Seventy years ago, London choked. For five days in December 1952, a toxic smog smothered the city. Visibility collapsed. Transport failed. Thousands died. It was not a natural disaster. It was the product of policy failure.
Out of that catastrophe came one of the most important environmental laws in UK history: the Clean Air Act 1956. It was a turning point. It showed that science, when taken seriously, can transform public health.