The Great Smog of London: what caused the 1952 crisis?

Fog was nothing new in London, though it had never been seen at such extremes before. Even as far back as the 13th century, fogs caused by burning coal were covering the city. However, the Industrial Revolution kicked things up a gear. Newly built factories pumped thousands of tonnes of acrid gases and particulate out of their chimneys, polluting the air and making smogs – a heavily polluted fog – more likely to occur. Nicknamed “peasoupers”, these yellow fogs could cause carnage when they descended upon the city. In 1873 for instance, a December fog saw the city’s death rate rocket by 40 per cent.

Fog was nothing new in London, though it had never been seen at such extremes before

There had been some paltry efforts to clean up the city’s air, but in 1952 coal fires still burned across London – and as that year’s winter was unseasonably cold, even more coal was tossed into people’s fireplaces. To make matters worse, on 5 December an anticyclone spun above London, trapping the smoke that was pouring out of the city’s chimneys and preventing it from dissipating in the atmosphere. This pressure cooker boiled over to create the most polluted smog in London’s history.

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During the five days that it blanketed the city, normal life came screeching to a halt. The city’s transportation system largely fell apart; cars littered the roads, having been abandoned by their owners. Crime rates soared, with miscreants taking advantage of the chaos.

Meanwhile, pollutants continued to pour into the atmosphere. Each day during the Great Smog, 1,000 tonnes of smoke particles, 2,000 tonnes of carbon dioxide, 140 tonnes of hydrochloric acid, 14 tonnes of fluorine compounds and 370 tonnes of sulphur dioxide were pumped into the sky. Unsurprisingly, breathing in this mix was very dangerous – and for at least 4,000 people, it soon proved fatal. A 33-year-old woman from St Pancras who previously suffered from chest pains lost her life on 9 December, with a report stating: “The fog would appear to have accelerated death, as the sudden deterioration in [her] condition was apparently unexpected by the doctor in attendance.”

How was the Great Smog fixed?

Animals were also adversely affected. The media reported that more than 100 cattle at the Smithfield Show (an agricultural fair at Earl’s Court) had to be seen by a vet as a result of breathing in the fumes, with 12 being subsequently put down. A man named LF Beccle wrote to the Ministry of Health: “I would have shared the fate of the Aberdeen Angus cattle at the Smithfield Show, for whom I had great sympathy and fellow feeling. I could not move for four days without the greatest distress... I must have been very bad indeed one night, for my wife actually held my hand and said she was sorry for me! That is proof enough that I looked as if I was going to kick the bucket.”

His letter continued: “What are our wonderful scientists doing? In an age of jet propulsion, atomic energy, and all the miracles of modern science at which we marvel, these wretched people can’t solve the problem of a lousy fog!” This sentiment was echoed across the nation, and the government was forced to act.

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In July 1956, less than four years after the Great Smog settled on London, the first Clean Air Act gained royal assent. This set out that regions of London would be smoke-free, and clamped down on coal fires both at home and in factories. The act is remembered as a key milestone in the history of environmentalism, and the city has never suffered such a terrible smog since.

This article was first published in the December 2022 issue of BBC History Revealed