In 2006, EPA monitored air quality at 26 sites across Victoria, with:

• 16 in metropolitan Melbourne
• two in Geelong
• two in the Latrobe Valley
• three temporary sites in country Victoria (Ballarat, Mildura and Warrnambool for 12-month periods)
• three temporary bushfire monitoring sites (Wangaratta, Bairnsdale and Macleod).

Port Phillip region

Victoria

Air quality is assessed against the national and/or state objectives and goals shown in the table below.

Additional equipment was deployed to monitor bushfire impacts on air quality. Online data became available in December for visibility at Wangaratta and Richmond, PM₁₀ at Wangaratta, Bairnsdale and Macleod, and ozone at Wangaratta and Macleod.

EPA published advice to the public on bushfires and air quality, including how to assess the risks associated with bushfire smoke and actions to take to minimise potential health effects. Smoke advisories, including health advice, were issued through the media on 13 days in December.

In 2006, Victoria experienced severe bushfires from late November through December (and continuing into January 2007).

North-east Victoria and Gippsland were particularly affected by smoke during December. Stations in Melbourne and rural areas recorded poor visibility and high particles levels (PM₁₀) on many days in December when smoke was transported from the fires by the prevailing winds. Major fires occurred in alpine areas, northeast Victoria, Gippsland and western Victoria. Fine particles, as measured by visibility reduction, reached levels of between two and four times greater than the previously recorded highest levels at Melbourne stations.

Victoria's air quality was also impacted by bushfires in January 2006.

The bushfires in 2006 also led to unusually high levels of ozone. Bushfires emit large quantities of hydrocarbons and oxides of nitrogen, which can react to form ozone. All monitoring stations in Melbourne, Geelong and the Latrobe Valley that monitored ozone in December 2006 had days when the ozone objectives were not met. This is an unusual occurrence.

Apart from bushfires, air quality in 2006 was affected by:

• Windblown dust, often from distant sources. Windblown dust is typically coarse and tends to impact PM₁₀ more than visibility.
• Urban sources, predominantly motor vehicle and wood heater emissions accumulating in stable atmospheric conditions. These stable conditions tend to occur on calm, cold autumn/winter nights. These urban sources typically impact visibility more than PM₁₀.

Air quality in different regions in 2006 depended on how much the region was affected by bushfires.

In Melbourne there were a higher than usual number of days when the objectives for particles (both PM₁₀ and PM_2.5), visibility and ozone were not met. Particle levels were also elevated on days affected by windblown dust or when local emissions, particularly from motor vehicles and wood heaters, were trapped in calm, highly stable conditions.

The air quality objectives for nitrogen dioxide, carbon monoxide or sulfur dioxide.were met on all days in 2006.

Air toxics levels were low in 2006, and met the limits specified in the Air Toxics NEPM.

In Geelong, the number of days the objectives for PM₁₀ and visibility were not met, was approximately twice that in 2005. As Geelong was further away from the bushfires, the impacts from the bushfires were less than in Melbourne. Geelong also experienced several days where particle levels were elevated due to windblown dust. Due to these dust-affected days, Geelong had more days that did not meet the PM₁₀ objective than most stations in Melbourne.

Compared to 2005, Geelong had more days when the ozone objectives were not met. As for Melbourne, this was because of the 2006 bushfires. The objectives for nitrogen dioxide, carbon monoxide and sulfur dioxide were all met.

In the Latrobe Valley, both stations exceeded the particles (as PM₁₀), visibility and ozone objectives, with frequencies similar to those in Melbourne. Due to the bushfires, Moe and Traralgon experienced their first days not meeting the ozone objectives in over 20 years of monitoring.

The objectives for nitrogen dioxide and sulfur dioxide were met on all days.

In Ballarat bushfire smoke in early 2006 influenced visibility before monitoring ceased in August. The extent was similar to that experienced in Melbourne early in the year. Contributions of emissions from domestic wood heaters also led to poor visibility days during autumn and winter. The objectives for PM₁₀, ozone, nitrogen dioxide and carbon monoxide were met on all days. EPA has published a separate report covering the full 12 months of monitoring at Ballarat (publication 1111).

In Mildura days where the PM₁₀ objective was not met were recorded, predominantly due to windblown dust. The monitoring campaign at Mildura concluded in June. A final report covering the full monitoring campaign at Mildura is in preparation.

In Warrnambool, a 12 month period of monitoring commenced in October. Due to bushfire impacts in December, Warrnambool did not meet the visibility objective on five days and the particles (as PM₁₀) objective on three days. The ozone objectives were met at Warrnambool.

Melbourne’s air quality is better than or comparable to interstate and international cities in countries of a similar level of development to Australia. Improvements are necessary, however, to preserve Melbourne’s relatively good air quality under increasing population and economic growth and a changing climate.