On-road mobile sources include cars, 4WDs, vans, trucks and buses. This is what they contribute to the air in Sydney:
a) NOx emissions
b) VOC emissions
c) PM10 emissions
d) PM2.5 emissions
Based on data from the Air Emissions Inventory for the Greater Metropolitan Region in NSW, August 2007
While trucks might seem to be obvious polluters, most motor vehicle emissions responsible for ground-level ozone can actually be attributed to passenger cars. This is because there are so many cars on the road.
Petrol-run passenger cars are responsible for 41.2 per cent of NOx and 19.9 per cent of VOC emissions in Sydney. That's more than all other vehicles combined.
Of the 23 per cent of fine particle emissions caused by motor vehicles, passenger vehicles are responsible for a third. The real concern here is diesel-run vehicles as diesel particles are more polluting than those created from burning petrol.
Motor vehicles also generate more than 60 per cent of benzene and 1,3-butadiene emissions, and more than 40 per cent of PAH (polycyclic aromatic hydrocarbon) emissions, all of which are air toxics. There has been growing international concern over exposure to air toxics near service stations and busy roads.
As part of an overall tightening of National Fuel Quality Standards, the Federal Government introduced a limit on benzene in petrol in 2006 to greatly reduce community exposure to this chemical.
However, even as vehicles and fuels continue to become cleaner, their benefits are likely be offset by:
- the older cars still on our roads
- the increasing number of cars that our growing population is buying
- the more trips and kilometres we are doing in our cars.
To change this trend we all need to change our habits.