In 2011, EPA Victoria monitored air quality at 15 sites across Victoria, with:

• 13 in metropolitan Melbourne (11 long-term and two short-term)
• two in Geelong
• one in the Latrobe Valley.

Port Phillip region

Air monitoring stations around Victoria

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

Table: State and national air quality objectives and goals

Air quality in 2011 was mainly affected by: 

• Local dust, smoke from bush fires and planned burning.
• 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. When not properly managed, sources such as wood heaters can have a significant local impact.
• Local sources and emissions from activities such as dust from the Brooklyn Estate.

An assessment against Victoria’s air quality objectives and goals is shown in the 2011 data tables (PDF 306 KB)

In Melbourne the general air quality was good overall.  Major impacts on air quality during the year were associated with particles from local dust and urban emissions (particularly from motor vehicles and wood heaters) that were trapped in calm, highly stable conditions.

Particles as PM₁₀ was the only pollutant measured by EPA’s air monitoring network above the Ambient Air Quality National Environment Protection Measure (AAQ NEPM) air quality standard. The 24-hour reporting standard for PM_2.5 was not exceeded. The air quality standards for nitrogen dioxide, carbon monoxide, sulfur dioxide and ozone were met on all days in 2011 (where there was sufficient data to demonstrate compliance).

Over all of the monitoring sites, 3 days were measured above the air quality standard for particles as PM₁₀. The 3 days exceeding the PM₁₀ standard in the Port Phillip Region were May 19 – Geelong South; May 20 – Geelong South and Mooroolbark; and June 1 – Alphington. All were attributed to urban sources, typically from vehicle traffic or domestic wood heaters.

For the second time, the Port Phillip Region in 2011 (2010 was the first) met the AAQ NEPM goal of not exceeding the particles as PM₁₀ air quality objective on 5 days at one monitoring site since AAQ NEPM reporting commenced in 2002.

Low visibility generally occurring for one to a few hours on a day was measured across Melbourne exceeding the standard at all sites with the highest frequency of events measured at Mooroolbark (18 days). This was a significant improvement on 2010 (36 days). The goal for visibility was not met at all sites. This was mainly caused from small particle emissions such as PM_2.5 from bushfires and/or planned burning and urban emissions.

Unlike the general air quality in Melbourne the local air quality in Brooklyn was regularly impacted by particles as PM₁₀ due to dust emissions from the local industrial estate. Targeted short term air monitoring in Brooklyn and Sunshine West designed to assess local impacts measured levels of particles as PM₁₀ above the air quality standard on 13 days during the year in Brooklyn. This was a significant improvement on 2010 (36 days) due in part to strategies put in place to reduce PM₁₀ dust emissions from the estate. One day was measured above the standard at Sunshine West.

In 2011 air toxics monitoring was conducted at residential sites in Tullamarine beside the old Tullamarine landfill. The majority of the air toxics were detected at low levels or not at all.

Tullamarine landfill community air monitoring program – Reports three and four

Also in 2011 air toxics monitoring was conducted in residential sites at residential sites surrounding the Dandenong South industrial precinct. The results show that for many substances the levels that were monitored were below detectable level. All substances at measurable levels in residential areas were less than the relevant air quality standards.

• Dandenong south air monitoring program: Report one
• Dandenong south air monitoring program: Report two

In Geelong there were two days where the levels of PM₁₀ exceeded the air quality standard attributed to local windblown dust and low visibility was measured on seven days. The air standards for ozone, nitrogen dioxide, carbon monoxide and sulfur dioxide were all met.  

In the Latrobe Valley, there were no days where the PM₁₀ air quality standard was exceeded and low visibility events measured on 13 days. This was a significant improvement on 2010 (26 low visibility days). Low visibility days were caused mainly by the accumulation of smoke from planned burns and/or agricultural burning and urban emissions, such as smoke from wood fires in the colder months. Levels of ozone, nitrogen dioxide and sulfur dioxide were measured below the air standards on all days during the year.

There was no monitoring in other rural regions in 2011.

Apart from periods of elevated levels of PM₁₀ due to impacts from fire and windblown dust, air quality has changed very little in Melbourne over the past decade. Melbourne’s air quality is considered to be relatively good for a major metropolitan centre.

Long-term trend graphs are available with the 2011 data tables (PDF 306 KB). Since 2002 the major impacts were influenced by fire generated during major bush fires in 2003, 2006, and 2009, planned burns during 2008 and 2009 and general windblown dust due to the effects of drought and the long-term drying pattern in Victoria.

For the first time since AAQ NEPM reporting commenced in 2002, the Port Phillip Region met the AAQ NEPM goal of not exceeding the particles as PM10 air quality standard on five days at one monitoring site. The increased rainfall during 2010 reduced the impacts from smoke and windblown dust, contributing to the lower levels of PM₁₀.

Further analysis of trends in compliance with the air quality goals is given in Air monitoring report 2011 – Compliance with the National Environment Protection (Ambient Air Quality) Measure (publication 1483).

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 given increasing pressures from population and economic growth and a changing climate. A comparison is presented in EPA's report on Victoria's air quality in 2006. (PDF 521KB)