Car Pollution How Your Engine Pollutes

Cars and vans rely on their internal combustion engines for part of their power. This is achieved by burning fossil fuels and this is not, unfortunately, a clean process.

CO2 and the combustion chamber

Carbon dioxide (CO2) is the well-known exhaust gas. CO2 is used by plants for photosynthesis and humans produce it every time we breathe out. It is widely believed that the CO2 produced by motor transport is a contributing factor in climate change.

Combustion occurs when the fuel is burned; this in turn drives the vehicles wheels. The piston moves down and this allows air to enter the chamber. The piston then moves up and the mixture is compressed. In a petrol engine a spark ignites the mixture; in a diesel this is achieved by compression alone. The explosion creates energy but there are also waste products that exit the vehicle through the exhaust pipe.

Is CO2 the only pollutant?

No, the following pollutants are also produced by motor vehicles.

• Carbon monoxide – highly toxic, reduces the body’s ability to handle oxygen.
• Nitrogen oxides – a contributor to smog.
• Benzene – carcinogenic (any substance or agent that tends to produce a cancer).
• Sulphur dioxide – a contributor to acid rain
• Particulate matter – can increase the likelihood of blood clots.

Is every last drop of fuel burned?

No, the parts of the combustion chamber closest to the wall don’t reach the same temperature as the centre. Hydrocarbons exit the chamber in the same state as they went in. Hydrocarbons (unburned fuel) contribute to smog.

What is a particulate filter?

Modern diesel engines can have these fitted to reduce their harmful emissions. The filter traps the particles and prevents them from being released into the environment. A downside of a particulate filter is the slightly reduced fuel economy.

Inside Your Exhaust

Carbon dioxide (CO2) is the well-known exhaust gas. CO2 is used by plants for photosynthesis and humans produce it every time we breathe out. It is widely believed that the CO2 produced by motor transport is a contributing factor in climate change.

 

How does a catalyst converter help?

As the gases head away from the engine towards the exhaust a catalyst converter is a very effective way of reducing pollution, cutting out 90%. The catalyst converter will convert the harmful chemicals into something safer – carbon monoxide is converted into carbon dioxide; hydrocarbons turn into water and carbon dioxide and oxides of nitrogen are turned into nitrogen.