Pea soup, or a pea souper, also known as a black fog, killer fog or smog is a very thick and often yellowish, greenish, or blackish fog caused by air pollution that contains soot particulates and the poisonous gas sulfur dioxide. This very thick smog occurs in cities and is derived from the smoke given off by the burning of soft coal for home heating and in industrial processes. Smog of this intensity is often lethal to vulnerable people such as the elderly, the very young and those with respiratory problems. The result of these phenomena was commonly known as a London particular or London fog, which then, in a reversal of the idiom, became the name for a thick pea and ham soup.
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Historical observations
From as early as the 1200s, air pollution became increasingly prevalent, and a predominant perception in the thirteenth century was that sea-coal smoke would affect one's health. From the mid-1600s, in UK cities, especially London, the incidence of ill-health was attributed to coal smoke from domestic chimneys and industry combining with the mists and fogs of the Thames Valley. Luke Howard, a pioneer in urban climate studies, published The Climate of London in 1818–20, in which he uses the term 'city fog' and describes the heat island effect which concentrated the accumulation of smog over the city.
In 1880 Francis Albert Rollo Russell, son of the former Prime Minister Lord John Russell, published a leaflet that blamed home hearth, rather than factory, smoke for damaging the city’s important buildings, depriving vegetation of sunlight, and increasing the expense and effort of laundering clothes. Furthermore he charged the ‘perpetually present’ sulphurous smoke with increasing bronchitis and other respiratory diseases. More than 2000 Londoners had ‘literally choked to death’, he wrote, on account of ‘a want of carefulness in preventing smoke in our domestic fires’ which emitted coal smoke from ‘more than a million chimneys’ that when combined with the prolonged fogs of late January and early February 1880, fatally aggravated pre-existing lung conditions and was ‘more fatal than the slaughter of many a great battle’.
The most lethal incidence of this smog in London occurred in 1952 and resulted in the Clean Air Act 1956 and Clean Air Act 1968, both now repealed and consolidated into the Clean Air Act 1993 which were effective in largely removing sulphur dioxide and coal smoke, the causes of pea-soup fog, though these have been replaced by less visible pollutants that derive from vehicles in urban areas.
Origins of the term
Reference to the sources of smog, along with the earliest extant use of "pea-soup" as a descriptor, is found in a report by John Sartain published in 1820 on life as a young artist, recounting what it was like to; "...slink home through a fog as thick and as yellow as the pea-soup of the eating house; return to your painting room [...] having opened your window at going out, to find the stink of the paint rendered worse, if possible, by the entrance of the fog, which, being a compound from the effusions of gas pipes, tan yards, chimneys, dyers, blanket scourers, breweries, sugar bakers, and soap boilers, may easily be imagined not to improve the smell of a painting room!"
An 1871 New York Times article refers to "London, particularly, where the population are periodically submerged in a fog of the consistency of pea soup..." The fogs caused large numbers of deaths from respiratory problems.
Remediation
King Edward I of England banned the burning of sea-coal by proclamation in London in 1272, after its smoke became a problem. By the 17th century London's pollution had become a serious problem, still due, in particular, to the burning of cheap, readily available sea coal. John Evelyn, advisor to King Charles II, defined the problem in his pamphlet, “Fumifugium: Or, the Inconvenience of the Aer, and Smoake of London Dissipated” published in 1661, blaming coal, a “subterrany fuel” that had “a kind of virulent or arsenical vapour arising from it” for killing many. He proposed the relocation of industry out of the city and the planting of massive gardens of “odiferous flowers” to “tinge the air” and thus mask the pollution.
Clean Air Act
The worst recorded instance was the Great Smog of 1952, when 4,000 deaths were reported in the city over a couple of days, and a subsequent 8,000 related deaths, leading to the passage of the Clean Air Act 1956, which banned the use of coal for domestic fires in some urban areas. The overall death toll from that incident is now believed to be around 12,000.