Great Smog of London

Great Smog of London

Nelson's Column during the Great Smog of 1952
Date 5 to 9 December 1952
Location London, England, United Kingdom
4000 Dead
200,000 Injured

The Great Smog of 1952, sometimes called The Big Smoke,[1] was a severe air-pollution event that affected the British capital of London in December 1952. A period of cold weather, combined with an anticyclone and windless conditions, collected airborne pollutants – mostly arising from the use of coal – to form a thick layer of smog over the city. It lasted from Friday, 5 December to Tuesday, 9 December 1952 and then dispersed quickly when the weather changed.

It caused major disruption by reducing visibility and even penetrating indoor areas, far more severe than previous smog events experienced in the past, called "pea-soupers". Government medical reports in the following weeks, however, estimated that up until 8 December, 4,000 people had died as a direct result of the smog and 100,000 more were made ill by the smog's effects on the human respiratory tract. More recent research suggests that the total number of fatalities was considerably greater, about 12,000.[2]

London had suffered from poor air quality since the 1200s,[3] which worsened in the 1600s,[4][5] but the Great Smog is known to be the worst air-pollution event in the history of the United Kingdom,[6] and the most significant in terms of its effect on environmental research, government regulation, and public awareness of the relationship between air quality and health.[2][4] It led to several changes in practices and regulations, including the Clean Air Act 1956.


Sources of pollution

Battersea Power Station, pictured in 2012

The cold weather preceding and during the Great Smog led Londoners to burn more coal than usual to keep warm. Post-war domestic coal tended to be of a relatively low-grade, sulphurous variety (economic necessity meant that better-quality "hard" coals tended to be exported), which increased the amount of sulphur dioxide in the smoke. There were also numerous coal-fired power stations in the Greater London area, including Fulham, Battersea, Bankside and Kingston upon Thames, all of which added to the pollution. According to the UK's Met Office, the following pollutants were emitted each day during the smoggy period: 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 which may have been converted to 800 tonnes of sulphuric acid.[7]

Research suggests that additional pollution-prevention systems fitted at Battersea may have worsened the air quality, reducing the output of soot at the cost of increased sulphur dioxide, though this is not certain. Additionally, there was pollution and smoke from vehicle exhaust  particularly from steam locomotives and diesel-fuelled buses, which had replaced the recently abandoned electric tram system  and from other industrial and commercial sources.[8] Prevailing winds had also blown heavily polluted air across the English Channel from industrial areas of Continental Europe.


On 4 December 1952, an anticyclone settled over a windless London, causing a temperature inversion with cold, stagnant air trapped under a layer (or "lid") of warm air.[9][10] The resultant fog, mixed with chimney smoke, particulates such as those from vehicle exhausts, and other pollutants such as sulphur dioxide, formed a persistent smog, which blanketed the capital the following day. The presence of tarry particles of soot gave the smog its yellow-black colour, hence the nickname "pea-souper".[8] The absence of significant wind prevented its dispersal and allowed an unprecedented accumulation of pollutants.


Effect on London

Although London was accustomed to heavy fogs, this one was denser and longer-lasting than any previous fog.[11] Visibility was reduced to a few metres ("It's like you were blind"[12]) making driving difficult or impossible.

Public transport ceased, apart from the London Underground; and the ambulance service stopped functioning, forcing users to transport themselves to hospital. The smog even seeped indoors, resulting in the cancellation or abandonment of concerts and film screenings as visibility decreased in large enclosed spaces, and stages and screens became harder to see from the seats.[13] Outdoor sports events were also affected.

In the inner London suburbs and away from town centres there was no disturbance by moving traffic to thin out the dense fog in the back streets. The result was that visibility could be down to a metre or so in the daytime. Walking out of doors became a matter of shuffling one's feet to feel for potential obstacles such as road curbs. This was made even worse at night since each back street lamp at the time was fitted with an incandescent light-bulb, which gave no penetrating light onto the pavement for pedestrians to see their feet, or even the lamp post. Fog-penetrating fluorescent lamps did not become widely available until later on in the 1950s. "Smog masks" were worn by those who were able to purchase them from chemists.

