State of the Environment Report 2007
Air toxics are classed as an emerging issue due to its potential to cause significant impacts to human health, however there is currently inadequate information to report more fully on this issue.
Air toxics are gaseous, aerosol or particulate pollutants that are present in the air in low concentrations and have toxicity or persistence that is hazardous to human, plant or animal life (National Environment Protection Council, 2005). The term 'air toxics' includes a very wide variety of chemicals and compounds. While air toxics can be released from natural sources such as bushfires, the major emission sources are related to industry, motor vehicles, cigarette smoking and building products and equipment. The highest concentrations of toxic emissions originate from industrial processes and the combustion of fossil fuels for these processes. However, motor vehicles contribute the highest overall load of air toxics to the atmosphere (Tibbett, 2004).
Many air toxics are highly volatile and evaporate readily into air, allowing inhalation. While the levels that endanger public health have not been established, it is believed that long-term exposure to even very low levels could have adverse effects. Some health effects may take many years to become evident and some air toxics have synergistic effects (causing higher toxic effects in combination than individually). Cancer, pulmonary disease, neurological or gastrointestinal effects, respiratory congestion and irritation to the eyes, nose and throat are some of the serious or debilitating effects of exposure to air toxics (Tibbett, 2004). Native fauna and flora are also susceptible to toxic effects.
In Australia, some air toxics have been recognised in the National Environment Protection (Air Toxics) Measure which designates levels of pollutants at which investigation should occur (as opposed to standards set for ambient air quality) (National Environment Protection Council, 2004a). The pollutants covered by the air toxics NEPM are benzene, benzo(a)pyrene (as a marker for polycyclic aromatic hydrocarbons), formaldehyde, toluene and xylenes. Through the Living Cities Air Toxics Program, the Commonwealth Government identified a group of priority pollutants as a starting point for focusing attention on the development of national strategies for the management of air toxics (Table A8.1).
The key air toxics of concern in WA include heavy metals, benzo(a)pyrene (polycyclic aromatic hydrocarbons), volatile organic compounds, persistent organic pollutants and asbestos. Very limited data on the levels of these pollutants is available and in some cases no data is available. Heavy metal air toxics include arsenic, lead (indoor air), cadmium, mercury, chromium, nickel and their associated compounds. While lead levels in Perth were historically high, it is no longer considered to be a problem (see 'Outgoing issue - Lead'). The Perth Haze Study found polycyclic aromatic hydrocarbon levels in Perth were high in Duncraig (an area impacted by wood smoke) compared to Swanbourne and Caversham (Department of Environmental Protection, 1996; Environment Australia, 1999). Volatile organic compounds include benzene, toluene, chlorofluorocarbons (CFCs), halons, carbon tetrachloride and some pesticides. Studies of airborne reactive organic compounds in Perth have shown low levels of volatile organic compounds, benzene, toluene, ethylbenzene and xylene (Department of Environmental Protection, 2000b; Environment Australia, 2003) compared to other Australian cities and the relevant standards. The Background Air Quality (Air toxics) Study gathers data for some air toxics at thirteen metropolitan sites and compares them to NEPM guidelines and international standards. Results have been recorded for volatile organic compounds at sites in Albany and Kalgoorlie (see former Department of Environment website), but data have not yet been analysed in detail.
