AIR QUALITY

Particulate concentrations, PM₁₀Particles may be solid matter or liquid droplets. PM₁₀ particles (10 micrometres in diameter and smaller) are small enough to penetrate deeply into the lungs. Particles can aggravate existing respiratory and cardiovascular disease.

The current NEPM (National Environment Protection Measure) one-day standard for PM₁₀ is 50 µg/m³ (micrograms per cubic metre), with a maximum allowable exceedence of five days a year.

Particles result from various kinds of combustion, including bushfires and volcanoes. They are also emitted from industrial processes, motor vehicles, domestic fuel burning and industrial and domestic incineration.

Overall, air quality in Australia is relatively good. Between 1997 and 2001, the levels of PM₁₀ in Brisbane, Sydney, Melbourne and Perth met the NEPM annual standard. However, there was a rise in 2002 and 2003, mainly due to severe forest fires and dust storms around the Sydney, Canberra and Melbourne areas.

While four of the five cities with data available exceeded the one-day NEPM standard of 50 µg/m³, the extent to which the standard was exceeded varied between cities. In 2005, Brisbane’s highest daily concentration was 52.6 µg/m³, which exceeded the standard by 5%. Canberra’s highest daily concentration was 98.8 µg/m³. This can be attributed at least in part, to emissions from domestic wood heaters.

Particulate concentrations, PM_2.5

The National Environment Protection Measure (NEPM) was varied in 2003 to introduce advisory reporting standards for particles at PM_2.5 (particulate matter with an equivalent aerodynamic diameter of up to 2.5 micrometres (µm)).

The NEPM standard for particles up to PM_2.5 is 25 µg/m³ (micrograms per cubic metre) for one day.

Particle pollution is a major air quality issue in Australia. Particles can aggravate existing respiratory and cardiovascular disease. 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.

Ozone (photochemical smog)

Ozone or photochemical smog is a problem in most large cities. It is caused by emissions from industry, motor vehicles, domestic wood combustion and other sources, accumulating under certain meteorological conditions.

Ozone is produced photochemically in air by reactions between hydrocarbons and nitrogen oxides. Some hours of strong sunlight are required to allow high levels of oxidant to form. High levels are most likely to occur when there is abundant sunshine combined with high temperatures and wind conditions that limit dispersion.

Ozone affects the linings of the throat and lungs, restricting air passages and making breathing difficult. It also increases the risk of respiratory infections and eye irritation. The current four-hour standard level of oxidant is 0.08 parts per million (ppm). The maximum allowable exceedance is one day a year.

Ozone has been monitored in most cities since the late 1970s. Ozone levels have declined significantly since the 1970s, although in recent years a clear trend is not apparent. There is significant year-to-year variability in peak ozone levels due to weather variability.

The levels of ozone in the atmosphere vary between cities. Sydney was the only city that recorded a 4-hour ozone exceedence in 2005, as shown in the graph below. This is partly due to the topography of the Sydney Basin.

Sulphur dioxide

Sulphur dioxide (SO₂) is a colourless, irritating and reactive gas with a strong odour. In Australia, emissions of sulphur dioxide are primarily from industrial operations that burn fuels such as coal, oil, petroleum and gas and from wood pulping and paper manufacturing. It is also emitted by vehicles. It irritates the eyes, nose and throat, and people with impaired lungs or hearts and asthmatics are particularly at risk of exacerbating existing health problems.

Ambient SO₂ concentrations are generally low. Levels of SO₂ vary between regions due to varied geographical distribution of major sources and different topographical and meteorological conditions. Sulphur dioxide levels in Australian cities are low compared to the USA and Europe because of the limited number of major SO₂ emitting industries and low sulphur fuels.

Sulphur dioxide pollution has been an issue in some mining areas, but is generally improving. Due to improvements in mineral extraction and processing activities at Kalgoorlie in Western Australia, SO₂ levels have been reduced dramatically over the last 12 years.

In recent years, one-hour SO₂ levels have been below the National Environment Protection Measure (NEPM) standard levels at Gladstone, the Lower Hunter and La Trobe Valley (power generation areas using coal), however, levels remained high at Port Pirie and Mount Isa.

Carbon monoxide concentrations

Carbon monoxide (CO) is an odourless and tasteless gas, and cannot be detected by humans. Volcanoes and bushfires are natural sources of CO. In Australia, the main sources of additional CO are motor vehicles and specific industrial activities.

CO is poisonous to humans because it reduces the amount of oxygen that can be carried by red blood cells, resulting in insufficient oxygen reaching organs of the body to allow proper functioning.

The NEPM standard for CO is 9 parts per million (ppm) averaged over an 8-hour period. Between 2000 and 2005, no exceedances of the NEPM were recorded in Sydney, Melbourne, Brisbane, Perth or Adelaide.

Changes in the volume of road traffic impact on the concentration of atmospheric pollutants, such as carbon monoxide (CO).

There have been positive changes in fuel standards and vehicle design, resulting in a reduction in the concentration of CO in major Australian cities. This is despite a continued increase in the number of vehicles and the number of vehicle kilometres travelled.

In 2005, there were an estimated 13.9 million vehicles registered in Australia. Cars accounted for approximately three-quarters of all vehicles. Australian’s drove an estimate 206 billion kilometres in 2005, an increase of 8.5% since 2001.

Vehicle type	2001	2002	2003	2004	2005
Passenger vehicles	143 925	144 676	151 743	147 728	155 068
Motor cycles	1 448	1 681	1 376	1 478	1 429
Light commercial	30 728	31 349	32 671	34 007	33 764
Rigid trucks	6 627	7 080	7 768	7 639	7 671
Articulated trucks	5 321	5 425	5 841	6 013	6 308
Non-freight carrying trucks	267	224	203	221	286
Buses	1 835	1 775	1 893	1 968	1 856
Total	190 152	192 209	201 497	199 055	206 383

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Source: ABS, Survey of Motor Vehicle Use (cat. no. 9208.0).

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