The Toxic Fog

In December 1952, a thick yellow fog covers London for several days. Residents struggle to see a few meters ahead, transport gradually stops, and buildings disappear in dense smoke. This episode finally causes thousands of deaths and permanently transforms British environmental policies.

The Great Smog appears on December 5, 1952, in a particular meteorological context. A cold air mass blocks atmospheric layers above London while the population massively uses poor-quality domestic coal for winter heating.

Industrial smoke and combustion particles remain trapped near the ground instead of dispersing normally into the atmosphere. Very quickly, an extremely dense fog loaded with sulfur dioxide and toxic particles invades the city.

Testimonies describe visibility sometimes reduced to a few dozen centimeters. Buses gradually cease circulating, performances are interrupted, and several residents struggle even to move inside public buildings. Pollution penetrates even into enclosed spaces.

Health effects become catastrophic in the following days. Elderly people, children, and individuals already suffering from respiratory problems are particularly affected. Modern estimates attribute several thousand direct or indirect deaths to the episode. The disaster plays a decisive role in the adoption of the Clean Air Act of 1956 in the United Kingdom. The event also marks a major turning point in contemporary understanding of the health effects of large-scale urban air pollution.