Near railway lines, on which "fog working" was implemented, loud explosions similar to the report of a shotgun were a common feature. The explosions were made by "detonators" – a form of large percussion cap placed on the track and activated by the wheels of trains. These devices were placed by certain signals to provide an audible warning to match the visual indication provided by the signal for the driver.

Health effects

There was no panic, as London was renowned for its fog. In the weeks that ensued, however, statistics compiled by medical services found that the fog had killed 4,000 people.[14] Most of the victims were very young or elderly, or had pre-existing respiratory problems. In February 1953, Lieutenant-Colonel Lipton suggested in the House of Commons that the fog had caused 6,000 deaths and that 25,000 more people had claimed sickness benefits in London during that period.[15]

Mortality remained elevated for months after the fog. A preliminary report, never finalised, blamed the ongoing deaths on an influenza epidemic.[2] Emerging evidence revealed that only a fraction of the deaths could be from influenza.[16] Most of the deaths were caused by respiratory tract infections, from hypoxia and as a result of mechanical obstruction of the air passages by pus arising from lung infections caused by the smog.[17][18][19] The lung infections were mainly bronchopneumonia or acute purulent bronchitis superimposed upon chronic bronchitis.[20][21]

More recent research suggests that the number of fatalities was considerably greater than contemporary estimates, at about 12,000.[2][22]

Environmental impact

The death toll formed an important impetus to modern environmentalism, and it caused a rethinking of air pollution, as the smog had demonstrated its lethal potential. New regulations were implemented, restricting the use of dirty fuels in industry and banning black smoke.

Environmental legislation since 1952, such as the City of London (Various Powers) Act 1954 and the Clean Air Acts of 1956 and 1968, led to a reduction in air pollution. Financial incentives were offered to householders to replace open coal fires with alternatives (such as installing gas fires), or for those who preferred, to burn coke instead which produces minimal smoke. Central heating (using gas, electricity, oil or permitted solid fuel) was rare in most dwellings at that time, not finding favour until the late 1960s onwards. Despite improvements, insufficient progress had been made to prevent one further smog event approximately ten years later, in early December 1962.[23]

In considering whether such an event could occur again, research has shown relationships between meteorological conditions, ambient atmospheric pollutants and specific mortalities. By comparing English local authority areas aggregated on a geographical scale, a clear relationship emerges between oil combustion effluents and an excessive deaths certified as caused by pneumonia due to a directly toxic acute lung injury, a finding concordant with deaths during the London smog of 1952.[24]


Atmospheric scientists at Texas A&M University investigating the haze of polluted air in Beijing realized their research led to a possible cause for the London event in 1952. "By examining conditions in China and experimenting in a lab, the scientists suggest that a combination of weather patterns and chemistry could have caused London's fog to turn into a haze of concentrated sulfuric acid." [25]

Even though research is pointing this direction, the two events are not the exact same. In China, the combination of nitrous dioxide and sulfur dioxide, both produced by burning coal, with a humid atmosphere created sulfates which made the atmosphere extremely acidic. However, ammonia from agricultural activity neutralizes the acid.

It is theorized in London in 1952 that the nitrous dioxide and sulfur dioxide combined with fog rather than humidity. This means larger droplets of water diluted the acid which inhibited the reaction to stop neutralization. Sunrise burned off the fog leaving sulfuric acid droplets which consequently killed citizens.

In popular culture

The Great Smog served as the basis of an episode titled "Forog" of The Goon Show (series 5, episode 13), which aired on 21 December 1954.[26]

The Great Smog was a central plot line in season 1, episode 4 of the Netflix series The Crown (released in November 2016).[27][28]

