Overall, air quality in Australia is relatively good and has generally improved during the 1990s. (SEE FOOTNOTE 1) Our cities do not suffer from the acute pollution problems found in many OECD countries. (SEE FOOTNOTE 2)

Poor air quality has a range of negative impacts: it can cause health problems, damage infrastructure, reduce crop yields and harm flora and fauna. For about a decade, the Australian public has been more concerned about air pollution than about any other environmental problem. (SEE FOOTNOTE 3)

Ideally, a headline indicator would encapsulate all aspects of air quality. But pollution takes many forms and there is, as yet, no agreed way in which different pollutants could be combined into just one measure. The headline indicator considers the concentration of fine particles in the atmosphere, a measure of the form of air pollution about which many health experts in Australia are most concerned. (SEE FOOTNOTE 4)

Most pollutants are more common in urban and industrial areas than in rural Australia. As there is little long-term information about air quality over much of Australia, the graph summarises data from Sydney, Melbourne, Adelaide, Perth and Brisbane.

The average number of days each year when health standards were exceeded in the selected urban areas showed a declining trend between 1994 and 1999. In 1994, 16 days in Brisbane, 12 days in Sydney, seven days in Adelaide, six in Perth and two in Melbourne exceeded health standards (a weighted average of over eight days). In 1999 the average number of days when standards were exceeded was less than 1.5, with four areas exceeding standards only once, and Adelaide exceeding them on six days.

Moreover, data for Sydney, Brisbane and Adelaide are available for a longer time period. These data also show that fine particle pollution between 1996 and 1999 was consistently below the levels in the years 1990 to 1995. (SEE FOOTNOTE 2)

Other pollutants also have negative impacts. In urban areas concentrations of lead levels dropped significantly during the 1990s and, together with sulfur dioxide and nitrogen dioxide, they are not a concern in any urban areas. (SEE FOOTNOTE 1) Carbon monoxide is only of concern in a few specific urban localities, but there has been no real drop in the incidence of photochemical smog. (SEE FOOTNOTE 1)

FINE PARTICLES Fine particles (PM10) are particles of any substance less than 10 micrometres in diameter, and include sulfates, nitrates, carbon and silica. They are generated by fossil fuel combustion, domestic wood fires and some industries, and also arise naturally from wind-blown dust, pollens and bushfires. The finest particles, those less than 2.5 micrometres in diameter (PM2.5), are the main cause of urban haze, which typically appears white. There is increasing evidence that these finer particles are of considerably more concern than those between PM10 and PM2.5 in size, and that most of these finer particles are generated by people, rather than occurring naturally. (SEE FOOTNOTE 5) The human health effects are many and depend on the size and chemical composition of the particles. Fine particles can penetrate deep into the lungs where they may be absorbed into the blood. The smallest particles can affect vision. Some particles are carcinogenic, while others are toxic or cause allergies. General effects include respiratory problems which can lead to sickness or even death among sensitive people. Some plants and animals are particularly sensitive to fine particle pollution. Lichens for example are often among the first life forms to be affected, while particles can cover the leaves of larger plants and damage their ability to photosynthesise.

SOME DIFFERENCES WITHIN AUSTRALIA

Different parts of the country experience different types and levels of air pollution, but air quality outside the major cities seems generally good, and levels of pollutants are generally well below actual or proposed standards. (SEE FOOTNOTE 1) Fine particles (particularly wind blown dust) are often the principal air pollution problem in most of our regional centres. (SEE FOOTNOTE 1) Some areas, far from major sources of pollution, can suffer from the long range transport of pollutants. Bushfires and controlled burn-offs also pollute. (SEE FOOTNOTE 1) There appears to have been overall progress in the 1990s. Sulfur dioxide emissions dropped by 30% between 1996 and 2001, while dust loads in mining areas have been reduced. (SEE FOOTNOTE 1) However, there remain some localised problems in areas such as Port Pirie and Mount Isa. (SEE FOOTNOTE 1)
Climate is also an important determinant of the amount of pollution experienced in Australia's cities and when the pollution occurs. Weather patterns that result in low or no wind are more likely to produce air pollution. Pollution conducive days usually occur in the summer and spring in all of our coastal capital cities. Brisbane can also expect them in the winter. (SEE FOOTNOTE 3)


FACTORS INFLUENCING CHANGE

Our air has always contained natural substances like sea-salt or gases from decaying plants and animals. But industrial activity and the growth in fossil-fuel dependent traffic have released millions more tonnes of pollutants into the air (over a million tonnes in 1998-99 alone) (SEE FOOTNOTE 6). Most of these emissions are from the use of fossil fuels.

Motor vehicles are Australia's single largest source of air pollution. (SEE FOOTNOTE 1) In Sydney, for example, in 1999- 2000 more than 25% of all PM₁₀ emissions were generated by motor vehicles. (SEE FOOTNOTE 6) Cars and trucks generate particles directly through burning fossil fuels, especially diesel, which not only generates far more particles than petrol per litre, but generates more of the finest particles (those less than 2.5 micrometres) which, evidence increasingly suggests, have the most serious health implications for humans. (SEE FOOTNOTE 7) Vehicles also generate particles when tyres lose rubber, and tyre and air turbulence wear away road surfaces.

