Air pollution has many sources, including industry, motor vehicles, the home (e.g. from solid fuel heaters), and sporadic natural events, such as bushfires. The impact of air pollution can be viewed from a global, regional or local perspective.
Recently, international concern has turned to a number of air pollutants which, though found in relatively small concentrations, have the potential to adversely affect human health and the environment through long-term exposure. These substances have been given a variety of names including `hazardous air pollutants' and `air toxics', the term adopted in this report.
Scientific understanding of the identity and risk posed by these pollutants is evolving. As a result of this still limited knowledge, the elements and compounds viewed with the greatest concern varies between countries and states.
To assess the local situation, the NSW Government provided $1.4 million for the Environment Protection Authority (EPA) to study the presence of air toxics at sites representative of general urban air quality in the Sydney-Newcastle-Wollongong area. Sampling for a specific type of air toxic â€“ polycyclic aromatic hydrocarbons (PAHs) â€“ also occurred at a number of larger regional centres: Armidale, Cooma, Lithgow, Nowra, Orange and Tumut. Throughout the study, sampling was more intensive at those times of year when pollutant concentrations were expected to be highest.
The primary aim of the program was to obtain data on the concentrations of a wide range of air toxics. Altogether, the study ran for 5Â½ years from early 1996 to August 2001. It examined dioxins, 41 organic compounds, 11 PAHs and 12 heavy metals. In total, the concentrations of over 80 substances were measured, with more than 1400 samples collected at a total of 25 sites.
Armed with this large amount of data and in the absence of any Australian standards, the EPA compared the results with the overseas standards available. Where none existed the EPA measured results against either proposed or future standards or reported levels from other jurisdictions.
In summary, the study found that most air toxics levels in NSW are low and well below current international standards and benchmarks. However three of the pollutants â€“ benzene, 1,3-butadiene and PAHs at some sites â€“ will need ongoing vigilance to ensure their currently acceptable levels do not escalate in the future.
Ambient dioxin concentrations measured in Sydney, Wollongong and central-western NSW were very low when compared with current standards in both Europe and the US, and measured concentrations in other countries.
The NSW management program for dioxins has involved strict control and reduction by:
- banning backyard burning
- closure of some sources, especially hospital incinerators
- licensing and regulation of industrial sources
- reducing emissions from solid fuel heaters
- a phase-out of leaded petrol for cars.
The low concentrations of dioxins found in this study indicate that these control strategies have been effective, and are likely to continue to be so.
The annual average concentrations of organic air toxics measured in this study in the Sydney-Newcastle-Wollongong area were also very low. Many of the commonly recognised air toxics were not detected in any samples. Twenty-two of the 41 organic compounds sampled were either not detected in any of the samples (12 compounds) or rarely encountered (10 compounds detected in fewer than 1% of the 1000 samples). The measured levels of organic air toxics were below all current international goals or standards. However, benzene and 1,3-butadiene were present at concentrations which approached, but did not exceed, the goals for these substances.
The major sources of benzene and 1,3-butadiene are motor vehicles and their fuel. Several recently introduced programs aim to reduce emissions from motor vehicles, including:
- stricter national emission standards for new vehicles
- introduction of national fuel quality standards, including a maximum limit on benzene in petrol of 1% from 2006
- lower volatility petrol in summer in the Sydney region
- the Cleaner Vehicles Plan promoting vehicles which run more cleanly in NSW
- voluntary emissions testing for cars
- programs to encourage alternative forms of transport to reduce vehicle use.
These programs and initiatives will all reduce benzene emissions. However, the Government will continue to evaluate the effectiveness of these strategies and strengthen them as necessary to avoid increasing levels of benzene and 1,3-butadiene.
Substances that damage the stratospheric ozone layer (such as FreonsÂ®) and those substances banned or being phased out under the Montreal Protocol showed little difference from global background levels. This suggests that existing strategies, which prohibit the use and release of ozone-depleting substances through regulation, are having the intended effect.
In winter some parts of Sydney and a number of larger centres in the Great Dividing Range suffer from visibly high levels of smoke associated with solid fuel heating and still weather. The study set out to determine the types and indicative concentrations of polycyclic aromatic hydrocarbons (PAHs) in ambient air associated with the expected winter seasonal peaks in these problem areas.
Concentrations of PAHs at urban sites in outer Sydney, Newcastle, Wollongong and Nowra are easily lower than proposed international goals for these substances. Concentrations in the Sydney CBD and at Earlwood were in the vicinity of the goals and levels in some regional centres-Armidale, Cooma, Lithgow, Orange and Tumut-were elevated in winter. The pattern of emissions in these regional centres corresponds to the high usage of solid fuel heaters burning wood. The local practice in Lithgow of burning coal as well as wood is believed to contribute to the even higher levels of PAHs there. Existing strategies to reduce PAH emissions from solid fuel heaters are therefore confirmed as priorities by the study.
One program, for example, the NSW Government's targeted wood and coal smoke reduction program, is already in place to reduce PAH emissions from solid fuel heaters. The program involves an allocation of $1 million to selected local councils to step up education and enforcement programs and subsidise the cost of switching to non-solid fuel heating sources in the most affected areas: Armidale, the Blue Mountains, Cooma, Lithgow, Orange and Tumut. The effectiveness of this program will be monitored to decide if it should be extended to other areas.
A survey of heavy metals at urban sites found that the concentrations of the 12 metals measured were low when compared with levels at comparable sites overseas. They were all below applicable standards or goals, where these exist. Concentrations near some industrial sites will continue to be monitored as part of the licensing of those facilities. The sources of these emissions will be further reviewed to identify possible sites where focused local reduction programs might be effective.
Page last updated: 26 February 2011