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1.1 Background

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 considered from a global, regional or local perspective.

Historically, industrial point sources of pollution have been the focus for regulation by agencies such as the Environment Protection Authority (EPA). More recently, however, the cumulative impact of millions of small sources such as motor vehicles has been recognised as a dominant contributor to regional and global air quality.

To date, regional air management has concentrated on controlling six priority pollutants identified as having the potential to adversely affect human health and the environment at the levels sometimes found in urban areas. These six, included in the National Environment Protection Measure (NEPM) on Ambient Air Quality and known as `criteria pollutants', are:

• ground-level ozone (photochemical smog)
• nitrogen dioxide
• particles (up to 10 micrometres in diameter)
• sulfur dioxide
• lead
• carbon monoxide.

The NEPM sets national goals for regional concentrations of these pollutants. NSW monitoring data on them is included in the annual report of the National Environment Protection Council and daily readings for these pollutants are also reported on the EPA's website.

More recently, international concern has turned to a number of other air pollutants which, though found in relatively small concentrations, may also have a detrimental effect on human health and the environment through exposure over many years. This latter group of substances has been given a variety of names. The United States Environmental Protection Agency (US EPA) calls them `hazardous air pollutants'. Elsewhere they are known as `air toxics' and this is the term adopted here. Air toxics do not include the criteria pollutants referred to above.

Air toxics cover a broad range of pollutants, and scientific understanding of their identity and the risk they pose is only evolving. Because of this limited knowledge, the elements and compounds viewed with greatest concern varies between countries and states.

As a result of this growing international focus on the hazards of air toxics, the NSW Government provided $1.4 million for the EPA to study a comprehensive range of these pollutants in urban areas and some regional centres across the State. Altogether, the study ran for 5½ years from early 1996 till August 2001.

An earlier pilot study in Sydney in 1995 and 1996 tested for the presence of 40 air toxic organic compounds covered by the US EPA standard test method (TO-14). The pilot successfully trialled the methodology and recommended that measuring continue to develop a more representative data set on air toxics.

The pilot also recommended extending the studies to include 1,3-butadiene, polycyclic aromatic hydrocarbons (PAHs) and a range of heavy metals as a companion to the TO-14 studies. These have been included in the new EPA study, together with dioxins, to give a more complete picture across the spectrum of air toxics.

The EPA conducted the latest study to find out whether, at a regional level, the more significant air toxics are present in NSW and, if so, at what concentrations. A comparison of concentrations here with current goals and levels overseas should indicate if further action is needed to control or reduce air toxics.