At a glance
Greenhouse gases (notably carbon dioxide, methane and nitrous oxide) that are not controlled under the Montreal Protocol are expected to significantly affect future stratospheric ozone levels. In the case of carbon dioxide and methane, the effect is expected to be positive, but human-sourced emissions of nitrous oxide could (in the absence of effective abatement strategies) slow the rate of recovery of stratospheric ozone levels. Should that occur, it could delay the full realisation of health benefits expected to accompany the recovery.
During the past 30 or so years, state and territory environment protection agencies (often working together with local government) have successfully employed regulatory and nonregulatory measures to greatly reduce threats to urban air quality from industrial and commercial activities. The risk of this situation changing markedly during the next decade is assessed as low, despite continuing growth of the economy. Similarly, the risk of a significant decline in local air quality due to increase in particle (wood smoke) pollution from domestic sources is assessed as low.
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, projections to 2020 indicate a continued decline in vehicle emissions of the main air pollutants (carbon monoxide, NOx, particles and volatile organic compounds [VOCs]). This positive outlook is strengthened by the Australian Government’s recent (June 2011) announcement of the progressive introduction of tighter emission-control standards, starting in 2013. Taking into account these competing factors, the risk of a marked deterioration in urban air quality over the next decade is conservatively assessed as medium.
The higher temperatures associated with climate change are expected to elevate ambient levels of VOCs, increasing the potential for ozone pollution in Australia’s larger metropolitan centres, where peak ozone levels already at times exceed national air quality standards. Climate change is also expected to affect the likelihood of bushfires, which, depending on location, can cause very serious particulate pollution in population centres. The level of risk associated with these outcomes is assessed as medium.
Rising domestic heating and cooling costs can be expected to promote better sealing of dwellings to reduce loss of heated and cooled air. This will lead to reduced air exchange rates and a deterioration in indoor air quality.