Cars and Air Pollution

Cars and Air Pollution The extent of the problem

Drive time, peak hour, freeway, take-away delivery, drive through....the introduction of the automobile has had a huge impact on our lifestyle and environment.

Cars may get us from A to B (and sometimes even C and D) with a minimum of fuss, but they also cause lots of pollution.

Yes, that's right. In major cities and large towns throughout the world, motor vehicles cause a wide range of air pollution problems.

What's the largest contributor to air pollution in the world?


Fossil fuel combustion, particularly as it occurs in motor vehicles, has been identified as the LARGEST contributor to air pollution in the WORLD.

In Melbourne, motor vehicles cause most of the air pollution, except during cooler months when wood fires contribute significantly.

The impact of petrol run vehicles

Not all pollution produced by cars is the same. In fact, there are two types of pollution discharged by petrol vehicles.

  1. Exhaust emissions: including dangerous gases such as carbon monoxide, oxides of nitrogen, hydrocarbons and particulates.
  2. Evaporative emissions: vapours of fuel which are released into the atmosphere, without being burnt.

Fuel vapour can be seen coming out of the car's petrol tank when you fill up at the service station, and can be reduced if we avoid spilling petrol and overfilling our cars. Properly fitted fuel caps can also stop further leakage of fuel vapours.

Oh what a year!

1975...the year colour television was first introduced to Australians, ABBA's first album hit the Oz Top 10 and a rule requiring all new cars sold in Australia to be fitted with basic anti-pollution equipment was introduced.

Even better...since January 1986, all new cars have been built with catalytic converters and have been designed to run on unleaded petrol.

The thing most motorists forget though is that, whether you use leaded or unleaded petrol, your car will still be polluting more than necessary if it is not properly tuned and maintained.

If a car is well maintained and properly tuned it is likely to emit between 9 to 25 per cent less pollution into the atmosphere than a similar, poorly maintained vehicle. In addition, well maintained cars are also more fuel you and your family have more money to spare for things other than petrol!

Smoky vehicles What exactly is a smoky vehicle?

Under Victorian guidelines, a car is only considered smoky if it emits visible smoke from its exhaust pipe for a continuous period of more than 10 seconds.

Your car is not classified as smoky if the exhaust emissions are caused by heat or the condensation of water vapour, which can occur when the car has just been started, particularly on cold days.

Smoky cars contribute far more to air pollution than well maintained cars. Anyone who has driven behind or walked near a smoky car will know, smoky car exhausts are very offensive as well as posing a risk to public health.

In certain circumstances, even well maintained vehicles can sometimes produce smoke from their exhaust. This can occur during heavy acceleration, climbing steep hills and as engine turbos and supercharges are building sufficient speed to provide enough air to burn fuel properly.

How is the smoke harmful?

Smoke is a by-product of incomplete combustion. Incomplete combustion can significantly increase the quantity of certain toxic chemicals discharged by vehicles into the air.

These chemicals can cause mild to severe irritation to the eyes, nose, throat and lungs. They can also be absorbed into the body and cause deterioration in general health. The extent of these detrimental effects on people's health is related to the length of time one is exposed to vehicle emissions, the concentration of fumes breathed and various other factors such as age and health.

For example, an EPA study into the affects of air pollution found a link between high levels of fine particles, ozone, nitrogen dioxide and carbon monoxide and an increase in the number of hospital admissions for respiratory and cardiovascular disease (EPA Publication 789).

What causes a vehicle to be smoky?

There are many reasons why a vehicle might emit continuous smoke:

  • spark plugs need replacement or cleaning
  • ignition timing needs adjustment
  • worn piston rings, pistons or cylinder bores
  • worn valve stem guides or seals
  • sump over-filled with engine oil
  • blocked air cleaner
  • faulty electronic or mechanical controls in parts such as the choke
  • poor, contaminated or incorrect density or grade of fuel
  • blocked or damaged fuel filter
  • incorrectly set or damaged fuel injectors or fuel pump
  • incorrectly set or damaged turbo or super charges.

Remember, this list is just a guide and might not be relevant to both diesel and petrol cars.

What can we do about it?

Cleaner air for Melbourne and Victoria is up to everybody, including you!

Make sure your friends and family who own cars are looking after them!

What does the future hold?

Car use is increasing every year, however, Victoria's air quality has actually been improving because of tighter controls on car emissions.

Hybrid vehicles are now available which get their energy from batteries or petrol. These cars are still uncommon, but they are pointing the way to a future with cars contributing less to air pollution.

The battle isn't over! People will need to use their cars responsibly and keep them in tip top condition so we can continue to improve matters and ensure we have nice clean air.

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