London Smog
For hundreds of years, the mists and fogsof Britain's major cities were all too often polluted and noxious, with Londonespecially badly affected. The fogs endangered health and also posed a threatto travellers who lost their way and thus became an easy prey to robbers.Around 1807, the smoke-laden fog of the capital came to be known as a 'Londonparticular', i.e. a London characteristic. Charles Dickens used the term inBleak House (published in 1853) and provided graphic descriptions of London'sfogs in this and other novels.
The smoke-laden fog that shrouded thecapital from Friday 5 December to Tuesday 9 December 1952 brought prematuredeath to thousands and inconvenience to millions. An estimated 4,000 peopledied because of it, and cattle at Smithfield, were, the press reported,asphyxiated. Road, rail and air transport were almost brought to a standstilland a performance at the Sadler's Wells Theatre had to be suspended when fog inthe auditorium made conditions intolerable for the audience and performers.
The death toll of about 4,000 was notdisputed by the medical and other authorities, but exactly how many peopleperished as a direct result of the fog will never be known. Many who diedalready suffered from chronic respiratory or cardiovascular complaints. Withoutthe fog, they might not have died when they did. The total number of deaths inGreater London in the week ending 6 December 1952 was 2,062, which was close tonormal for the time of year. The following week, the number was 4,703. Thedeath rate peaked at 900 per day on the 8th and 9th and remained above averageuntil just before Christmas. Mortality from bronchitis and pneumonia increasedmore than sevenfold as a result of the fog.
The fog of December 1952 was by no meansthe first to bring death and inconvenience to the capital. On 27 December 1813fog was so dense that the Prince Regent, having set out for Hatfield House, wasforced to turn back at Kentish Town. The fog persisted for almost a week and onone day was so thick that the mail coach from London to Birmingham took sevenhours to reach Uxbridge. Contemporary accounts tell of the fog being so thickthat the other side of the street could not be seen. They also tell of the fogbearing a distinct smell of coal tar. After a similar fog during the week of7?13 December 1873, the death rate in the Administrative County of Londonincreased to 40 per cent 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. The worst affected area of London was usuallythe East End, where the density of factories and domestic dwellings was greaterthan almost anywhere else in the capital. The area was also low-lying, whichinhibited fog dispersal.
In early December 1952, the weather wascold, as it had been for some weeks. The weather of November 1952 had beenconsiderably colder than average, with heavy falls of snow in southern Englandtowards the end of the month. To keep warm, the people of London were burninglarge quantities of coal in their grates. Smoke was pouring from the chimneysof their houses and becoming trapped beneath the inversion of an anticyclonethat had developed over southern parts of the British Isles during the firstweek of December. Trapped, too, beneath this inversion were particles and gasesemitted from factory chimneys in the London area, along with pollution whichthe winds from the east had brought from industrial areas on the continent.
Early on 5 December in the London area, thesky was clear, winds were light and the air near the ground was moist.Accordingly, conditions were ideal for the formation of radiation fog. The skywas clear, so a net loss of long-wave radiation occurred and the ground cooled.The moist air in contact with the ground cooled to its dew-point temperatureand condensation occurred. Cool air drained katabatically into the ThamesValley. Beneath the inversion of the anticyclone, the very light wind stirredthe saturated air upwards to form a layer of fog 100?200 metres deep. Alongwith the water droplets of the fog, the atmosphere beneath the inversioncontained the smoke from innumerable chimneys in the London area and fartherafield. Elevated spots such as Hampstead Heath were above the fog and grime.From there, the hills of Surrey and Kent could be seen.
During the day on 5 December, the fog wasnot especially dense and generally possessed a dry, smoky character. Whennightfall came, however, the fog thickened. Visibility dropped to a few metres.The following day, the sun was too low in the sky to make much of an impressionon the fog. That night and on the Sunday and Monday nights, the fog againthickened. In many parts of London, it was impossible at night for pedestriansto find their way, even in familiar districts. In the Isle of Dogs, thevisibility was at times nil. The fog there was so thick that people could notsee their own feet! Even in the drier thoroughfares of central London, the fogwas exceptionally thick. Not until 9 December did it clear. In central London,the visibility remained below 500 metres continuously for 114 hours and below50 metres continuously for 48 hours. At Heathrow Airport, visibility remainedbelow ten metres for almost 48 hours from the morning of 6 December.
Huge quantities of impurities were releasedinto the atmosphere during the period in question. On each day during the foggyperiod, the following amounts of pollutants were emitted: 1,000 tonnes of smokeparticles, 2,000 tonnes of carbon dioxide, 140 tonnes of hydrochloric acid and14 tonnes of fluorine compounds. In addition, and perhaps most dangerously, 370tonnes of sulphur dioxide were converted into 800 tonnes of sulphuric acid. AtLondon's County Hall, the concentration of smoke in the air increased from 0.49milligrams per cubic metre on 4 December to 4.46 on the 7th and 8th.
Legislation followed the Great Smog of 1952in the form of the City of London (Various Powers) Act of 1954 and the CleanAir Acts of 1956 and 1968. These Acts banned emissions of black smoke anddecreed that residents of urban areas and operators of factories must convertto smokeless fuels. As these residents and operators were necessarily giventime to convert, however, fogs continued to be smoky for some time after theAct of 1956 was passed. In 1962, for example, 750 Londoners died as a result ofa fog, but nothing on the scale of the 1952 Great Smog has ever occurred again.
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