ACT State of the Environment 2007

Indicator: Air emissions


In 2005–06, 62 toxic substances listed on the National Pollutant Inventory were known to be emitted to air, land or water in the ACT. They came from 49 known sources or categories. The single largest source was motor vehicles.

What the results tell us about the ACT

The National Pollutant Inventory (NPI) is a list the Australian Government Department of the Environment, Water, Heritage and the Arts maintains. The NPI provides the community, industry and government with free information about substance emissions in Australia. The NPI shows emission estimates for 93 toxic substances along with the source and location of those emissions. The NPI is a cooperative program implemented by the Australian, state and territory governments.

Of the 93 substances on the NPI, 62 are emitted in the ACT. Not all listed substances are necessarily significant to the state of the environment, but they are considered harmful to human health (in high enough doses); it is therefore useful to maintain a database of them. It should be clearly stated that just because a toxic substance is emitted does not necessarily imply danger to public health. The concentration of the pollutant in air is a key factor, along with its dispersal rate and its longevity. Many compounds break down quite rapidly into non-toxic forms. Naturally, proximity to the source of the emission is more dangerous than being upwind of it. For example, breathing in air straight from a car's exhaust pipe is known to be dangerous, whereas if a car drives past your house it probably does not pose a risk to your health because the concentration of the emitted substances would be too low.

The ACT has no heavy industry or power stations burning coal or oil, so the primary source of atmospheric emissions in the Territory is from motor vehicles. The other significant source is burning solid fuels, especially wood for heating. Bushfires, when they occur, can also be a major source. Other sources of emissions are from leaking gas appliances, landfill, waste disposal, agricultural activities, petrol stations and paints and other substances used on the outside of buildings.

Many of the NPI pollutants are classified as 'air toxics' or 'hazardous air pollutants'. These can be gases, aerosols or particulates present in the air in low concentrations that are sufficiently toxic to be a hazard to human, plant or animal life. Air toxics include volatile and semi-volatile organic compounds (toluene, xylene, carbon tetrachloride), polycyclic aromatic hydrocarbons (benzene and derivatives), heavy metals (cadmium, mercury) and aldehydes (formaldehyde). It is unclear what, if any, health impacts they may have when present at extremely low concentrations. There are insufficient data about many of the compounds and their possible effects, particularly because in people the effects may not become evident for decades or may not necessarily be directly attributable to exposure.

Motor vehicles

National legislation governs the quantities of carbon monoxide, hydrocarbons and oxides of nitrogen that cars can emit in their exhaust stream.1 The first such pollution control legislation, Australian Design Rule (ADR) 37/00, came into force in 1986. Cars made in Australia from 1997 onwards must comply with stricter controls, as set out in ADR 37/01. Even stricter controls came into force for cars manufactured from 2003 (ADR 79/00, also known as Euro 2). In 2005–06, ADR 79/01(Euro 3), came into force, further restricting allowable emission volumes.

The NPI estimates that motor vehicles are the largest single source of atmospheric emissions in the ACT, accounting for about 26.4% of all emissions to air in 2005–06. This is a slight increase on the previous reporting period (24%), which is to be expected as the Territory's vehicle fleet is growing (in 2005 it was 217,000 vehicles, compared to 212,000 in 2003). The average distance travelled has, however, decreased slightly. Total vehicle emissions within the Territory are not likely to be greatly affected by small changes in the average distance travelled per year, but are likely to be affected by the increase in the number of vehicles on the roads.

According to the New South Wales Environmental Protection Agency, motor vehicles in New South Wales account for 70% of oxides of nitrogen emissions, 52% of emissions of volatile organic compounds and 23% of particulate emissions in urban areas. It is likely that these percentages are similar for these pollutants in the Canberra urban area. Motor vehicle emissions are affected by various factors, including the type of vehicle and its age, the fuel used, how well maintained the vehicle is, and how and where it is driven.

The average age of private motor vehicles in the ACT is about 10 years and most would have been built to comply with the 1986 legislation; much of it would now comply with the 1997 ADR and more recent ones.

