Lower Hunter Particle Characterisation Study

Learn more about the findings from the scientific study investigating the sources of particle pollution in the Lower Hunter.

The Lower Hunter Particle Characterisation Study was commissioned by the NSW Environment Protection Authority in 2013 to investigate the composition and major sources of particle pollution in the Lower Hunter. The study was conducted by scientists from the Office of Environment and Heritage (OEH), CSIRO and the Australian Nuclear Science and Technology Organisation (ANSTO), with oversight from the NSW Ministry of Health, and completed in 2016.

Focusing on very small particles, invisible to the human eye, which can be inhaled and can pass through the throat and nose and into the lungs, the study aimed to determine the composition and major sources of fine particles (PM2.5) and coarse particles (PM2.5-10).

Fine particles were monitored at four sites, including two sites representative of regional population exposures (Newcastle, Beresfield) and two sites near the Port of Newcastle (Mayfield and Stockton). Coarse particles were monitored at Mayfield and Stockton, the two sites near the Port of Newcastle.

What did the study find out about fine particles?

Annual average fine particle concentrations were very similar at Newcastle, Mayfield and Beresfield (6.4–6.7 micrograms per cubic metre or µg m-3) but about 40% higher at Stockton (9.1 µg m-3). The higher levels at Stockton were mainly due to more sea salt and primary ammonium nitrate. Ammonium nitrate contributed on average 19% of the fine particle mass at Stockton (and 40% in winter), and was most likely due to emissions from the ammonium nitrate manufacturing facility on Kooragang Island.

Other than the ammonium nitrate, fine particle composition and sources were found to be fairly similar across the four sites.

The source factors and their contributions to fine particles over the year were:

  • fresh sea salt particles: 24% at Newcastle, decreasing to 13% at Beresfield
  • pollutant-aged sea salt: about 23% at all sites; this is sea salt reacted with industrial, commercial, road and non-road transport emissions from local and regional sources
  • wood smoke: 15% at Beresfield, decreasing to 6% at Stockton
  • secondary ammonium sulfate: about 10% at all sites
  • soil dust: about 10% at all sites
  • vehicles: about 10% at three sites, and about 5% at Stockton
  • industry factors: about 12% at three sites and 24% at Stockton
  • mixed shipping and industry: about 3% at all sites
  • nitrate: 19% ammonium nitrate at Stockton and secondary nitrate at other sites (6-11%).

On an annual average basis, there is an approximately 50:50 split between primary and secondary particles at three sites (Newcastle, Beresfield and Mayfield) and a 65:35 split at Stockton because of the significant contribution from the primary ammonium nitrate.

What did the study find out about coarse particles?

Coarse particle composition and sources were determined at the sites near the Port of Newcastle. The annual average coarse particle concentration was two and a half times higher at Stockton (21.5 µg m-3) compared to Mayfield (8.3 µg m-3), mainly due to fresh sea salt.

The source factors and their contributions to coarse particles over the year were:

  • fresh sea salt: 13.6 µg m-3 at Stockton, 3.3 µg m-3 at Mayfield
  • industry plus pollutant-aged sea salt: 2.4 µg m-3 at both sites
  • light-absorbing carbon: 2.2 µg m-3 at Stockton, 0.9 µg m-3 at Mayfield
  • soil: 2.3 µg m-3 at Stockton, 1.2 µg m-3 at Mayfield
  • bioaerosols: 1.1 µg m-3 at Stockton, 0.5 µg m-3 at Mayfield.

Most coarse particles are primary particles or physical combinations of primary emissions, but there is evidence of chemical reactions in the pollutant-aged sea salt factor.

Light-absorbing carbon was found to account for about 10% of the coarse particle mass at Mayfield and Stockton. Coal particles could contribute to light absorbing carbon, and so contribute up to 10% of the coarse particles.

What does chemical transport modelling tell us?

In addition to the main study, computer modelling was used to understand the distribution of particles over the broader region. This chemical transport modelling confirmed that the levels and composition of fine particles across the region, including at Lake Macquarie and Maitland, are similar to those at the sites studied. This is because fine particles stay in the air for long periods and can travel long distances.

How will the results of this study be used?

This study provides a better understanding of the composition and sources of particle pollution in the Lower Hunter. The results from this study contribute to the evidence base that the NSW Government relies on to inform policies and programs to reduce particle air pollution.

What are the health impacts of fine particles?

Exposure to fine particles (PM2.5) is a significant health concern because they can pass through the throat and nose and enter deep into the lungs, where they can cause respiratory and circulation problems, particularly in elderly people, children and people with existing health conditions. There is also emerging evidence that exposure to coarse particles (PM2.5-10) may cause an increase in cardiovascular and respiratory health effects.

According to the World Health Organization (WHO), particulate matter affects more people than any other pollutant, and its effects on health occur at levels of exposure currently being experienced by most urban and rural populations in developed countries (see WHO, Air quality and health fact sheet).

Progress reports and consultations

Before the commencement of the study, the EPA consulted with the Newcastle community on 13 August 2013 about the scope of the study. The NCCCE nominated a representative to the study management team to provide further opportunities for community inputs into the study design and implementation.

A series of progress reports were published during the study to provide updates on the study status.

The study findings were presented at a community briefing on 27 April 2016 at the Newcastle City Hall.

Related sites

Page last updated: 28 April 2016