Early in December 1952, a cold fog caused Londoners to burn more coal than usual. When the resulting pollution was trapped by the dense mass of cold air, concentrations of pollutants built up dramatically. By the time it lifted, the smog had caused or advanced the deaths of thousands of people—most of whom were very young or elderly or had pre-existing respiratory problems—leading to a new focus on the dangers of air pollution. Even indoor events were cancelled during the Great Smog; why? Discuss
Source: The Free Dictionary