Motor vehicle emissions and air quality

Motor vehicles are the major source of urban air pollution. In Melbourne, motor vehicle emissions contribute the following levels of pollutants to the overall air quality:

• 80 per cent of carbon monoxide (CO)
• 60 per cent of nitrogen oxides (NOx).
• 40 per cent of volatile organic compounds (VOCs)
• 30 per cent of particulate matter (PM) - resulting in winter smog

Nitrogen oxides (NOx) and volatile organic compounds (VOCs) combine to form ozone (summer smog).

Particle pollution is a significant problem in Melbourne, both for its primary effects and for its tendency to form smog in the cooler months. The majority of motor vehicle related particulate matter originates from diesel vehicles.

Air quality trends

Despite an increase in the amount of motor vehicle use, emissions from motor vehicles have been dropping since 1990. EPA's air monitoring stations have found nitrogen dioxide (NO₂) and carbon monoxide (CO) levels to have more than halved since 1985, and the number of days the health standard for ozone is exceeded each year has decreased from a high of 18 down to almost none.

Furthermore, with the introduction of unleaded petrol the amount of airborne lead has decreased such that monitoring for this pollutant ceased in 2005.

For further information relating to air quality and motor vehicle emissions refer to EPA Publication 1025 - Review of Air Quality Near Major Roads (Adobe PDF file, 1022KB or 1MB).

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