Air quality

Roads and Maritime is committed to improving air quality by effectively managing the NSW roads and traffic system. We are working on a range of cleaner air initiatives to improve vehicle and fuel standards, reduce vehicle emissions and to promote greener transport alternatives.
Reducing the impact of vehicle emissions requires collaboration between government, industry, manufacturers and drivers.

Sydney's air quality

Sydney’s air quality is good by national and international standards.

Air quality in Sydney is good by national and international standards. For example, in a 2011 study of 30 major cities worldwide prepared by Environment Canada, Sydney ranked second only to Vancouver in a comparison of annual average particulate matter less than 2.5 microns (PM)2.5.

Data source: Environment Canada - International Comparison of Urban Air Quality Indicators Data

Graph - International annual average PM2.5 comparisons (2011)
International annual average PM2.5 comparisons (2011).

Please note: Caution must be taken when comparing air quality in urban areas. Differences in monitoring equipment, in the rationale behind placement of stations and in the number of stations can influence the comparability of concentrations from different urban areas.

To find out more about how Sydney's air quality compares, see:

Motor vehicles as a source of air pollution

Motor vehicles are a significant but declining source of air pollution.

Motor vehicles are a major source of human generated air pollution in Sydney, contributing 62 per cent of oxides of nitrogen (NOx) emissions, 24 per cent of volatile organic compound (VOC) emissions, and 14 per cent of PM2.5 emissions during 2008 (Figure E2; EPA, 2012).

To find out more about motor vehicle air pollution, see Reducing emissions when we drive.

Graph: Emission sources - Contribution of motor vehicle emissions to human-generated emissions in Sydney.
Contribution of motor vehicle emissions to human-generated emissions in Sydney.

To find out more about air emissions in your community, see the Environmental Protection Agency website.

Ozone is a major component of photochemical smog. It is formed in the lower atmosphere when a number of ‘precursor’ compounds - mainly oxides of nitrogen (NOx) and volatile organic compounds (VOCs) - react in warm, sunny conditions. Peak ozone levels in Sydney are therefore typically observed between November and March.

Particulate matter (PM) in the air can come directly from natural sources such as bushfires and dust storms, and also from human activities such as wood burning, quarrying and mining, motor vehicle use and industrial processes. Particle pollution is evident as the brown haze sometimes seen in the cooler months of the year.

To find out more about common air pollutants – including standards and sources – see the EPA publication Substance Information.

Newer vehicles produce significantly less emissions than older vehicles. Increasingly better fuels, improved technology and stringent emission standards have contributed to this improvement, which is likely to continue in the future. For example:

  • Cars built since 2013 emit three per cent of the oxides of nitrogen than vehicles built in 1976.
Figure E4 - Emission standards for new petrol passenger vehicles, relative to Australian Design Rule 27A
Figure E4 - Emission standards for new petrol passenger vehicles, relative to Australian Design Rule 27A
  • Diesel trucks built from 2013 emit eight per cent of the particles emitted by vehicles built in 1996.
Figure E3 - Emission standards for new heavy-duty diesel engines, relative to Euro 1
Figure E3 - Emission standards for new heavy-duty diesel engines, relative to Euro 1

As a result of the increasingly stringent emission standards and improvements in fuel quality, total exhaust emissions from motor vehicles have decreased over the past two decades, despite the increase in vehicles. They are expected to continue to fall (Figure E5), despite projected increases in the number of vehicles in use and the number of kilometres driven.

Figure E5 - Emission trends from motor vehicles in the NSW Greater Metropolitan Region
Figure E5 - Emission trends from motor vehicles in the NSW Greater Metropolitan Region

To find out more about vehicle emission standards, see Emission standards.

Reducing emissions when we drive

Roads and Maritime Services, along with other agencies, has done extensive research to improve vehicle emissions, and has developed and implemented a range of initiatives to reduce the impact of vehicle emissions on the air quality in NSW:

Managing air quality in and around tunnels

Roads and Maritime adheres to strict conditions set down by the NSW Department of Planning and Environment for the maximum allowable presence of vehicle emissions in the air both in and outside its tunnels.

Air quality monitors in and outside the tunnels constantly measure the presence of carbon monoxide, nitrogen dioxide, fine particles and visibility levels. For more information on how Roads and Maritime manages air quality in and around tunnels, see Sydney road tunnels.

In-tunnel Air Quality (Nitrogen Dioxide) Policy

In January 2016, the NSW Government introduced a formal policy for emissions compliance in new tunnel projects to protect the health and safety of tunnel users.

Find out more information on the In-tunnel Air Quality (Nitrogen Dioxide) Policy.

Assessing air quality impacts from surface roads

Recognising the contribution of motor vehicles to air pollution, Roads and Maritime developed the Tool for Roadside Air Quality (TRAQ). TRAQ assesses the potential air quality impacts and greenhouse gas emissions from vehicles using a new or existing roadway.

Find out more information about Assessing air quality impacts from surface roads.

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