The Great Smog of London

The Great Smog of '52 or Big Smoke was a severe air pollution event that affected London in 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 5th to Tuesday 9 December 1952, and then quickly dispersed after a change in the weather.
Although it caused major disruption due to the effect on visibility, and even penetrated indoor areas, it was not thought to be a significant event at the time, with London having experienced many smog events in the past, so called "pea soupers". In the following weeks however, medical reports estimated that 4,000 had died prematurely and 100,000 more were made ill due to the smog's effects on the human respiratory tract. More recent research suggests that the number of fatalities was considerably higher at around 12,000.

When a severe cold spell hit London in early December 1952, Londoners did what they usually did in such a situation; they burned more coal to heat up their homes. Then on December 5, 1952, a layer of dense fog engulfed the city and stayed for five days.

Since the smoke from the coal burning in homes, plus all of London's usual factory emissions, had been prevented from escaping into the atmosphere by an inversion, the fog and smoke combined into a rolling, thick layer of smog.

Folks didn't always worry about air quality.

Take one winter London day in 1952, as an example. Londoners fought off the cold and damp by burning cheap coal, as they often did. To their dismay, a fog trapped the coal smoke in London, creating a dense smog full of levels of sulphur dioxide, nitrogen oxides, and soot that the world had never seen before.

The stench of rotten eggs engulfed the city, and the blackness prevented commuters from driving. The smog stayed for four miserable days -- blackening faces, halting school attendance, coating building facades, and creeping indoors. As it gradually dissipated, a sigh of relief could be heard all over town.

The temperatures in London were hovering near freezing so people were burning additional quantities of coal in their fireplaces because many homes did not have central heating. On a daily basis, factories and trains burned coal for steam power. Cars and buses emitted pollutants from their exhaust pipes. In addition, the winds had shifted and pollutants from cities in Europe were being blown into London.

The convectional flow of air did not happen on December 5th, 1952. The day started out with clear skies but by the afternoon, fog rolled into London and thickened overnight. The next day, the dense fog prevented the sun from warming the ground air and making it rise. As a result, there was an air inversion whereby the dense fog was trapped in the cold and stagnant air under a layer of warm air. The entrapment of air pollutants turned the fog into murky yellow smog.