Leaded and Unleaded Petrol

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In the early 20th century, only one type of petrol was available for use in cars.

Extracted directly from crude oil, it provided the energy needed to power an engine through combustion.

But early engines were constantly misfiring and making cars jolt.

In 1921, an early development in petroleum chemistry was pioneered by the engineer Thomas Midgley Junior.

Thomas Midgley Junior, Engineer

By experimenting with a multitude of compounds he discovered that adding a lead compound, known as TEL, made engines run smoothly and more efficiently.

TEL = tetra-ethyl lead

Leaded petrol became used worldwide, and by the 1970s the United States added roughly 200,000 tons of lead to petrol every year.

But over the next decade, serious health concerns were raised.

We now know that lead is a dangerous pollutant. It is toxic to many of our organs, and disrupts normal production of red blood cells, and long-term exposure can affect mental development in children.

Eventually, in 1983, a major study into the effects of lead resulted in leaded petrols being phased out, drastically reducing the levels of toxic lead in the air.

Today most countries worldwide have a total ban on leaded petrol in road vehicles.

Lead banned from petrol:
USA – 1995
UK – 2000
Africa – 2006

Midgley's efforts were not in vain.

Using his research, scientists were able to develop unleaded petrol, and incorporate other, safer compounds.

And new inventions such as the catalytic converter have helped to reduce the toxicity of even unleaded emissions.

Chemists, engineers, biologists and physicists continue to develop cleaner fuel technologies.

So that we can still experience a smooth journey by car whilst reducing the effects of petrol on our surroundings and our health.

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