Hunter Valley

A case study examining air quality at monitoring stations nearby industrial activities in the Hunter Valley. While data from stations near pollution sources are not assessed for compliance with national standards, such comparisons are made available in this statement due to public interest.

The NSW Government maintains 20 air quality monitoring stations in the Hunter Valley, including 3 government-funded stations in the Lower Hunter, 3 industry-funded stations around the port of Newcastle, one mixed industry and government-funded, as well as 13 industry-funded stations in the Upper Hunter.

The government-operated, industry-funded Upper Hunter and Newcastle Local air quality monitoring networks were established in 2011 and 2014, respectively, to monitor local industrial and other pollution sources. Due to the proximity of industrial sources, compliance reporting against the national ambient air quality standards is not applied at these monitoring stations. The exceptions are the Upper Hunter large population centre stations at Muswellbrook, Singleton and Aberdeen, which have been reported for compliance purposes since 2020.

However, the government recognises the community's interest in knowing how air pollution levels at these stations compare against the standards. Therefore, this section refers to national standards as national benchmarks when evaluating air quality data throughout the Hunter Valley.

More information on these networks can be found on our website, including seasonal newsletters and air quality monitoring reports.

Hunter large population centres

  • Upper Hunter – Aberdeen, Singleton and Muswellbrook
  • Lower Hunter – Beresfield, Newcastle and Wallsend
  • Newcastle Local – Carrington, Mayfield and Stockton

Gaseous pollutants

Ozone (O3) and nitrogen dioxide (NO2) met the relevant national benchmarks in the Upper and Lower Hunter regions, including the Newcastle Local network, during 2021. The 1-hour sulfur dioxide SO2 benchmark of 10 pphm was exceeded for one hour in 2021. This was a 1-hour average SO2 level of 12.3 pphm, recorded at Muswellbrook in the Upper Hunter on 4 February 2021.

In 2020, there were 2 days with 1-hour SO2 levels above the (new NEPM) standard, both at Muswellbrook. There were no days over the O3, NO2 or daily SO2 benchmarks in the Hunter Valley.

PM10 particles

Within the Hunter Valley, PM10 levels generally are highest at Stockton in the Newcastle port area due to the influence of sea salt under onshore winds (Lower Hunter Particle Characterisation Study). (Refer to the Stockton tab for more information.) In the Upper Hunter region, PM10 levels generally are highest at stations closest to mining activity.

Annual averages

In 2021, annual average PM10 levels exceeded the 25 µg/m3 benchmark only at Stockton (one of 9 stations in larger population centres). Annual averages ranged from 12.9 µg/m3 at Aberdeen to 30.1 µg/m3 at Stockton.

Daily averages

Daily average PM10 levels exceeded the benchmark at one or more stations in large population centres (excluding Stockton) on one day. This occurred on 29 October 2021 at Singleton in the Upper Hunter and Carrington and Stockton in Newcastle, due to long-range dust transport.

At Stockton, the daily PM10 average was over the benchmark on 24 days and was predominantly affected by sea salt under onshore air flows. Refer to the Stockton tab for more information.

The maximum daily PM10 average recorded in the Hunter population centres occurred at Stockton on 29 October 2021 with a level of 64.2 µg/m3 and was primarily caused by a widespread dust storm. Excluding Stockton, the maximum daily PM10 level in the Hunter population centres occurred at Singleton on the same day with a level of 58.2 µg/m3.

PM2.5 particles

Annual averages

Annual average PM2.5 levels exceeded the 8 µg/m3 benchmark at Stockton in 2021, one of 8 stations measuring PM2.5 in the Hunter's large population centres (PM2.5 is not currently recorded at Aberdeen). Annual averages ranged from 5.9 µg/m3 at Beresfield to 8.3 µg/m3 at Stockton.

Daily averages

There were no daily average PM2.5 levels recorded over the benchmark at any of the Hunter Valley monitoring stations in 2021 (compared with 13 days in 2020).

The maximum daily average PM2.5 level was 21.4 µg/m3, recorded at Wallsend on 15 August 2021. This was due to planned hazard reduction burns in the Greater Metropolitan Region.

The Upper Hunter air quality monitoring network comprises 14 stations – 3 stations in larger population centres, 6 stations in smaller communities, 3 diagnostic stations close to mining operations and 2 background stations at the north-west and south-east extents of the region.

Annual averages

All monitoring stations in the Upper Hunter recorded annual average PM10 levels below the 25 µg/m3 benchmark. PM10 annual averages in the Upper Hunter ranged from 11.7 µg/m3 at Merriwa to 20.8 µg/m3 at Warkworth.

The highest annual average PM10 levels occurred at stations closer to mines; Warkworth (20.8 µg/m3) and Camberwell (20.6 µg/m3), followed by Mt Thorley (19.0 µg/m3). Since 2011, these were the lowest annual PM10 concentrations recorded at 12 of the 14 stations, a result of the wetter conditions across the state and particularly in the Hunter, resulting in lower levels of windswept dust from all sources.

All of the of 4 stations monitoring PM2.5 in the Upper Hunter (Muswellbrook, Singleton, Camberwell and Merriwa) recorded annual average PM2.5 levels below the 8 µg/m3 benchmark. This is the first year that Muswellbrook, which is generally impacted by smoke from residential wood heaters during cooler months, has experienced an annual average PM2.5 level below the current standard of 8 µg/m3 since monitoring began in December 2010.

Daily averages

The Upper Hunter recorded 6 days with daily average PM10 levels over the benchmark at one or more stations, compared to 35 days in 2020.

Days over the daily PM10 benchmark in 2021

Date Number of monitors over benchmark
15/04/2021 1
12/09/2021 3
24/09/2021 1
07/10/2021 3
10/10/2021 3
29/10/2021 7

Mount Thorley recorded the highest number of days over the PM10 daily benchmark in the region, with a total of 5 days, compared to 18 days at Camberwell in 2020.

The highest daily average PM10 level of 82 µg/m3 occurred at Warkworth on 29 October 2021, during a widespread dust storm under north-westerly winds. Six other Upper Hunter monitors were also impacted on this day, as well as two in Newcastle, one in North West Sydney and one in the Illawarra.

Figure 1 Summary of PM10 observations in the Upper Hunter in 2021

Bar chart showing the maximum daily average, annual average and exceptional and non-exceptional event days for PM10 for each of the 14 stations in the Upper Hunter.

Note: Exceedance days have not been divided into exceptional and non-exceptional events, as the NEPM compliance goals are not applied to smaller community, diagnostic or background stations.