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Air pollution is the greatest environmental issue concerning Australians (Environmental Issues: Peoples Views and Practices (4602.0)). Poor air quality can have a number of negative impacts on both environmental and human health (EPAV 2000). For example, increases in atmospheric nitrogen oxides (oxides of nitrogen) contribute to acid rain, and exposure can lead to a fatal excessive fluid build up in the lung tissues (pulmonary oedema) in humans (NPI 2003a). This section examines both outdoor and indoor air pollution.
Indoor air pollution
Indoor air pollution is of particular concern as Australians spend up to 90% of their time inside (How Australians Use Their Time (4153.0)). However, information currently available on the level of indoor pollutants, their sources and the health effects, are not comprehensive enough to allow a confident evaluation of these issues at this stage (EA 2001a). Several research projects are currently being conducted, including the BTEX (benzene, toluene, ethylbenzene, and xylene) personal exposure monitoring study, to address these gaps in knowledge (EA 2001b).
Generally, air pollution is greater indoors than outside and several factors influence the level of air pollution build up in buildings. These include the level of ventilation and the presence of toxic substances. Newer buildings are particularly at risk of hazardous air pollution due to low ventilation rates and 'off gassing' of new building materials. 'Off gassing' refers to the releases of toxic fumes from furniture, carpets, paints, glues and sealants used in building products. These fumes are greatest in new buildings and may remain high for several months (EA 2001a).
Another major source of indoor emissions is the use of gas cookers and unflued gas heaters. As a result of studies linking these appliances to indoor air pollution, unflued gas heaters are now being systematically replaced in all New South Wales schools. Outdoor air quality can also impact on indoor air quality due to the air exchange rate which varies with climate, lifestyle and building design (EA 2001a).
Levels of air pollution
Air quality monitoring indicates that overall Australia currently has fairly good air quality. There is little evidence of air pollution problems from sulfur dioxide, nitrogen dioxide or lead in the urban areas of Australia at present. Carbon monoxide is a problem in some areas but is unlikely to be of concern in the future (Manins et al. 2001). However, the levels of particulate matter and ozone are of concern and the next section examines these two pollutants.
The factors influencing air quality vary considerably. The main factors influencing metropolitan air quality include motor vehicles and industry while air quality in regional areas is influenced by localised factors such as mining and domestic heating. As a result of these different influences the seasonal occurrence of air pollution tends to be different in different parts of Australia. For example, in Sydney one of the main air quality issues is photochemical smog (measured as surface ozone), which occurs mainly in summer. However, in Launceston (Tasmania) one of the main air quality issues is high levels of particulate matter less than ten micrometres in diameter, which occurs mainly in winter (graph 24.26).
Photochemical smog is formed by emissions of oxides of nitrogen and hydrocarbons reacting with sunlight to eventually form ozone (Australia's Environment: Issues and Trends, 2001 (4613.0)). The levels of surface ozone in major cities is of particular concern as it has been correlated with increases in mortality (EPAV 2000). Although the levels of ozone concentrations have remained fairly steady from 1999 to 2001 (table 24.27), the surface ozone exceedences are likely to become less frequent over time as older motor vehicles are phased out and are replaced by newer vehicles that are subject to more stringent emission controls. These controls set upper levels of emissions for pollutants such as sulfur dioxide and oxygenates. However, even with these controls it is possible that as vehicle usage and numbers continue to rise, the volume of emissions may lead to increasing levels of ozone (Manins et al. 2001).
The most important air quality issue for non-metropolitan areas of Australia is airborne particles (Manins et al. 2001). Fine particles of particulate matter (PM10) are particles of any substance less than ten micrometers in diameter and include sulfates, nitrates, carbon and silica (Measuring Australia's Progress (1370.0)). Particle pollution is a major health concern as it can exacerbate respiratory and cardiovascular illnesses, including bronchitis, pneumonia and asthma, leading to increased hospital admissions (Atech 2001). Particles have also been linked to the deaths of up to 2,400 people a year in Australia, carrying an associated cost of $17.2b (EA 2001c).
Fine particles mostly come from burning fossil fuels or wood but there are also a number of important natural sources of PM10 including sea salt, dust, emissions from vegetation, pollen and bushfires (NEPC 1998). The sources of particle pollution differ between areas (graph 24.28).
Particle levels are influenced by climate and topographical conditions. In warmer regions, such as Sydney and South-East Queensland dry conditions can contribute to bushfires and windblown dust. Bushfires cause the levels of fine particles to rise above the air NEPM. The peak levels of fine particulate pollution are usually around 70 microgram per cubic metre or less (Manins et al. 2001). In Armidale (New South Wales), Launceston and Canberra the use of domestic wood fires for heating in winter can lead to high levels of particles (EA 2001c) and, in 2000 in Launceston, the highest measured level was 111 micrograms per cubic metre (DPIWE 2002) (table 24.29).
All levels of government have undertaken measures to try and reduce the ambient particle levels in Australia. These measures include:
National Pollutant Inventory
The National Pollutant Inventory (NPI) is a database designed to provide the community, industry and government with information on the levels of certain pollutants emitted to the environment from industry and other sources. However, the purpose of the NPI is not to examine the direct environmental or health effects of emissions. This database provides information on the quantities of pollutants emitted as well as their source and location. The NPI currently holds emission data for close to 3,000 facilities, 32 airsheds and 29 catchments around Australia. Currently facilities estimate their own emissions annually (by completing a reporting form), with 'aggregated emissions' from households and other sources being estimated by government agencies (NPI 2002).