Air quality

Victoria's air quality is generally good, but sometimes air pollution occurs at concentrations that affects the environment and human health.

Effects of air pollution on health

Air pollution can cause symptoms immediately upon exposure, such as coughing, watering eyes, difficulty breathing and angina.

It may also cause long-term harm that is more subtle. You might not realise how long-term exposure affects your health, or worsens medical conditions over time (Environment Protection Authority 2018).

Causes of poor air quality

A range of natural and human sources of air pollution affect air quality.

Primary air pollutants are directly emitted through mechanical or combustion processes.

They are measured in microns according to the size of the particles.

Examples include:

• PM10 (10 microns) in wind-blown dust from unpaved roads
• PM2.5 (2.5 microns) in smoke from bushfires, and sulfur dioxide from burning coal or diesel fuel.

Secondary air pollutants are formed from chemical reactions in the atmosphere.

Ozone, for example, is formed in sunlight from the reaction of volatile organic compounds with nitrous oxides.

Air monitoring in Victoria

Highlights from Air pollution in Victoria – a summary of the state of knowledge August 2018 (Environment Protection Authority Victoria 2018) include:

PM10 fine particles

• The higher trend in PM10 fine particles in Melbourne (2003 to 2009) occurred during a period of drought and bushfires. Since then, the number of exceedance days has decreased, excluding Brooklyn which is influenced by localised sources of dust.
• In 2017, the PM10 fine particle 24-hour standard was exceeded in Melbourne for five days - two of those days were attributed to dust and three were due to fires.

Figure 1. Number of exceedance days for PM10 standard- average for Port Phillip region

PM2.5 fine particles

• Compared with earlier years, and since 2014, the number of days exceeding the PM2.5 fine particle 24-hour standard in Melbourne has increased. This is partly due to changes in monitoring technology, with data available every day instead of once every three days.
• In 2017, the PM2.5 fine particle 24-hour standard was exceeded for 19 days - 6.5 of those days were attributed to land burns and 12.5 were due to urban sources (domestic wood heaters).

Figure 2. Number of exceedance days for PM 2.5 standard – average for Port Phillip region

Ozone (ground-level)

• High ozone concentrations are most likely to occur on days over 30°C with light winds and in the presence of precursor pollutants to react in the atmosphere.
• Long-term trends (1979 to 2018) show the peak one-hour ozone concentration at a Melbourne station for each year has decreased.

Figure 3. Peak maximum one-hour ozone concentrations for Port Phillip

• The annual average concentration of ozone is increasing.
• Predictions for hotter, drier conditions increase the risk of higher ozone concentrations in the future.

Figure 4. Long-term trend: annual average ozone concentrations for Port Phillip region

Future outlook for air quality in Victoria

While Victoria's air quality is good by international standards, and has improved significantly over recent decades, there remain challenges ahead.

Projected large population growth in Melbourne and regional centres comes with an associated increase in registered vehicles, infrastructure and industries. These all affect sources of air pollution and the population’s exposure to air pollution (Environment Protection Authority Victoria 2018).

In addition to overall population size, there will be potential changes to the proportion of groups more sensitive to air pollution. This includes people over 65 years, people with heart or lung conditions, and children under 14 years of age (Environment Protection Authority Victoria 2018).

Climate change is also predicted to affect future air quality by altering the meteorological variables that influence the development, chemical transformation, dispersion and deposition of air pollutants (Environment Protection Authority Victoria 2018).

Over the coming decades Victorians are likely to experience:

• worsening heatwaves and more frequent single days of extreme heat
• longer and harsher bushfire seasons
• increased periods of drought or drier conditions (Watts 2015).

These are all related to the changing climate, and all impact on the type and scale of exposure to air pollution (Environment Protection Authority Victoria 2018).

Extended dry conditions may also cause large-scale dust events, further reducing air quality (Environment Protection Authority Victoria 2018).

Find out more

The Environment Protection Authority’s air quality in Victoria page

References

Environment Protection Authority Victoria 2018, Air pollution in Victoria: a summary of the state of knowledge August 2018, Environment Protection Authority Victoria, Melbourne.

Watts N, Adger W, Agnolucci P, Blackstock J, Byass P, Cai W … Costello A 2015, ‘Health and climate change: policy responses to protect public health’, The Lancet, vol. 386, no. 7.