatic Stress Disorder.

"This [PTSD] affects every officer, including those in Orange and the Central West Police District," Mr Piffarelli said. 

"This is not something that's unique to the city cops, but it's something that affects cops everywhere."

The Police Association of NSW said half of the injured officers are city-based and the other half are from regional areas despite the fact that more officers are based in metropolitan areas.

Its secretary Pat Gooley said these figures are alarming, but not surprising.

"There's no doubt we've got a mental health emergency among police in NSW," Mr Gooley said.

"What's surprising is that governments continue to ignore the problem rather than taking action to address it.

"We're losing 300 highly trained, skilled police officers from the force every year - you'd think that would be cause for action."

The police association said the Workplace Improvement Program had proven to help officers with their physical and mental wellbeing, but it was not available to everyone because of the lack of government investment.

"The NSW government hasn't allocated the funds to have it rolled out throughout the state so that everyone - no matter where they're located - can have access to the support," Mr Gooley said.

"The NSW opposition has committed to doubling the funding available for the Workplace Improvement Program, which is fantastic, but police shouldn't need a change of government to ensure that we're given the support we need and deserve."