n general the term smog has become connected to a situation where visibility is significantly impaired as a result of local air pollution. This loss of visibility is generally caused by the formation of fine particles.
The term smog, a contraction of smoke and fog, was introduced in 1905 by Dr. H.A. des Vœux to describe the mixture of soot, sulfuric acid, and other pollutants in emissions from coal furnaces in London. The city has been affected by smog since the times of King Edward I (1272-1307), who was the first to try to forbid the use of coal in London. During the winter of 1952, London experienced a very severe smog event during a unusual cold spell that resulted in approximately 12,000 additional deaths in the city. This episode resulted in significant legislation to regulate and limit the underlying causes of the smog. This case highlighted the potential health impacts of smog.