While better-quality 'hard' coals (such as anthracite) tended to be exported to pay off World War II debts, post-war domestic coal tended to be of a relatively low-grade, sulphurous variety called ' nutty slack' (similar to lignite) which increased the amount of sulphur dioxide in the smoke. Background Sources of pollution Battersea Power Station in 1938Ī period of unusually cold weather preceding and during the Great Smog led Londoners to burn much more coal than usual to keep themselves warm. It led to several changes in practices and regulations, including the Clean Air Act 1956.

However, the Great Smog was many times worse than anything the city had ever experienced before: it is thought to be the worst air pollution event in the history of the United Kingdom, and the most significant for its effects on environmental research, government regulation, and public awareness of the relationship between air quality and health. The diarist John Evelyn had written about 'the inconveniencie of the aer and smoak of London ' in Fumifugium, the first book written about air pollution, in 1661. London's poor air quality had been a problem since at least the 13th century. More recent research suggests that the total number of fatalities was considerably greater, with estimates of between 10,000 and 12,000 deaths. Government medical reports in the weeks following the event estimated that up to 4,000 people had died as a direct result of the smog and 100,000 more were made ill by the smog's effects on the human respiratory tract. The smog caused major disruption by reducing visibility and even penetrating indoor areas, far more severely than previous smog events, called ' pea-soupers'. It lasted from Friday 5 December to Tuesday 9 December 1952, then dispersed quickly when the weather changed.

A period of unusually cold weather, combined with an anticyclone and windless conditions, collected airborne pollutants-mostly arising from the use of coal-to form a thick layer of smog over the city. The Great Smog of London, or Great Smog of 1952, was a severe air pollution event that affected London, England, in December 1952. 4,000 killed (1952 government estimate).

London fog 1541