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 PM2.5), 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.