Unleaded petrol is manufactured without the addition of a substance called anti-knock, a compound containing lead that was originally put into petrol to prevent knocking in the engine and promote smooth running. Unleaded petrol is now widely used in several countries and cars are made to take unleaded petrol.
 Why should I be aware of this?
- Lead is a very dangerous pollutant. Even short term exposure to lead can affect mental development of children.
- Unleaded petrol contains certain levels of benzene and other aromatic hydrocarbons which reduce the tendency of the engine to knock. But because of these contents it is often felt that unleaded petrol increases cancer risks.
- Unleaded petrol also does not lead to the formation of corrosive elements which damage spark plugs and the exhaust system.
 Unleaded petrol and health
- People are exposed to lead by a number of sources, but vehicles are the largest sources of lead exposure in many urban areas, often accounting for more than 90 per cent of all atmospheric lead emissions. It is estimated that approximately 25% of UK’s total carbon emissions are generated by transport, with road vehicles accounting for 85% of this and passenger cars generating about half of all carbon emitted by the transport sector.
- Children exposed to lead are known to show a decline in their intellectual performances and IQ levels. Adults exposed to atmospheric lead are also found to suffer from increase in blood pressure which leads to hypertension, heart attacks and premature death.
- Leaded petrol exhaust fumes not only pollute the air we breathe with microscopic lead particles (amongst other pollutants), they also add to the lead content of household dust, soil and ceiling void dust in our homes.
 All about unleaded petrol
Unleaded petrol, by allowing the introduction of catalytic converters, has made the single most effective contribution to cleaning up air pollution. Its introduction has also significantly reduced total lead emissions as leaded petrol is phased out around the world.
Exhaust fumes are made to pass through a platinum mesh, which works as the catalytic converter, before it is passed through the exhaust pipe for release into the atmosphere. The lead and platinum reaction prevents the harmful chemicals from breaking down into emission material.
 Benefits of unleaded petrol
- Various studies have documented that the use of unleaded gasoline increases the lifespan of exhaust systems and reduces engine wear.
- Unleaded gasoline increases fuel efficiency as well, due to its higher energy content.
- Unleaded cars produce less dioxins and related compounds, recognized as being highly toxic compounds.
8 Its use does not release lead compounds into the atmosphere from exhaust fumes.
 Special functions of unleaded petrol
- Two-strokes work better
Lead deposits left by leaded petrol on spark plugs cause misfiring. Also, most of the small and two stroke engines are built to function with unleaded petrol.
- More benzene in unleaded
Lead additive to boost octane is an added component. The levels of benzene, aromatics and other components are otherwise similar to those in regular unleaded petrol.
- Unleaded does not require a catalyst
Use of unleaded petrol in a vehicle without a catalyst will have the same emissions as they would if run on leaded petrol. But in such cases the lead emissions will not be generated.
- Controlled air: fuel ratio
Catalysts start operating after 3-5 minutes on reaching their correct operating temperature. Air: fuel ratios in vehicles with catalyst are closely controlled during this period to minimize exhaust emissions. There is over 90% less exhaust emissions from vehicles with catalyst compared to those without converters over all driving cycles.
- Does not harm engine
There is no harm to engines capable of converting from leaded to unleaded.These engines do not require lead for exhaust valve seat lubrication and are satisfied by the lower octane of regular unleaded petrol
- Unleaded Petrol and Ethanol
Octane rating in ethanol is higher than in unleaded petrol. If you add 10% ethanol to unleaded petrol, it raises the octane the octane rating from 92 to 95. Further when blended with ethanol unleaded further reduces knocking and gives better engine performance.
 What can I do?
Good housekeeping and improved driving can help you drive exactly the same distance and still reduce greenhouse gas emissions by up to 40%.
- Follow servicing and tuning recommendations of the manufacturers
- Do not cross the optimum tire pressure for various loads and driving conditions.
- Maintain shock absorbers properly
- Check tires, balance your wheels and align them regularly
- Fix exhaust system problems immediately
- Keep spark plugs and battery terminals clean.
- Check daily for oil leaks.
- Check the battery, oil, brake, hydraulic fluids and radiator regularly, and top up when necessary
- Use the recommended fuel, and the correct oil for the season & driving conditions.
- Keep your car air-conditioner serviced and use only when absolutely necessary
- Park your car in the shade to reduce the load on the air-conditioner.
- Travel light
- When driving, observe speed limits and road signs. While driving remain well ahead and take plenty of time to slow down. Avoid stamping on the brake.
- Unleaded petrol
- Lead, Cars and Petrol - what you should know.
- PRESSURES ON TRANSPORT