Death by smog: London's fatal four-day pea-souper

Thousands are estimated to have died after a thick polluted fog engulfed London for four days in December 1952.

The smog was so thick that visibility was just one metre.

Those with respiratory conditions, the young and the old were most vulnerable.

In response, the government passed the Clean Air Act to reduce the use of smoky fuels.

Witness speaks to Dr Brian Commins, who worked for the Air Pollution Unit set up at St. Bartholomew's hospital in London in the 1950s.

Witness: The stories of our times told by the people who were there.