Great Smog Of London

Great Smog of London, also called Great Smog of 1952, lethal smog that covered the city of London for five days, from December 5 to December 9, in 1952. It was caused by a combination of industrial pollution and high-pressure weather conditions. The smoke and fog brought London to a near standstill and resulted in thousands of deaths. Its consequences prompted Parliament to pass the Clean Air Act four years later, which marked a turning point in the history of environmentalism.