Air quality fact sheet
Department of the Environment and Heritage, 2005
Airborne particles are sometimes referred to as 'particulate matter' or 'PM'. They include dust, dirt, soot, smoke, and liquid droplets. Some particles are large enough or dark enough to be seen as soot or smoke, while others are so small they can only be detected individually with a microscope.
Some particles are emitted directly into the air from a variety of sources that are either natural or related to human activity. Natural sources include bushfires, dust storms, pollens and sea spray. Those related to human activity include motor vehicle emissions, industrial processes (eg electricity generation, incinerators and stone crushing), unpaved roads and woodheaters.
Particles can be classified on the basis of their size, referred to as their 'aerodynamic diameter'. 'Coarse particles' are those between 10 and 2.5 micrometres (µm) in diameter; 'fine particles' are smaller than 2.5 µm; and 'ultrafine particles' are smaller than 0.1 µm. For comparison, the diameter of a human hair is 70 µm and this is seven times the diameter of the largest 'coarse particles'.
Particles can also be classified according to their chemical composition. The toxicity of particles is often dependent on their size and chemical composition.
Studies have linked exposure to particle pollution to a number of health problems including respiratory illnesses (such as asthma and bronchitis) and cardiovascular disease. In addition, the chemical components of some particles, particularly combustion products, have been shown to cause cancer. These effects are often more pronounced for vulnerable groups, such as the very young and the elderly.
Particle pollution is the major cause of reduced visibility. This can be a serious safety issue on roads and in traffic tunnels and can also affect our enjoyment of the natural landscape.
Particle pollution is a major air quality issue in Australia. In some regions of Australia, particularly during the cooler months, woodsmoke from woodheaters results in elevated particle levels that are a health risk for many in the community. Meteorological conditions, such as still air and inversions (where cold air is trapped below warm air), can slow down the removal of pollutants and increase the impacts of this pollution.
The Australian Government has taken steps to manage the amount of particles produced and to increase our understanding of the nature and impacts of particles. These steps include:
- implementing national fuel quality standards and promoting alternative fuels;
- supporting the implementation of tighter vehicle emission standards;
- developing a National Environment Protection Measure for Diesel, to improve the in-service performance of diesel vehicles;
- working with State and Territory governments and the woodheater industry to improve woodheater technology, woodheater operation, and compliance with the Australian Standard for woodheater particle emissions, AS 4013;
- working with State and Territory governments so that the same sized fine particles are measured in the same way at all points in a new national monitoring network;
- researching the formation of secondary particles by photochemical reaction;
- developing pollution forecasting systems for Australia's major cities;
- promoting bicycle use for short journeys through CycleConnect; and
- working with the States and Territories through programs such as TravelSmart to influence passengers transport choices.
The Australian, State and Territory Governments have also agreed on a National Environment Protection Measure for Ambient1 Air Quality. (See factsheet on National Standards for Criteria Air Pollutants) The Measure sets an air quality standard for PM10 of 50 micrograms per cubic metre (50 µg/m³) in outdoor air averaged over a 24-hour period. The goal, to be met by 2008, is for the standard to be exceeded no more than five days a calendar year.
The Measure was varied in 2003 to include advisory reporting standards for PM2.5. These are: 25 µg/m³ averaged over 24 hours; and 8 µg/m³ averaged over one year. The goal of the variation is to collect sufficient PM2.5 monitoring data to allow the development of air quality standards.
Related publications are available from the Community Information Unit of the Department of the Environment and Heritage, phone 1800 803 772. These include the State of the Air Report: Community Summary 1991–2001 and Air Quality fact sheets on:
- National Standards for Criteria Air Pollutants in Australia;
- carbon monoxide, lead, nitrogen dioxide, ozone, sulfur dioxide, air toxics;
- woodheaters and woodsmoke; and
- smoke from biomass burning
See also our website at Air quality
1 In this context, 'ambient' means 'outdoor'.