ST MARYS fire station officer Carlos Henry fears government funding cuts mean more homes are at risk.
Mr Henry, who is also senior vice-president of the Fire Brigades' Employees Union, said the loss of even one position could delay an emergency response by five to 10 minutes.
"If your house is on fire or you're trapped in a car, that can make a big difference," he said.
He said every station's minimal strength had to be three firefighters and one station officer but the state government's proposed cuts would slice $70 million of employee-based cost savings from the brigades over four years.
"We feel that will mean 300 fewer jobs," Mr Henry said.
He said any station with fewer than three firefighters would have to close.
He said although St Marys fire station was not likely to be one of them, it could lose some of its other capabilities, such as rescue and hazardous material services.
Mulgoa state MP Tanya Davies said firefighters had the highest level of sick leave among government agencies which had contributed to overtime blowing out to more than $7 million over budget.
She said savings could be made by closing normal station activities for temporary periods.
"Taking fire stations offline is not new; stations may be offline to allow firefighters training, to undertake bushfire hazard reduction or for other activities," Mrs Davies said.
But Mr Henry said taking a station even temporarily offline could mean a fatal delay in responding to a fire.
He said the union had suggested alternative cost-cutting measures, such as allowing long service leave to be taken in small allotments, instead of in bulk.
"We should be employing more firefighters, but I think the government wants to close stations," Mr Henry said.
Mrs Davies said the fire service was interested in discussing alternative measures with the union and had suspended taking stations offline while talks were under way.
"This presents an opportunity to consider options to deliver benefits for firefighters and the community."