Morning traffic at Blackfriars, London, almost at a standstill because of the blanket smog. There had been smogs before, in every major conurbation. But London was the world's biggest city at the time and nearly all of its 8 million inhabitants used open coal fires. The blanket of cold air from the continent which became stationary over the capital caused the warm, smoke-laden air from homes and power stations to cool and fall back to Earth. It created a blanket of sulfurous smog so dense that visibility was less than half a metre

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