Description: Densely populated London suffers throughout the 19th and 20th centuries from pollution, largely due to domestic and industrial burning of coal. The name “smog” is used to describe smoky fog, in which smoke pollution becomes trapped in fog. In December 1952 “the Great Smog of London” occurs when a high-pressure weather system of bitter cold fog incites people to add even more coal to their furnaces. The smoke becomes trapped under the cold air resulting in an environmental catastrophe. Thousands of people, many of them infants and the elderly, die from respiratory illnesses. Also, a significant number of cattle are asphyxiated. In 1956 the Clean Air Act provides the legal basis for reducing smoke pollution, with the implementation of smokeless zones. It also encourages the transition to cleaner fuels, as well as to electricity and gas. The reduction of sulfur dioxide levels is also a result. The Clean Air Act of 1968 is a revision of the 1956 Act, with a key addition of regulating chimney height. In the collection are reports, papers, correspondence from the National Archive at Kew, photos from the Science Photo Library, videos and texts.