Thomas Midgley and the toxic legacy of leaded fuel
Leaded petrol was around for 100 years, and the campaign against it for almost as long. Mike Sutton reveals its history
In 1921 the US automobile industry was struggling with an awkward technical problem. An internal combustion engine works best when the fuel–air mixture explodes at the optimum point in its power cycle. But premature ignition – indicated by a distinctive noise known as ‘knocking’ – reduces efficiency and damages engines. In December of that year, Thomas Midgley announced his discovery of an effective remedy for it. Midgley showed that adding traces of lead to commercial gasoline prevented knocking.
Lead’s toxicity had long been known, but Midgley and his backers insisted that leaded gasoline posed no risk to public health. Decades passed before the full consequences of this error became apparent. Today, persistent lead residues remain its enduring legacy.