In December 1952 a smog, or ‘smoky fog’, event occurred that was so thick (visibility was just a few metres) and toxic it left thousands dead in London and caused transport chaos – it is even reported to have suffocated cattle to death in a field.
A period of cold, windless, anticyclonic weather led to the build-up of airborne pollutants at ground level – mostly arising from the use of coal to keep people warm during this time and carried in from industrial areas on the continent. This acted as catalysts for fog, or smog, as water clinged to the tiny particles. This formed a thick layer of smog over the city which lasted from, 5 December to 9 December 1952, dispersing as the weather changed.
It is known as a "pea-souper” due to its yellowish/green colour caused by air pollution containing soot and sulphur dioxide and was common in cities during the 19th Century until the md 20th century due to the burning of coal for heating and industrial processes. Indeed, it made up the subject of many of Claude Monet’s paintings.
Smog at this level is often lethal to vulnerable people such as the elderly, the very young and those with respiratory problems, causing skin irritations and breathing problems. At the time, 4,000 people were estimated to have died as a direct result of the smog but more recently it has been estimated that this figure could be up to 12,000, with 100,000 more becoming ill.
It has since been declared the worst air-pollution event in the UKs history and was the most significant in terms of its effect on environmental research, government regulation, and public awareness of the relationship between air quality and health. Indeed, it led to the Clean Air Act 1956, which introduced a number of measures to reduce air pollution, including introducing "smoke control areas" in some towns and cities banning the emissions of black smoke, and shifting residential sources of heat towards cleaner coals, electricity, and gas.