Indicator assessment
CONDITION
TREND
DATA QUALITY
With the exception of PM2.5, data on the origins and emissions of diffuse source air pollution has not been updated since 1999 despite contributing the majority of air pollutant emissions in the ACT. In the absence of current data, it is not possible to assess changes in air pollution emissions over the reporting period. For PM2.5, smoke from wood heaters, bushfires and planned burns accounted for around 50% of the total levels, with wood heaters the main source contributing up to 75% of total PM2.5 in cooler months.
The ACT’s annual monitoring and reporting activities for point source emissions complied with the National Environment Protection National Pollutant Inventory Measure over the reporting period.
CONDITION
Environmental condition is healthy across the ACT, OR pressure likely to have negligible impact on environmental condition/human health.
Environmental condition is neither positive or negative and may be variable across the ACT, OR pressure likely to have limited impact on environmental condition/human health.
Environmental condition is under significant stress, OR pressure likely to have significant impact on environmental condition/ human health.
Data is insufficient to make an assessment of status and trends.
TREND
DATA QUALITY
Adequate high-quality evidence and high level of consensus.
Limited evidence or limited consensus.
Evidence and consensus too low to make an assessment.
Assessments of status, trends and data quality are not appropriate for the indicator.
Air pollution sources
For information on this indicator see Background: Air quality.
Knowledge on the sources of air pollutants is important for the management of air pollution. The sources and volumes of emissions of air pollutants in the ACT is reported in the National Pollutant Inventory. Whilst point source emissions are reported annually, the data on the sources and emissions of diffuse source air pollution dates from a single 1999 study. Consequently, in the absence of current data it is not possible to assess changes in air pollution emissions for this reporting period. Despite the lack of data, it is accepted that diffuse sources of air pollutants, especially from transport and wood heaters, are the most significant contributors to air pollution in the ACT.
Whilst there is no comprehensive data on the diffuse sources of air pollutants, the ACT Health Directorate undertook a study to determine sources of PM2.5. The study assessed PM2.5 levels recorded by the Monash and Florey monitoring stations from January 2017 and to September in 2018 (Figure 11). Preliminary results show that there are five main sources of PM2.5 including:
- Biomass burning — typically wood smoke from wood heaters and smoke from bush fires or hazard reduction burns in and around the ACT. Wood heater smoke is estimated to account for up to 75% of PM2.5 in cooler months.
- Secondary sulphates — emissions from coal-fired power stations outside of the ACT and local industry. The contribution of secondary sulphates increases in summer because of the greater sunlight which generates photochemical reactions in the atmosphere. Secondary sulphates are estimated to account for up to 80% of PM2.5 in hot months.
- Motor vehicle emissions can account for nearly 20% of PM2.5 emissions and are higher in colder months due to fuel combustion being less efficient.
Figure 11: Monthly sources of PM2.5 air pollution at the Monash Station, January 2017 to September 2018.
Data sourced from: ACT Health Directorate.
Over the entire study period, biomass burning was estimated to account for around 50% of the total PM2.5 levels (Figure 12), with wood heaters the main source. Secondary sulphates were the next highest source of PM2.5 at 21%, motor vehicles accounted for 13%, windblown soil 10%, and windblown salt 6% of the ACT’s PM2.5 pollution. Source contributions are estimated to be similar at both Monash and Florey monitoring stations.
Figure 12: Estimated total sources of PM2.5 air pollution in the ACT, January 2017 to September 2018.
Data sourced from: ACT Health Directorate.
NEPM compliance
Point-source emissions are regulated by the ACT Government. Maximum concentration limits are placed on certain substances being emitted from industrial sources; these limits are regulated through the Environment Protection Act 1997. There are several industrial facilities in the ACT that must report to the EPA on their total point-source emissions each year. The annual monitoring and reporting of point source emissions is required under the NPI NEPM. During the reporting period (up to and including 2022–23), the ACT’s monitoring and reporting activities complied with the NPI NEPM.
Data gaps
With the exception of PM2.5, there has been no comprehensive diffuse air pollution assessment since 1999. Consequently, it is not possible to fully assess air pollutant sources in the ACT.
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