See also


  1. Davis, DL; Bell, ML; Fletcher, T (2002). "A look back at the London smog of 1952 and the half century since". Environmental Health Perspectives. 110: A734–5. doi:10.1289/ehp.110-a734. PMC 1241116Freely accessible. PMID 12501843.
  2. 1 2 3 4 Bell, M.L.; Davis, D.L. & Fletcher, T. (2004). "A Retrospective Assessment of Mortality from the London Smog Episode of 1952: The Role of Influenza and Pollution". Environ Health Perspect. 112 (1; January): 6–8. doi:10.1289/ehp.6539. PMC 1241789Freely accessible. PMID 14698923.
  3. Brimblecombe, Peter (1976). "Attitudes and Responses Towards Air Pollution in Medieval England". Journal of the Air Pollution Control Association. 26 (10): 941–945. doi:10.1080/00022470.1976.10470341.
  4. 1 2 Evelyn, John; Pegge, Samuel, 1704-1796, (ed.) (1661), Fumifugium, Printed by W. Godbid, retrieved 5 May 2016
  5. Graunt, John, 1620-1674; Petty, William, Sir, 1623-1687 (1662), Natural and political observations mentioned in a following index, and made upon the bills of mortality [microform] / by John Graunt ... ; with reference to the government, religion, trade, growth, ayre, diseases, and the several changes of the said city, Printed by Tho. Roycroft for John Martin, James Allestry, and Tho. Dicas
  6. McKie, Robin & Townsend, Mark. Great Smog is history, but foul air still kills (The Observer, 24 November 2002).
  7. "The Great Smog of 1952". Retrieved 12 October 2014.
  8. 1 2 Mason, Nigel; Hughes, Peter; Mc Mllan, Randall. Introduction to environmental physics (CRC, 2001), pp. 112–113.
  9. "Atmosphere, Climate & Environment Information Programme". 4 December 1952. Retrieved 30 June 2010.
  10. "Met Office Education: Teens – Case Studies – The Great Smog". Retrieved 30 June 2010.
  11. Greater London Authority. 50 Years On: The struggle for air quality in London since the great smog of December 1952.
  12. Nielson, John. "The Killer Fog of '52". NPR. Retrieved 14 December 2013.
  13. "London fog clears after days of chaos". Retrieved 7 December 2014.
  14. "The Great Smog of 1952". Retrieved 17 August 2008.
  15. "Coal: Nutty slack". Commons Sitting of 16 February 1953.
  16. Davis DL. 2002. When Smoke Ran Like Water. New York:Basic Books.
  17. Peters, Annette ; Döring, Angela ; Wichmann, H-Erich ; Koenig, Wolfgang (1997) 'Increased plasma viscosity during an air pollution episode: a link to mortality?' The Lancet, 1997, Vol.349(9065), pp.1582-1587
  18. Hunt, Andrew; Abraham, Jerrold L; Judson, Bret; Berry, Colin L (2003). "'Toxicologic and epidemiologic clues from the characterization of the 1952 London smog fine particulate matter in archival autopsy lung tissues'". Environmental Health Perspectives. 111 (9): 1209–1214. doi:10.1289/ehp.6114.
  19. Bell ML, Davis D. 2001. Reassessment of the lethal London fog of 1952: novel indicators of acute and chronic consequences of acute exposure to air pollution. Environ Health Perspect 109(suppl 3):389–394.
  20. Camps, Francis E (Ed.) (1976). Gradwohl's Legal Medicine (Bristol: John Wright & Sons Ltd, 3rd ed.) ISBN 0-7236-0310-3. p. 236.
  21. Andrew; Abraham, Jerrold L.; Judson, Bret; Berry, Colin L. (2003). "Toxicologic and Epidemiologic Clues from the Characterization of the 1952 London Smog Fine Particulate Matter in Archival Autopsy Lung Tissues Hunt". Environmental Health Perspectives. 111 (9): 1209–1214.
  22. Stone, R. (2002) Counting the Cost of London's Killer Smog. Science, 13 Dec 2002: Vol. 298, Issue 5601, pp. 2106-2107 doi:10.1126/science.298.5601.2106b
  23. "Choking fog spreads across Britain". BBC News. Retrieved 16 January 2015.
  24. Knox, E G (2008). "Research report Atmospheric pollutants and mortalities in English local authority areas". J Epidemiol Community Health. 62: 442–447. doi:10.1136/jech.2007.065862.
  25. Camila Domonoske. "Research On Chinese Haze Helps Crack Mystery Of London's Deadly 1952 Fog". Retrieved 23 November 2016.
  26. "Forog Goon Show script". The Goon Show Site. Retrieved 14 November 2016.
  27. Dibden, Emma (9 November 2016). "The 10 Key Moments From 'The Crown' Season One". Harpers Bazaar.
  28. Samuelson, Kate (4 November 2016). "Everything to Know About the Great Smog of 1952, as Seen on The Crown". TIME.

Further reading

External links

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