Motor vehicles also emit other types of air pollution. In the mid-1990s, traffic accounted for more than 75% of emissions of carbon monoxide (which can affect memory and vision, cause heart disease and harm unborn children), and most of the oxides of nitrogen (which can form smog), and was a major contributor to many volatile organic compounds (which contribute to smog). (SEE FOOTNOTE 1) Industries that contribute to fine particle pollution include those that burn fossil fuels to make heat and power (such as power plants, and iron and steel works), refineries, mines and quarries, cement works, mineral processing plants and some agricultural activity (controlled burning and eroded soil generate fine particles). (SEE FOOTNOTE 6) Domestic wood heating can also have a significant effect. (SEE FOOTNOTE 5)

But although industrial activity and the numbers of cars grew during the 1990s, measured air quality has not deteriorated significantly. Technology and strategies designed to control air pollution appear to have countered the rises which would have been expected given the increases in pollution sources. (SEE FOOTNOTE 3)

For instance, diesel vehicles contribute almost three-quarters of all vehicular fine particle emissions. However, projections prepared for the National Road Transport Commission suggest that by 2015, despite significant growth in numbers of diesel vehicles (light commercial vehicles in particular), fine particle emissions from all diesel vehicles will fall in the major cities to about 70% or less of their 1996 levels. (SEE FOOTNOTE 8) The main reason for the predicted fall is that older vehicles will be replaced by newer, less polluting vehicles.

Cars and trucks are becoming cleaner in other ways too. For example, the switch to unleaded petrol and the use of catalytic converters has led to significant reductions in lead pollution in some areas (lead concentration at Mascot, inner Sydney, fell by some 60% between 1993 and 1996). (SEE FOOTNOTE 9)

A greater use of renewable power sources to generate energy could also reduce some forms of air pollution.


LINKS TO OTHER DIMENSIONS OF PROGRESS

Air quality is linked to health. While the full effects of pollutants like fine particles are still poorly understood, Australian studies are consistent with those overseas which show that days of high pollution levels show increased mortality rates, hospital admissions and emergency room visits for respiratory and cardiovascular disease. (SEE FOOTNOTE 3)

Polluted air can harm biodiversity: smog and acid rain can affect many plants and animals. (SEE FOOTNOTE 10)

Air quality is linked to the generation of income. Economic activity, especially among the more energy-intensive industries, creates pollution. But in turn, air pollution has financial impacts, such as the cost of cleaning buildings, while acidic gases in the atmosphere can corrode iron and steel. Agriculture can also be affected: polluted air can harm crops and livestock.

Land clearance and degradation contribute to air pollution: fine particles are created when vegetation is burnt, and when eroded soil is blown into the air.

See also the commentaries Health, National income, Biodiversity, Land clearance, and Land degradation.


FOOTNOTES

1 State of the Environment Advisory Council (SEC) 2002, Australia - State of the Environment Report 2001, SEC, CSIRO Publishing, Melbourne.

2 Organisation for Economic Co-operation and Development (OECD) 2000, Environmental Performance Reviews, OECD, Paris.

3 Australian Bureau of Statistics 2001, Australia's Environment: Issue and Trends, Cat. no. 4613.0, ABS, Canberra.

4 Experts, such as those who wrote Urban Air Pollution in Australia (at 7 below) generally mention both smog and fine particles as the two forms of air pollution with the most serious impacts on health. But evidence is mounting that fine particles, in particular those less than 2.5 micrometres in diameter, are the most serious of all.

5 National Environment Protection Council (NEPC) 1998, Ambient Air Quality: Final Impact Statement for the Ambient Air Quality NEPM, NEPC, Adelaide.

6 The National Pollutant Inventory (NPI) was set up in 1996 to quantify, for the first time, the amount of pollution released into the environment at a national level. The NPI.s database provides a comprehensive record of pollutants entering the air, land and water. Its first reporting period was 1998-99, and so it is still too early to consider national trends in air pollution, although this should be possible in a few years. Environment Australia 2002, National Pollutant Inventory: Particulate Matter 10.0 micrometres. URL: http://www.npi.gov.au last viewed 7 March 2002.

7 Australian Academy of Technological Sciences and Engineering (AATSE) 1997, Urban Air Pollution in Australia, AATSE, Melbourne.

8 Cox, J. 2001, Diesel Fleet Characteristics: Emissions Projections Update, National Environment Protection Council, Adelaide.

9 Cohen, D. 1996, "Have fine particle lead concentrations fallen in Sydney during the last 4 years?", in (ed.) Smith, A. Proceedings of the 13th International Clean Air and Environment Conference, Clean Air Society of Australia and New Zealand, pp. 238-243.

10 Commonwealth Scientific and Industrial Research Organisation (CSIRO) 2000, Urban and Regional Air Pollution: Information sheet, URL: www.dar.csiro.au/info/material/airpoll.htm last viewed 8 March 2002.

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