On the 5^th of December 1952, a thick layer of fog developed over London at temperatures near 0 ^oC. This fog persisted without decreasing during several days and a considerable worry generated among the population. That day and the following, there was a great demand of hospital beds and on the 8^th of December, hospitals around Central London emitted an emergency release, declaring that they only had beds for 85% of demand. That same day, newspapers revealed that some people had died because of the fog, since this fog carried dangerous chemical pollutants.

As appeared in one of the newspapers of the city:

"From the summit of St. Paul's Cathedral of Westminster Tower for instance the average limit of visibility was only one-half mile."