The latest national pollution data shows several Hunter and Central Coast power stations have reported significant increases in toxic emissions while overall power generation dropped.
Despite a 31 per cent and 9 per cent drop in generation at Liddell and Bayswater respectively, both pumped more pollution into the air in 2020-21 than the year prior, according to new National Pollution Inventory data.
Liddell more than doubled its fine particle (PM2.5) pollution and almost doubled its coarse particle (PM10) pollution from 2019-20.
Bayswater is NSW's highest polluter of nitrogen oxides and mercury reporting an 81 per cent surge in mercury, and emitting four times more mercury than the next highest Eraring.
"AGL is pumping tonnes of toxic chemicals into the air we breathe which cause chronic lung conditions, children to suffer asthma and babies to be born with low birthweight," Environmental Justice Australia Senior Lawyer Charley Brumby-Rendell said.
"While renewables have surged ahead in recent years, clunky coal-burning power stations are producing less power and polluting more compared to output, than they have in the past.
"Air pollution from coal-burning power stations is a serious concern for the health of our community. It is strongly linked to people developing chronic lung conditions, such as asthma," Kincumber GP Dr Ian Charlton said.
"On the Central Coast alone, these pollutants cause an extra 600 cases of childhood asthma and an increase in the number of hospital admissions for people with airways disease."
Nature Conservation Council policy director Dr Brad Smith said coal-fired power stations remained the most polluting industrial facilities in NSW
"All these pollutants have a huge impact on people's health so these facilities must clean up their operations and shut as soon as possible," he said.
An Australian Energy Council spokesperson said its analysis of NPI emissions data for coal-fired power plants showed that over the past five years there has been a fall in oxides of nitrogen , sulphur dioxide , particulate and mercury emissions.
"A range of factors can result in noticeable shifts in emissions, particularly year-on-year, such as demand and availability of plant," the spokesman said.
"Year-on-year variations can occur as a result of variability of individual plant performances. Stakeholders should not be distracted by this noise: the important thing the NPI data shows is that across Australia's coal-fired generation fleet the trendline for emissions continues to go down. This is expected to continue as the energy transition results in a change in the grid's generation mix.