In Pictures: The Great Smog of 1952
Toxic cloud

The Great Smog was due to freak weather conditions and a build-up of years of pollution. An unusually chilly November meant that to keep warm, Londoners burnt record amounts of coal, which added to the fumes belched out by factories, power stations and diesel buses.

December brought little wind and an inversion of an anticyclone, which combined to trap filthy air in a blanket over the city.

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