London Smog refers to a severe air pollution event that primarily affected London in the mid-20th century. It was characterized by thick, dark fog caused by a combination of smoke from coal burning and fog from the humid climate. The most infamous incident occurred in December 1952, when a dense smog enveloped the city for several days, leading to thousands of respiratory-related deaths. The London Smog prompted significant public health concerns and government action. In response, the Clean Air Act of 1956 was enacted, which aimed to reduce air pollution by regulating emissions from factories and encouraging the use of cleaner fuels. This legislation marked a turning point in urban air quality management.