A NSW government plan for ambulance superstations has been criticised as "a recipe for disaster" as new documents reveal existing stations will be downgraded.
More than a dozen stations including those across Sydney's eastern and western suburbs will be converted to `standby points' according to a NSW Ambulance map of the new Paramedic Response Network.
NSW Ambulance says the operating model will deliver a more even deployment of paramedics across the city.
But the Health Services Union (HSU) says it fears response times will weaken in areas furthest away from the superstations.
"The new ambulance superstations will suck paramedics out of their communities and concentrate them in larger centres," HSU NSW secretary Gerard Hayes said on Thursday.
"Particularly at shift start and finish times of 7am and 7pm, response times will blow out," he said.
Mr Hayes also raised concerns about the on-ground presence of paramedics in areas that will see local ambulance stations downsized over the next 18 months, and is pushing for an additional 800 paramedics to be deployed across the state.
A similar network implemented in the United Kingdom was unsuccessful and put patient safety at risk, NSW opposition health spokesman Walt Secord said.
"It resulted in longer waits for an ambulance and patients having to be transported greater distances. That is a recipe for disaster," he said in a statement.
The NSW Ambulance director of the program, Clare Beech, said the innovative, evidence-based model had been designed to reduce the likelihood of lengthy responses for patients needing emergency paramedic care.
"Currently there are 47 facilities which NSW Ambulance paramedics respond to patients from across metropolitan Sydney," Ms Beech said.
"Once the Paramedic Response Network is fully operational there will be more NSW Ambulance facilities across metropolitan Sydney than currently exist within this response area," she said.
