6 December 2012
Last updated at 11:05
Sixty years ago thick smog descended on London, contributing to the deaths of an estimated 4,000 people. The four-day "pea-souper", while worse than usual, was a familiar experience for Londoners. The legacy of the Great Smog was the Clean Air Act of 1956 which introduced a number of measures to reduce pollution. Photo by Central Press/Hulton Archive/Getty Images.