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 and the Department of Environment and Primary Industries (now the Department of Environment, Land, Water and Planning) have recently reviewed the Environment Protection (Vehicle Emissions) Regulations 2003, which have been replaced with 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.