The Great Smog of ’52 or Big Smoke was a severe air-pollution event that affected London during December 1952.

A period of cold weather, combined with an anticyclone and windless conditions, collected airborne pollutants mostly from the use of coal to form a thick layer of smog over the city. It lasted from Friday 5 December to Tuesday 9 December 1952, and then dispersed quickly after a change of weather.