Explain the causes and result of the great smog of 1952

The Great Smog of '52 or Big Smoke was a severe air-pollution event that affected London during December 1952. A period of cold weather, combined with an anticyclone and windless conditions, collected airborne pollutants mostly from the use of coal to form a thick layer of smog over the city.

It lasted from Friday 5 to Tuesday 9 December 1952, and then dispersed quickly after a change of weather. It caused major disruption due to the effect on visibility, and even penetrated indoor areas.

It is known to be the worst air-pollution event in the history of the United Kingdom, and the most significant in terms of its effect on environmental research, government regulation, and public awareness of the relationship between air quality and health. It led to several changes in practices and regulations, including the Clean Air Act 1956.

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Answer volcanic outgassing;