A major study investigating air pollution in the New South Wales Lower Hunter has found chemical giant Orica is contributing to ammonium nitrate levels.

The Environment Protection Authority (EPA) carried out the particle characterisation study and dust deposition study in 2014 and 2015.

Particles were sampled at four sites — Newcastle, Beresfield, Mayfield, and Stockton.

The studies found levels were good overall by world standards, but did spike at times as a result of seasonal weather patterns and industrial activities on nearby Kooragang Island.

The study found sea salt was the largest contributor of fine and coarse inhalable particles.

EPA chief executive Barry Buffier said the higher levels at Stockton were mainly due to sea salt and ammonium nitrate.

"I don't think we had a good understanding of that ammonium nitrate issue in Stockton before we did this study," he said.

"So we've put some pollution reduction programs in at Orica in relation to their operations there.

"We'll have a better idea soon as to how effective that's been."

The study found annual average PM 2.5 concentrations were very similar at Newcastle, Mayfield and Beresfield.

Orica to work on pollution reduction program

More data has been collected from Stockton since the particle characterisation study finished, and Orica is funding further analysis.

Kooragang Island site manager Scott Reid said the company was committed to addressing the matter.

"We'll immediately propose a pollution reduction program with the EPA," he said.

"We'll also fund further analysis of particles from the Stockton station, and we'll continue investigations into technologies that will further reduce ammonium emissions from our site."

Mr Reid said changes had been made to the site, including shutting down a section of the plant.

"We've also modified aspects of the prill tower's operations, that will hopefully minimise a generation of particulates during the cooling process," he said.

"We've reduced the airflow through that prill tower.

"We have replaced some equipment and upgraded some equipment in the plant, and we've also done some tweaking of our chemical processes."

Newcastle industry
Photo: The Environment Protection Authority took particles samples at four sites — Newcastle, Beresfield, Mayfield, and Stockton. (Supplied: J Spencer, NSW Office of Environment and Heritage)
10 per cent of dust particles come from coal

The findings of the dust deposition study found coal made up just 10 per cent of the larger dust particles that were visible to the human eye.

Sample sites were selected on where air pollution complaints had been received.

EPA Hunter manager Adam Gilligan said nearly 70 per cent of the large particles came from soil and rock.

"People often expect that material that appears black on their window sills and the like must be coming from the coal industry," he said.

"To see that coal is actually averaging 10 per cent of that large dust that's deposited is no doubt going to be a surprise to some."

The NSW Minerals Council said the research shows coal dust is a relatively minor source of pollution, contradicting what it describes as 'alarmist rhetoric' on the region's air quality.

But Keith Craig from the Stockton Residents Group said coal dust levels are not insignificant.

"I think that's typical of the Minerals Council, but if you talk to the coal industry themselves they realise you've got to have continuous improvement and do things better," he said.

"I mean, every winter people start complaining about black stuff in their pools and on their houses when you've got those westerly winds, so it's still definitely an issue for the community."

The EPA's dust deposition study
Photo: The findings of the EPA's dust deposition study found coal makes up just 10 per cent of the larger dust particles. (ABC News: Nic MacBean)
Greens continue calls for national air pollution act

Greens candidate for the federal seat of Newcastle John Mackenzie described the studies as a "smoking gun".

"It has revealed the extraordinary contribution to particulate pollution from the Orica operations on Kooragang, and the black carbon particles attributable to the city's coal haulage industry, including the coal terminals," he said.

"This study reinforces the Greens' call for a national Air Pollution Control Act and a Commonwealth regulator, so that this kind of work can be extended to other pollution hotspots around the country."

Dr Mackenzie said he would be campaigning for a nationally-consistent approach to air pollution during the upcoming election.

"The innovative work on particle pollution characterisation is a landmark achievement, and demonstrates the kind of outcomes that are possible when industry, community, and government work together to find solutions to the complex issue of air pollution," he said.

"The Greens will continue to argue for strict and enforceable limits in industry operating licences, where the polluters themselves are financially responsible for the health and environmental costs of their pollution.

"Enforceable limits provide real incentives for ongoing improvements and the adoption of cleaner technologies, and works to bring air pollution back within safe levels of exposure, to the benefit of the entire community."

Newcastle Greens candidate, Dr John Mackenzie
Photo: Greens candidate John Mackenzie described the studies as a "smoking gun". (ABC News: Liz Farquhar)
Opposition and residents call for action

The NSW Opposition's environment spokeswoman Penny Sharpe is calling on the Liberal Government to come up with a management plan to address air quality issues.

Ms Sharpe said she was not surprised by the recent findings.

"It shows that there are increased fine particle matters in the air and around the Hunter," she said.

"Really, there needs to be a plan of action from the EPA, local industry and the community on how you're going to reduce that.

"I'd like to see the EPA sit down with the community, which I know they've been doing, and I'd like them to sit down with Orica and really work through what emissions reductions are happening."

Stockton residents have also urged chemical giant Orica to install better pollution measures.

Keith Craig from the Stockton Residents Action Group said while the chemical giant is already taking action, he would like to see more done to cut fine particle pollution from the plant.

"I think the big one, and some of the most dangerous fine particles, was the 40 per cent contribution from Orica during the winter months, when the winds come from Orica," he said.

"So it really needs action and really the only way to do it is to collect those emissions, and put them through a scrubber to reduce the fine particles.

"That's what the new prill towers are designed to do, they have low emissions."

In 2014, Newcastle residents gathered to hear the results of a community-run survey called 'Dust Free Streets Project'.