The Great Smog of London was a severe air pollution event that took place in London from 5-9 December 1952.
How did the Great Smog start?
London had struggled with air quality and pollution since the 1850s and experienced incidents like the “Great Stink” arising from the polluted waters of the Thames. The city also faced prolonged periods of dense air pollution known as “pea soupers”, where emissions from factories and heating stoves created a greenish fog above the streets.
During this period, Britain had emerged as a coal production titan, contributing a quarter of the world’s total coal output. Despite shifts to oil during the First and Second World Wars, the British reliance on coal persisted, particularly for heating homes. However, post-war reconstruction prompted debates about the regulation of home coal usage. Despite this, there were minimal regulations in place.
The events leading to the Great Smog unfolded as Londoners, combating the cold winter of December 1952, intensified their use of fireplaces. A weather pattern, exacerbated by a high-pressure system known as an anticyclone, played a pivotal role in transforming the coal smoke into a lethal fog. On the evening of December 5, the heat and smoke from the coal fires rose into the atmosphere. Typically, these emissions would rise, cool, and disperse. However, the anticyclone stalled over London, forcing the warm, moist air towards the ground. This created a temperature inversion, a phenomenon where cold temperatures condensed water vapour into fog, trapping the emissions over the city.
The British Meteorological Office reported that the resulting fog was up to 200 meters thick. Each day, up to a thousand tons of smoke and 2,000 tons of carbon dioxide were released over the city. Simultaneously, sulfur dioxide, a byproduct of burning coal, became trapped in the atmosphere. Mixing with water particles in the fog, it transformed into sulfuric acid, shrouding the city in a haze essentially composed of acid rain.
As the Great Smog descended, chaos ensued in London. The thick fog, now blackened with pollutants, brought visibility to near zero, rendering road travel unsafe and forcing the city to shut down its public transportation system. Pedestrians on the city sidewalks found themselves virtually blind, unable to see beyond their own feet. As the weekend unfolded, the health repercussions of the smog became increasingly apparent. Hospitalizations surged by 48 per cent that week, with respiratory-related admissions more than doubling.
Despite the severity of the event, the response from the nation’s Conservative government was initially slow. Assuming it to be just another typical “pea-souper”, there was a delayed acknowledgement of the seriousness of the Great Smog. Public health authorities downplayed the effects of the polluted air, and Prime Minister Winston Churchill refrained from making any public comments on the event or its aftermath.
However, the smog proved to be unprecedented. By the time it lifted four days later, the devastating impact had already taken its toll. The government's official tally that week reported 3,000 deaths, but later research indicated that the real death toll was approximately 12,000 deaths.
Moreover, the effects of the smog extended far beyond the immediate crisis. Children exposed to the smog during their first year of life faced long-term consequences, being more likely to develop asthma. The enduring impact on public health underscored the severity of the environmental disaster and fuelled the imperative for lasting changes in air quality regulations.
The legacy of the Great Smog was manifested through environmental regulations, marking a transformative shift in public consciousness and legislative priorities. While coal smoke had long been accepted with complacency in Britain, the catastrophic events of the Great Smog prompted a significant change in public opinion. Consequently, the British government recognized the urgency of addressing air quality issues and declared clean air a legislative priority.
In 1956, the British government took a historic step by passing the world’s first national air pollution law, the Clean Air Act. This legislation targeted the outlawing of “smoke nuisances” or “dark smoke” and mandated that new furnaces emit minimal to no smoke. As a result, the concentration of coal-produced smoke in the UK plummeted.
The Clean Air Act and its subsequent amendments not only marked a turning point for the UK but also set a global precedent, inspiring other nations to address the pressing issue of air pollution through legislative means. For instance, the United States enacted its own Clean Air Act in 1970, a full 14 years after the occurrence of the Great Smog.