History: Great Smog Of '52, London, England, United Kingdom

On 4 December 1952, an anticyclone settled over a windless London, causing a temperature inversion with cold, stagnant air trapped under a layer (or "lid") of warm air. The resultant fog, mixed with chimney smoke, particulates such as those from vehicle exhausts, and other pollutants such as sulphur dioxide, formed a persistent smog, which blanketed the capital the following day. The presence of tarry particles of soot gave the smog its yellow-black colour, hence the nickname "peasouper". The absence of significant wind prevented its dispersal and allowed an unprecedented accumulation of pollutants. When the smog eventually lifted there was a black-grey covering of slimy soot particles on all of the top surfaces out of doors. This sooty grime stayed there until a few days later when the first rains came. This soot covering was then washed off the surface of evergreen leaves, buildings and pavements, etc., into gutters and down the drains in dirty black rivulets. The pungent smell about in the atmosphere was of acrid wet soot, which made the eyes and nostrils smart for those unfortunate to be caught out in the open.
• Effect on London
Although London was accustomed to heavy fogs, this one was denser and longer-lasting than any previous fog. Visibility was reduced to a few yards ("It's like you were blind") making driving difficult or impossible.
Public transport ceased, apart from the London Underground; and the ambulance service stopped functioning, forcing sick people to transport themselves to hospital. The smog even seeped indoors, resulting in the cancellation or abandonment of concerts and film screenings as visibility decreased in large enclosed spaces, and stages and screens became harder to see from the seats. Outdoor sports events were also affected.