The Great Smog Smothers London

On 4 December 1952, a high-pressure anticyclone settled over London, bringing motionless air and cold temperatures across the Thames Valley. As households burnt extra quantities of coal to keep warm, an atmospheric temperature inversion trapped a layer of cold air beneath a ceiling of warmer air. By the following morning, smoke escaping from domestic grates, industrial plants, and power stations could not rise into the atmosphere. The accumulating soot and gases combined with the natural fog to produce a dense, yellowish-green haze that darkened the capital and persisted for five days.

The severity of the air contamination stemmed from particular economic and industrial circumstances of the post-war era. While higher-quality hard coals were exported to help settle wartime financial obligations, British households largely burnt low-grade, highly sulphurous coal known as nutty slack. Multiple coal-fired generating facilities, including Battersea, Bankside, and Fulham, operated within the metropolitan area. The UK Met Office subsequently calculated that each day of the episode added roughly 1,000 tonnes of smoke particles, 370 tonnes of sulphur dioxide, 140 tonnes of hydrochloric acid, and 14 tonnes of fluorine compounds into the stagnant air mass.