Australia has had national standards and goals for ambient air quality since 1998. The Air NEPM mandates a consistent approach to air quality monitoring, which has been applied by all states and territories, but—recognising the different legislative arrangements in each jurisdiction—does not dictate the means to be applied to achieve the goals. Performance against the standards and goals is published annually, but the single access point for these reports has not been maintained since the demise of the NEPC Service Corporation.
Responding to growing concern about particle and NOx pollution from diesel vehicles, the National Environment Protection (Diesel Vehicle Emissions) Measure was established in 2001. Unlike the Australian Design Rules (ADRs), which set standards for new petrol and diesel vehicles, the Diesel Emissions NEPM targets in-service vehicles (which are a state or territory responsibility), providing a range of strategies for governments to reduce emissions, such as smoky vehicle programs, inspection and maintenance programs, and retrofit programs.
The national standards were developed based on strong empirical evidence about the health impacts of major pollutants, but new evidence has emerged during the past 20 years. A review of the NEPM was initiated in 2005, with the final report in 2011 recommending that, because new evidence showed that many pollutants do not have a recognised threshold for adverse health effects, there should be a shift in the focus of the NEPM to minimise the risk to population health from air pollution (NEPC 2011a, 2011b). The review found that more benefit at less cost could be achieved through abatement of PM pollution than for any other pollutant, so this was set as the priority for review.
On 15 December 2015, Australia’s environment ministers agreed that the advisory standards for PM2.5 should become reporting standards and that an annual average standard for PM10 of 25 µg/m3 should be added to the existing 24-hour standard. Recognising the health advantages of lower PM standards, they also agreed to aim to lower the PM2.5 standards by 2025—from 25 to 20 µg/m3 for the 24-hour average and from 8 to 7 µg/m3 for the annual average. These changes were legislated in 2016 and are incorporated in the listing in Table ATM4. To cope better with natural events that can contribute to exceedance of the standards, the 2016 NEPM changes introduced an exceptional event rule for episodes such as the major 2009 dust storm. Other natural particles, such as those of biogenic origin from emissions in the nearby Blue Mountains, can dominate the Sydney airshed during summer (Cope et al. 2014), and can make it difficult to achieve lower standards.
The 2011 review also prompted an investigation of options for introducing an exposure reduction framework (Bawden et al. 2012), after which the NEPC supported the development of an air quality ‘exposure’ metric and methodology (NEPC 2015). This has been incorporated into the 2016 Air NEPM changes. The review by the Air NEPM Expert Working Group of standards for ozone, nitrogen dioxide and sulfur dioxide is currently under way, led by the Environment Protection Authority Victoria, and is due to report in 2018.