3 Atmosphere | 3 Ambient air quality and other atmospheric issues | 3.6 Outlook for Australia's atmosphere
State of the Environment 2011 Committee. Australia state of the environment 2011.
Independent report to the Australian Government Minister for Sustainability, Environment, Water, Population and Communities.
Canberra: DSEWPaC, 2011.
At a glance
As a result of the success of the Montreal Protocol in controlling ozone depleting substances, the stratospheric ozone layer is expect to recover to 1980 benchmark levels by around mid-century.
The outlook for Australia’s urban air quality is generally good. However, there is clear evidence that periods of poor urban air quality (usually associated with short-lived extreme events) have serious adverse impact on human health (particularly on the health of susceptible individuals). Although levels of carbon monoxide, lead, nitrogen dioxide and sulfur dioxide have decreased over the past 10 years, ozone and particle levels have not declined, and ongoing effort will be required to secure past gains and achieve further improvements. Prospects for achieving reductions in levels of ozone and particles will be influenced by a number of factors, most notably vehicle technology, the extent of ongoing urban sprawl, the availability of reliable public transport, and the impact of climate change on urban airsheds.
There are limited Australian data on which to assess the outlook for indoor air quality. Despite this, the marked increase in government intervention to restrict areas in which smoking is permitted indoors provides grounds for suggesting an improving trend in indoor air quality, at least in commercial premises where food is prepared or consumed, in shopping malls and in public buildings.
Global observations of atmospheric levels of the major ODSs show that they peaked in the mid-1990s and have declined since then. This has led to a parallel decline in the stratospheric levels of the breakdown products of ODSs responsible for destroying ozone. The decline is expected to continue with the ongoing phase-out of these ODSs under the Montreal Protocol. As a result, the prospects for recovery of the stratospheric ozone layer to 1980 benchmark levels by around mid-century continue to be good.
Air quality in Australia’s major urban centres is generally good. Levels of carbon monoxide, lead, nitrogen dioxide and sulfur dioxide have decreased over the past two decades; however, ozone and particle levels have not declined. National health-based standards are rarely exceeded for prolonged periods, and very high levels of pollution are usually associated with short-lived extreme events such as bushfires and dust storms, which generate very high levels of particulate pollution.
Despite this broadly favourable situation, there is clear evidence that such periods of poor urban air quality have serious adverse impact on human health (particularly on the health of susceptible individuals). Research into the health effects of particles and ozone, along with pollutants such as sulfur dioxide, indicates that there is no threshold level below which they have no health effect. This means that sensitive individuals, such as asthmatics and people with respiratory or cardiovascular disease, may be affected even when air quality standards are met.6
Emissions of air pollutants from major industrial point sources are generally well controlled in all Australian jurisdictions. Their effect on urban air quality is unlikely to increase, and may well diminish with the continued uptake of cleaner technologies. Similarly, there is no evidence to suggest that urban air quality will decline due to an increase in emissions from diffuse commercial sources. As is the case with industrial sources, continuing uptake of improved practices and technologies (driven by a desire for improved efficiency, as well as by the prompting of regulators) may see a reduction in emissions of some pollutants such as VOCs.
Air pollution from domestic sources (largely particulate pollution from wood smoke) can be expected to continue to reduce air quality at the neighbourhood level in areas where wood heaters are still widely used. However, unless rising costs of domestic heating prompt a marked increase in the use of wood as a fuel, domestic premises are unlikely to be a source of significant deterioration in urban air quality.
Motor vehicles are the main diffuse source of air pollution in urban areas, and the size of the Australian fleet is continuing to grow, as are the distances travelled. Despite this and despite concerns about the effects of growing traffic congestion and continuing urban sprawl on air quality, projections to 2020 (based on a business-as-usual scenario, which does not include further tightening of emission standards) indicate a continued decline in vehicle emissions of the main air pollutants (carbon monoxide, NOx, particles and VOCs).184 The recently announced progressive introduction of tighter emission controls (Euro 5 starts in 2013 and Euro 6 in 2017) should reinforce these projected gains.182
There are reasonable grounds for optimism that reductions achieved in some urban air pollutants (carbon monoxide, nitrogen dioxide, sulfur dioxide, lead) during the past decade can be maintained or even extended. However, this is not the case with particles or the secondary, pollutant ozone. Monitoring results for these pollutants continue to show that peak ozone levels occasionally exceed the standard in some centres and that standards for particulate pollution are often exceeded for short periods in most metropolitan cities.6 Prospects of achieving significant reductions in peak levels of particles and ozone will be influenced by:
- the rate at which vehicles (particularly passenger vehicles) shift to hybrid, electric, or other forms of low-emission or no-emission propulsion
- improvements in public transport
- increased take-up of cleaner forms of production
- continuing reductions in the use of wood as a fuel for domestic heating
- urban sprawl.
Perhaps the largest influence will be the rising temperatures and more frequent extreme events associated with climate change.
The outlook for indoor air quality is difficult to assess because of the limited availability of Australian data upon which to form assessments of overall status and trend. Nevertheless, it is likely that increasing levels of restriction on smoking indoors will produce improvements in the quality of indoor air, at least in public venues and workplaces.