Potentially, air pollutants can be found in air anywhere - outdoors and indoors. Air pollutants can be divided into three groups:
Criteria pollutants
'Criteria air pollutants' is a term used internationally to describe air pollutants that have been regulated and are used as indicators of air quality. The regulations or standards are based on criteria that relate to health and/or environmental effects. One key feature of criteria air pollutants is that they are generally widely distributed across the country.
Australia has set national standards for six criteria air pollutants in outdoor (or ambient) air: carbon monoxide, lead, nitrogen dioxide, ozone, particles and sulfur dioxide. A Factsheet is available for each of these air pollutants:
Air quality in Australia
Information about air quality in major urban airsheds in Australia is available in the State of the air: national ambient air quality status and trends report 1991-2001. The report presents an analysis of national air quality based on 2001 data for the criteria pollutants, and examines the trends over the past decade or so, with emphasis on the period from 1991 to 2001.
This report indicates that particles and ozone are the air pollutants of concern in Australia, having peak concentrations at or above national air quality standards and showing no consistent downward trend in some major cities. For this reason, the Australian Government is supporting the States and Territories in their efforts to reduce levels of particles and ozone in Australia's urban airsheds.
Air toxics
Air toxics are sometimes referred to as 'hazardous air pollutants'. The Living Cities-Air Toxics Program defines air toxics as 'gaseous, aerosol or particulate pollutants that are present in the air in low concentrations with characteristics such as toxicity or persistence so as to be a hazard to human, plant or animal life'. See factsheet on Air Toxics.
Sources of air toxics include motor vehicle emissions, solid fuel combustion, industrial emissions, and materials such as paints and adhesives in new buildings.
Air toxics have the potential to cause serious harm to human health and/or the environment. For this reason, the Commonwealth, States and Territories have been working together to assess the risks posed by these pollutants. The Living Cities: Air Toxics Program, which concluded in June 2003, was established by the Australian Government to focus attention on this area.
The State of Knowledge Report: Air Toxics and Indoor Air Quality in Australia (2001) was prepared under the Living Cities Air Toxics Program. The report provides a compilation of existing information on air toxics and indoor air quality in Australia. It contains a Glossary that provides definitions of the technical terms used in relation to air toxics and profiles on individual air pollutants.
In recognising the potential health problems arising from the exposure to air toxics, Australia has set national benchmarks for 5 priority air toxics in ambient air: benzene, toluene, xylenes, formaldehyde and polyaromatic hydrocarbons within the National Environment Protection Measure for Air Toxics.
Biological pollutants
'Biological pollutants' are another class of pollutants. They arise from sources such as microbiological contamination, eg moulds, the skin of animals and humans and the remains and dropping of pests such as cockroaches. Biological pollutants can be airborne and can have a significant impact on indoor air quality.