Pollution sources


Pollution sources are often characterised as anthropogenic (i.e. human-made), biogenic (i.e. natural and living) or geogenic (i.e. natural and nonliving). For air quality, most of the concern is about anthropogenic emissions, because natural sources are generally not able to be controlled. However, the distinction is not always clear-cut—for example, management of woodland, including the use of prescribed burns (anthropogenic), could reduce the frequency or intensity of smoke emissions from bushfires (natural).

The most important anthropogenic sources of air pollution are motor vehicles, industry, and some commercial and domestic activities, especially domestic wood heaters. Other contributors to poor air quality include soil dust from the landscape, spray from waves breaking in the ocean, emissions from plants, and smoke from bushfires and prescribed burns. The contribution from pollution sources varies between regions (spatially) and time (e.g. summer–winter and day–night), depending on which sources are emitting in that area and at that time. The pattern of concentrations in Box ATM8 reflects the location of the sources but, as discussed under Introduction, the relationship between emissions and ambient air quality is often not so straightforward.

Figure ATM30 shows the proportion of anthropogenic-source categories in the Sydney region that contribute to total emissions of pollutants from the 2008 inventory (which was published in 2012). Detailed emissions inventories are available for Melbourne and south-east Queensland, but these have not been updated since SoE 2011. The commercial sources include the range of manufacturing and food processing that is typically found in industrial zones within, or on the edge of, urban areas. The domestic–commercial sources are principally domestic, but include aerosol and solvent emissions from commercial operations. They are dominated by emissions from domestic wood heaters and lawn mowing.

VOCs come from a wide range of sources:

  • those that emit solvents, including as aerosols, such as from spray painters and dry-cleaners
  • industrial sources, including major industries such as power stations, mining and chemical manufacturing
  • off-road mobile sources, including locomotives, shipping and boating, off-road vehicles and equipment, and aircraft
  • on-road mobile sources, including both tailpipe and non-tailpipe sources (e.g. brake dust) from vehicles registered for on-road use.

Notable changes in the inventory since SoE 2011, when the 2003 inventory was available, include less total sulfur dioxide from industry, and a greater fraction of sulfur dioxide emitted from off-road mobile sources such as shipping. The proportion of on-road mobile sources of carbon monoxide has decreased in the 2008 inventory, and domestic commercial activities have increased. The proportion of lead emissions from industrial processes has increased in the 2008 inventory.

Box ATM8 Future air quality in Victoria project

Work from CSIRO and the Victorian Environment Protection Authority forecasted what air quality in Victoria might be like in the year 2030 (EPA Vic 2013). The project investigated changes between the base year–2006–and 2030, including predicting how the Victorian emissions might change because of population increases, and what impacts climate change might have on day-to-day air quality through changes in weather conditions.

New technology is likely to reduce emissions from motor vehicles, even though the use of transport will increase because of an increasing population. The projected Melbourne–Geelong population increase of 45 per cent will place a higher demand on power generation, and increase the emissions from domestic and small business sectors. The projected increase in population will mean that more people are exposed to air pollution, especially the increased proportion of people aged 65 years and over. Increased occurrences of air pollution–related health effects, such as heart and lung disease, are expected.

Modelled concentrations of pollutants were compared with current air quality standards. Concentrations of nitrogen dioxide; sulfur dioxide; carbon monoxide; and air toxics such as formaldehyde, benzene, toluene and xylene are expected to decrease in the Melbourne–Geelong area by 2030. Levels of particulate matter less than 2.5 microns will continue to be concentrated in the central business district and inner suburbs, which have the highest vehicle and population density (Figure ATM31). Secondary pollutants such as ozone also remain a concern in 2030.

Climate change had only a small impact on 2030 urban air quality in the model, but the impact is expected to be greater beyond 2030. The frequency of droughts and temperature-driven smog events is expected to increase beyond 2030 if emissions are not reduced. Increased droughts will increase dust events and, combined with the increase in temperature, increase bushfire events.

The results from this study are being used to inform future air quality management in Victoria, and to support the National Clean Air Agreement.

Source: EPA Vic (2013)

Keywood MD, Emmerson KM, Hibberd MF (2016). Ambient air quality: Pollution sources. In: Australia state of the environment 2016, Australian Government Department of the Environment and Energy, Canberra, https://soe.environment.gov.au/theme/ambient-air-quality/topic/2016/pollution-sources, DOI 10.4226/94/58b65c70bc372