Since 1998, Australia has had national ambient air quality standards (National Environment Protection Measure for Ambient Air Quality—Air NEPM), which set guideline levels for 7 key air pollutants: carbon monoxide, lead, nitrogen dioxide, ozone, particulate matter (less than 10 microns in size [PM₁₀] and 2.5 microns in size [PM_2.5]) and sulfur dioxide. Monitoring against these standards is undertaken at about 75 locations in metropolitan areas and regional towns across Australia, referred to as ‘compliance sites’.

An assessment of air quality from the worst performing (i.e. poorest air quality) of these compliance sites in each jurisdiction showed that air quality is either ‘good’ or ‘very good’ in Australian urban areas.

Levels of lead and nitrogen dioxide have declined markedly in all centres.

Particulate matter has been identified as a hazard to human health. Levels of PM₁₀ now rarely exceed the 24-hour NEPM designed for the protection of human health. However, these good results do not mean that we can be complacent about air quality in Australia as new challenges emerge. The standard for PM_2.5, which has previously been an advisory limit only, is frequently exceeded because of extreme events such as bushfires, smog and dust storms. PM_2.5 can be transported further and persist for longer in the atmosphere than PM₁₀. We do not fully understand all the processes that lead to PM_2.5 formation; thus, in the future when the PM_2.5 limit is mandatory, we will be challenged to adhere to this limit. The good news is that more air quality management stations will begin measuring PM_2.5 as part of their routine reporting obligations.

Levels of ozone have remained stable since the 2011 state of the environment report.