On Tuesday 9th December 1952, after five days of living in a sulfurous hell, the people of London – and those who did not live in London but worked there – could relax as a brisk wind from the west swept the toxic clouds away eastward and out across the North Sea.
When the fog had finally moved on it had already taken a heavy toll on the populous. About 4,000 people were known to have died as a result of the fog – but it could be many more – while a very much larger number suffered from breathing problems. It wasn’t just humans that suffered – the newspapers reported claims that cattle at Smithfield Market had been asphyxiated by the smog.
During the five days of the fog, huge amounts of impurities had been released into the atmosphere. On each day during the foggy period, it was calculated that the pollutants emitted some 1,000 tonnes of smoke particles, 2,000 tonnes of carbon dioxide, 140 tonnes of hydro-chloric acid and 14 tonnes of fluorine compounds. In addition to these, and perhaps most dangerously, some 370 tonnes of sulphur dioxide were converted into 800 tonnes of sulphuric acid!
Taking a longer view – this was nothing new
Britain has long been affected by mists and fogs but these became much more severe in the late 18th century with the onset of the Industrial Revolution. Factories belched gases and huge numbers of particles into the atmosphere, which in themselves could be poisonous. Those pollutants, however, could also act as catalysts for fog as water clung to the tiny particles to create polluted fog, or smog. To make things worse, when some of the chemicals mixed with water and air, they could create acid which could cause skin irritations and breathing problems. The worst affected area of London was usually the East End, where the density of factories and homes was greater than almost anywhere else in the capital. The area was also low-lying, making it hard for fog to disperse.
In records are reports of thick smog smelling of coal tar that blanketed London in December 1813. Recorded as lasting for several days, people claimed you could not see from one side of the street to the other. A similar fog in December 1873 saw the death rate across London rise some 40% above normal. Marked increases in death rate occurred, too, after the notable fogs of January 1880, February 1882, December 1891, December 1892 and November 1948.