Issues

• Climate Variability
• Enhanced Greenhouse Effect
• Ozone Depletion

• Meteorological Conditions
• Particulate Pollution
• Air Toxics
• Carbon Monoxide
• Heavy Industrial Emissions to Air
• Transport Emissions

• Commercial and Residential Indoor Air Quality

At a glance

The issue

Ozone is a naturally occurring gas and its existence in the stratosphere is vital to life on earth. The ozone layer acts as a shield, absorbing around 90% of harmful ultraviolet (UV) radiation from the sun. Human activities over the past century have increased the amount of substances that cause ozone depletion in the stratosphere. This has resulted in reduced stratospheric ozone levels and more UV radiation is now reaching the earth's surface.

This 'At a glance' section provides an overview of the issue of ozone depletion. More information and references are available in the Ozone Depletion Issue Report. There are five indicators included within the report. While no specific recommendation is presented on ozone depletion, there are several recommendations relevant to the Atmosphere Chapter.

Favourable news

• The recognition of the effect that many gases, such as halons and chlorofluorocarbons (CFCs) used in areas such as fire-fighting and refrigeration, were having on the ozone layer led to a global response to reduce production of the gases, collecting as much of the gases currently in use as possible, and finding alternatives.
   
• A program has been in place in Australia to collect and destroy the halons in use around the country. The Halon Bank has taken over 1.3 thousand tonnes of Halon-1211, and nearly 600 tonnes of Halon-1301 since 1993. Tasmania contributed to 4% and 5% of these totals respectively. The rate at which the substances are being deposited with the Halon Bank is slowing, as most users have already switched to other substances with a much lower ozone depleting potential.
   
• The Environmental Management and Pollution Control Act 1994 controls the use of ozone depleting substances (ODSs) and their sale must be reported to DPIWE as a condition of being authorised to purchase or sell them.
   
• In December 2003, the Ozone Protection Act 1989, was amended by the Australian Parliament. The amended Act is now called the Ozone Protection and Synthetic Greenhouse Gas Management Act 1989, and extends its scope in several areas. It incorporates synthetic greenhouse gases used as replacements for ozone depleting substances into the import, export and manufacturing licence system, but without any quotas or phase-outs. It empowers the Australian Government to develop national end-use controls on the purchase, sale, handling and disposal of these gases, replacing current State and Territory requirements. The amended Act also allows the Australian Government to implement the Beijing Amendment to the Montreal Protocol, banning the import and manufacture of bromochloromethane, and banning trade in certain ODS with non-Protocol countries. Further information is available from the Ozone Protection - Australian Government.
   
• The effectiveness of the reduction in use of ODSs is evident in the reduced rate of increase in atmospheric concentration of many of the gases, and the decline in concentration of some (e.g. chlorofluorocarbons CFC-11 and CFC-113).
   
• Tasmania lies in the region of the Southern Hemisphere where the first signs of ozone recovery are most likely to be detected, possibly around 2010-2015.
   

Unfavourable news

• There has been a rapid decline in the amount of ozone over the Antarctic regions since the 1970s, leading to the formation of the ozone 'hole'.
   
• Between 1998 and 2001 the ozone hole covered an area of up to 26 million km², nearly three times the area of Australia.
   
• Based on data from the Australian Dobson network (operated by the Bureau of Meteorology), since the late 1970s there have been statistically significant ozone decreases of 4% per decade at the Macquarie Island, Melbourne, Lauder and Perth sites during summer.
   
• Despite the reduction in use and emissions of ODSs, it is likely that evidence of ozone recovery will not be seen until about 2010-2015, as the various ODSs causing the decline continue to persist in the atmosphere.
   
• In the meantime, Tasmania will experience minimum ozone levels for the next 10 to 15 years.
   

Uncertain news

• There is uncertainty about the timing of the recovery of the ozone layer. The size and duration of the Antarctic ozone 'hole' was greatly reduced in 2002, but recovery of the ozone layer remains inconclusive (the 2003 ozone hole was the largest yet recorded).
   
• At this stage, collection data were unavailable for CFCs and hydrochlorofluorocarbons (HCFCs) in Tasmania.
   

• Issue Report - continued in depth