Thick haze blanketed the City of London on December 5, 1952. At that time, approximately 4,000 to 8,000 Britons are estimated to have died as a result of the disaster.
The disaster that lasted for 4 days was started on December 4, 1952 afternoon. Air pollution produced by chemical plants, motor vehicles, and the chimney of the house together with the cold windless air was accompanied by thick fog.
The smog becomes progressively thicker on December 7. Even sunlight can not penetrate the thick pollution to energize British soil.