Despite the laudable introduction of stricter design rules, there is no escaping the fact that motor vehicles are severely polluting and will remain so while they use internal combustion engines running on hydrocarbons.

Non-vehicle emissions

The second most important source of emissions of NPI substances, especially particulates, in the ACT is solid fuel burning, accounting for 12.5% of emissions (see Outdoor Air Quality indicator).

Industrial facilities are required to report emissions if they use more than a set level of one or more substances on the NPI, or consume more than a specified amount of fuel or electric power. Although the Territory has few industrial facilities, 23 are required to report to the NPI. Most emit very small amounts of listed pollutants.

Smoke from solid fuel heating contains a range of pollutants. These include those covered by the National Environment Protection (Ambient Air Quality) Measure (for example, particulate matter, carbon monoxide and nitrogen dioxide), as well as a broad range of air toxics. Air toxics found in wood smoke include benzene, toluene and xylenes, formaldehyde and polycyclic aromatic hydrocarbons (Environment Australia 2002).

The ACT has a winter particle pollution problem due to emission from wood heaters used for home heating. The wood smoke problem is exacerbated by stable weather conditions that lead to poor dispersion of air pollutants. It is common to see a layer of wood smoke enveloping the city during winter, particularly in the Tuggeranong Valley. The ACT Government has developed a Wood Heater Replacement Program that aims to reduce winter air pollution from wood smoke by offering a subsidy to eligible householders for replacing a wood heater with a gas heater. Since the beginning of the program in 2004, 600 wood heater rebates have been delivered.

Australian Standards have been developed to cover emissions for new wood heaters. The ACT Government requires that wood heaters, including wood heaters installed in new homes, comply with these standards.

Some jurisdictions run public awareness campaigns to increase understanding of the community health problems associated with wood heaters. These are generally supported by community education campaigns aimed at reducing wood heater emissions through better operation. The ACT Government ran campaigns in shopping centres during this reporting period but are now focusing on encouraging residents to make the switch to gas heaters by taking up the rebate.

A national program, based on a voluntary code of practice, is in place to improve the quality of firewood supplied by retail firewood merchants. This has the potential to reduce emissions caused by burning unseasoned or contaminated firewood.

While these programs are primarily aimed at managing winter haze and smoke issues associated with domestic wood heaters, they clearly have an impact on the air toxics considered under the proposed National Environment Protection Measure.

Aviation emissions

Aviation emissions are directly related to the number of aircraft movements. Movements at Canberra International Airport have remained relatively stable over the past few years (Australian Bureau of Statistics 2007:179). Airservices Australia is currently trialling a system that among other benefits will reduce emissions from aircraft (Airservices Australia 2008).

Data sources and references

Airservices Australia, 2008, RNP – Brisbane Green Project – Stage 1 Report at <> last viewed 28 March 2008

Australian Bureau of Statistics (Australian Bureau of Statistics), 2007, ACT In Focus, Catalogue No. 1307.8

Department of Infrastructure, Transport, Regional Development and Local Government, Australian Design Rules website at <> last viewed 28 March 2008

Department of the Environment Water, Heritage and the Arts, National Pollutant Inventory website at <> last viewed 28 March 2008

Environment Australia, 2002, Review of literature on residential firewood use, wood-smoke and air toxics, Technical Report No. 4
<> Last viewed 26 March 2008

Environment Protection and Heritage Council, Ambient Air Quality website at <> last viewed 28 March 2008


1 Motor vehicles emit cyclohexane, cobalt and compounds, copper and compounds, n-hexane, manganese and compounds, polycyclic aromatic hydrocarbons, zinc and compounds, acetaldehyde, acetone, benzene, 1,3- butadiene, cadmium and compounds, carbon monoxide, chromium (III) compounds, chromium (VI) compounds, ethylbenzene, formaldehyde, nickel and compounds, oxides of nitrogen, particulate matter, styrene, sulphur dioxide, toluene and xylenes. Many of these compounds are classified as volatile organic compounds and would be controlled by the ADR ruling on hydrocarbons. However, the ADRs do not restrict several other substances, such as cobalt, copper, nickel and sulphur dioxide. Some of these come from operation of the brakes and the wheels, rather than from the engine.

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