Vehicle emissions and air quality

Cars driving.

Motor vehicles are the major source of urban air pollution. In Melbourne in 2006, motor vehicle emissions contributed the following levels of pollutants to the overall air quality:

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

Particle emissions can build up in the air to form autumn/winter smog in the cooler months. Both diesel and petrol vehicles emit particles into the air.

Air quality trends

Despite increasing use of motor vehicles, their emissions have been dropping since 1990. EPA’s air monitoring stations have found nitrogen dioxide (NO2) and carbon monoxide (CO) levels have been steadily reducing since monitoring began. The number of summer smog days in Melbourne has decreased from 18 events per year down to about one event every two years.

Furthermore, with the introduction of unleaded petrol the amount of airborne lead has decreased so much EPA stopped monitoring for this pollutant in 2005.

Some aspects of motor vehicle emissions are expected to increase over time – these include particles from road dust, brake wear and tyre wear. These emissions increase directly with traffic volume. Fortunately these are a relatively minor source of particles in Melbourne’s air.

Although there have been major improvements over the last 30 years, motor vehicles are still a significant source of air pollution. You can help reduce pollution from your vehicle, and make a difference to air quality.

Regulating motor vehicle emissions

EPA administers the Environment Protection (Vehicle Emissions) Regulations 2013.

The Regulations aim to minimise the negative impacts on Victorians and the environment of air and noise emissions from motor vehicles and the release of petrol vapours relating to the production of petrol.

Heavy vehicles (large trucks and buses over 4.5 tonnes) are not regulated by EPA. Heavy vehicles are managed under the Heavy Vehicle National Law by the National Heavy Vehicle Regulator and are administered in Victoria by VicRoads.

Modifications to vehicle exhausts

Modifications to vehicle exhausts, including Diesel Particulate Filters (DPFs), cannot be approved by EPA. DPFs are installed to reduce the health effects of particles created during the diesel combustion cycle.

If you have concerns about your DPF, please contact your vehicle service centre for assistance. If you are concerned about a hot DPF causing ignition of dry grass, the service centre may recommend installing heat shielding. If the concern cannot be addressed by the recommended means and the vehicle requires further modifications, please contact VicRoads Vehicle Safety and Registration Services at

Page last updated on 31 Oct 2018