Lower Hunter air quality studies

The EPA initiated the Lower Hunter Particle Characterisation Study in 2013 to study the composition of

• airborne particles 2.5 micrometres and smaller in diameter (PM_2.5) in the Lower Hunter region
• particles between 2.5 and 10 micrometres in diameter (PM_2.5-10) near Newcastle Port

The study provides the NSW Government and communities in the Lower Hunter with scientific information about the composition and likely sources of fine particles, invisible to the eye, in the local environment.

The study was a collaboration between the EPA, Office of Environment and Heritage (OEH), the Commonwealth Scientific and Industrial Research Organisation (CSIRO) and the Australian Nuclear Science and Technology Organisation (ANSTO).

The study found that

• PM_2.5 levels and source components were similar at Newcastle, Mayfield and Wallsend
• the annual average level at Stockton was 40% higher than other sites, due to the presence of ammonium nitrate from industry and more sea salt from onshore winds
• PM_2.5-10 levels were 2.5 times higher at Stockton than Mayfield, mainly due to more fresh sea salt
• PM_2.5-10 particles contained about 10% carbon at Mayfield and Stockton, some of which may have been coal particles

Likely sources for PM_2.5 at all four sites included

• fresh sea salt (13-24%)
• pollutant-aged sea salt (23%)
• wood smoke (6-15%)
• soil dust (10%)
• secondary ammonium sulfate from industry (10%)
• vehicles (10%, and 5% at Stockton)
• industry (13%, and 24% at Stockton)
• shipping and mixed industry (3%)

Likely source components for PM_2.5-10 at Mayfield and Stockton were

• fresh sea salt (13.6–3.3 µg m^-3)
• pollutant-aged sea salt and industry (2.4 µg m^-3)
• carbon (2.2–0.8 µg m^-3), potentially containing coal
• soil dust (2.3–1.2 µg m^-3)
• bioaerosol (fungal spores) (1.1–0.5 µg m^-3)

The Lower Hunter Particle Characterisation Study: Final report (PDF 17.8MB) and appendices (PDF 3.2MB) provide a full analysis and interpretation of the data collected during this study.

Our Local Air Quality: Findings from the Lower Hunter Particle Characterisation Study (PDF 939KB) provides a summary of the findings.

The Chemical Transport Modelling Case Studies Report (PDF 6MB) established the validity of the Lower Hunter air model. The case studied

• estimated PM_2.5 concentrations and components in July and November 2014
• provided snapshots of pollution in the region for the periods modelled

The studies found that the levels and composition of fine particles across the region, including at Lake Macquarie and Maitland, were similar to levels measured at the study sites around the port of Newcastle. This finding was the consistent with the nature of fine particles that stay suspended for long periods, travel long distances and mix well in the air.

Lower Hunter residents were concerned about the levels of visible black dust in the lower Hunter region. The EPA commissioned a study to examine the quantity, composition and likely sources of deposited dust. To ensure that the views of the community were fully considered, the EPA established a project reference group.

Key findings included

• dust deposition rates ranged from 0.5 to 1.1 grams per square metre per month (g/m²/month) and were below the EPA’s annual criterion of 4 g/m²/month
• dust particle composition in the 12 dust deposition samples comprised 17% black particles, contributing 0.09 to 0.19 g/m²/month to annual average dust composition
• coal would contribute 0.05 to 0.11 g/m²/month to annual average dust composition

Laboratory analysis revealed that the samples, visible to the eye as black dust, were comprised of

• brown particles of soil or rock
• black particles of coal, soot and rubber
• lighter coloured particles of salt, ash, plant and insect debris, alumina and paint

Dust particle composition in 72 samples averaged

• 69% soil, ranging from 40% to 90%
• 10% coal, ranging from 0% to 25 %
• 4% rubber, ranging from 0% to 20%
• 3% soot, ranging from 0% to 20%
• 14% other components, including salt, ash, insect and plant debris, alumina and paint

The Lower Hunter Dust Deposition Final Report (PDF 2MB) details sampling, analysis and results from the Dust Deposition study.

Appendices A to E (PDF 6.3MB) include a community flyer inviting residents to host sampling sites, meteorological data, wind conditions during sampling periods, fieldwork records and laboratory certificates for dust gauge analyses.

Appendices F and G (PDF 8.4MB): contain laboratory microscopy reports and a summary of stereomicroscopy results for dust gauge, Petri dish and brush samples.