Air pollution from NSW's five coal-fired power stations carry a "substantial health burden", including leading to an estimated 279 deaths a year with thousands more to come before they close, a new study has found.

Ben Ewald, a GP and public health lecturer at the University of Newcastle, said the impact – including 233 low-birth weight babies and 369 people developing Type 2 diabetes annually – was much worse than he expected.

AGL's Bayswater coal-fired power station in the Hunter Valley, one of five in NSW that have been tied to health impacts including early deaths. Credit:Glen McCurtayne

"Literally hundreds of people are dying preventable deaths every year because of coal-fired power,” Dr Ewald said, adding, it was "nothing short of a public health scandal" that 3429 more people will die before the plants reach scheduled closure dates.

The study, commissioned by Environmental Justice Australia, examined the effects of fine particle pollution with a diameter of 2.5 microns or smaller emitted by the plants. Coal combustion is one of NSW's biggest sources of such pollution, with prevailing winds often dragging the particles – the smallest of which can enter lungs and the bloodstream – over major population centres.