London’s 1952 smog killed thousands; four years later Britain passed a law that began ending its famous coal-filled ‘pea soupers’

On a December morning in 1952, London disappeared beneath a blanket of dirty yellow fog. Visibility fell to only a few metres in places, public transport struggled and familiar streets became difficult to navigate. The air was not simply damp and murky. It was loaded with smoke, gases and particles from thousands of chimneys, trapped close to the ground by an unusual weather pattern.