The Great Smog Descended on London More Than 65 Years Ago, and Took Almost as Long to Solve

A tugboat on the Thames near Tower Bridge in heavy smog, 1952.
A tugboat on the Thames near Tower Bridge in heavy smog, 1952.
Fox Photos/Hulton Archive/Getty Images

Heavy fogs have long been a part of life in London. In his novel Bleak House, Charles Dickens wrote:

“Fog everywhere. Fog up the river where it flows among green airs and meadows; fog down the river, where it rolls defiled among the tiers of shipping, and the waterside pollutions of a great (and dirty) city ... Chance people on the bridges peeping over the parapets into a nether sky of fog, with fog all round them, as if they were up in a balloon and hanging in the misty clouds.”

Yet a full 100 years after the celebrated author wrote those words, the city would become enveloped in a dangerous mix of fog and smoke—the likes of which they had never experienced, and were not prepared for. When the smog finally lifted, thousands of people were dead. And it would take nearly 65 years for scientists to pinpoint the reason for what has become known as The Great Smog of 1952, one of the deadliest environmental disasters in the history of the world.


5th December 1952: Morning traffic at Blackfriars, London almost at a standstill because of the blanket smog.
Don Price/Fox Photos/Getty Images

December 5, 1952 started out just like any other day in London, albeit a tremendously foggy one. But as the day wore on, it became clear that there was something different about the darkness that had descended on the city, which would hang there until December 9. People who were caught outside in the weather found themselves gasping for air, barely able to open their eyes from the sting the smoky atmosphere was delivering. Those who could see couldn’t see very far; as visibility dwindled to practically zero, pedestrians had trouble seeing their own feet while motorists were forced to abandon their vehicles.


Heavy smog in Piccadilly Circus, London, 6th December 1952.
Central Press/Hulton Archive/Getty Images

For several days, the city was essentially shut down. It all began with a cold front, which led more and more Londoners to crank up their coal stoves and gather around them for warmth. While the smoke from the city’s chimneys would normally disperse into the atmosphere, a lack of wind and an unfortunately timed anticyclone positioned over the city ended up trapping the smoke, which mixed with the fog and other pollutants, creating a lethal atmosphere.


A London bus makes its way along Fleet Street in heavy smog, 6th December 1952.
Edward Miller/Keystone/Hulton Archive/Getty Images

“You had this swirling,” funeral director Stan Cribb told NPR in 2002, “like somebody had set a load of car tires on fire.” Cribb, who at the time was working as a mortician’s assistant, was on his way to a wake with his uncle—who was also his boss—with a line of mourners behind them. According to NPR:

Neither man knew a catastrophe was brewing. They didn't know that a mass of stagnant air had just clamped a lid over London, trapping the smoke from millions of residential coal fires at ground level.

Cribb remembers being stunned by the blackness of the gathering fog. After a few minutes he couldn't see the curb from his spot behind the wheel. After a few more minutes, Tom Cribb got out and started walking in front of the hearse, to keep his nephew on the road. He carried a powerful hurricane lantern in one hand, but it was useless.

“It's like you were blind,” says Cribb.

When the fog finally lifted, reports estimated that at least 4000 people had been killed and 150,000 were hospitalized, though in the years since the total death toll has risen to approximately 12,000.


Mid-morning smog, as seen from the embankment at Blackfriars, London, 5th December 1952.
Monty Fresco/Topical Press Agency/Hulton Archive/Getty Images

Fans of the Netflix series The Crown will likely remember the season 1 episode in which Queen Elizabeth and then-Prime Minister Winston Churchill were forced to contend with the deadly event. (Of course, always aiming for accuracy, director Stephen Daldry told Entertainment Weekly that they weren’t about to use CGI to recreate The Great Smog. “We had to get a great, huge warehouse and fill it full of fog to create the great pea soup of 1952,” Daldry said. “We did it for real—CG didn’t look good enough for us.”)

Amazingly, it wasn't until 2016 that a global team of scientists announced that they may have finally solved the mystery of The Great Smog, and published their findings in the November 2016 issue of Proceedings of the National Academy of Sciences (PNAS).

“People have known that sulfate was a big contributor to the fog, and sulfuric acid particles were formed from sulfur dioxide released by coal burning for residential use and power plants, and other means,” Dr. Renyi Zhang, a professor at Texas A&M University and one of the paper’s lead authors, said. “But how sulfur dioxide was turned into sulfuric acid was unclear. Our results showed that this process was facilitated by nitrogen dioxide, another co-product of coal burning, and occurred initially on natural fog. Another key aspect in the conversion of sulfur dioxide to sulfate is that it produces acidic particles, which subsequently inhibits this process. Natural fog contained larger particles of several tens of micrometers in size, and the acid formed was sufficiently diluted. Evaporation of those fog particles then left smaller acidic haze particles that covered the city.”


Large numbers of people using the underground system to get around London during a period of heavy smog, which hampered transport on the roads, 8th December 1952.
Keystone/Hulton Archive/Getty Images

In addition to helping to solve a troubling environmental disaster that had confounded scientists for decades, Zhang and his colleagues’ research is also helping to determine how to best deal with similar air pollution problems today, including those faced by several cities in China, which is home to some of the world’s most polluted cities.

“The difference in China is that the haze starts from much smaller nanoparticles, and the sulfate formation process is only possible with ammonia to neutralize the particles,” Zhang said. “In China, sulfur dioxide is mainly emitted by power plants, nitrogen dioxide is from power plants and automobiles, and ammonia comes from fertilizer use and automobiles. Again, the right chemical processes have to interplay for the deadly haze to occur in China. Interestingly, while the London fog was highly acidic, contemporary Chinese haze is basically neutral.”

“The government has pledged to do all it can to reduce emissions going forward, but it will take time,” he added. “We think we have helped solve the 1952 London fog mystery and also have given China some ideas of how to improve its air quality. Reduction in emissions for nitrogen oxides and ammonia is likely effective in disrupting this sulfate formation process.”


A man guiding a London bus through thick fog with a flaming torch.
Monty Fresco/Getty Images

Though it would be hard to call it a silver lining, The Great Smog of 1952 did have one positive effect: it forced the country’s government, and its people, to become more aware of the impact their actions had on their environment. On July 5, 1956, less than four years after London was enveloped in a lethal darkness, the Queen enacted the Clean Air Act 1956, which banned the burning of pollutants across the UK.

Has An Element Ever Been Removed From the Periodic Table?

lucadp/iStock via Getty Images
lucadp/iStock via Getty Images

Barry Gehm:

Yes, didymium, or Di. It was discovered by Carl Mosander in 1841, and he named it didymium from the Greek word didymos, meaning twin, because it was almost identical to lanthanum in its properties. In 1879, a French chemist showed that Mosander’s didymium contained samarium as well as an unknown element. In 1885, Carl von Weisbach showed that the unknown element was actually two elements, which he isolated and named praseodidymium and neodidymium (although the di syllable was soon dropped). Ironically, the twin turned out to be twins.

The term didymium filter is still used to refer to welding glasses colored with a mixture of neodymium and praseodymium oxides.

One might cite as other examples various claims to have created/discovered synthetic elements. Probably the best example of this would be masurium (element 43), which a team of German chemists claimed to have discovered in columbium (now known as niobium) ore in 1925. The claim was controversial and other workers could not replicate it, but some literature from the period does list it among the elements.

In 1936, Emilio Segrè and Carlo Perrier isolated element 43 from molybdenum foil that had been used in a cyclotron; they named it technetium. Even the longest-lived isotopes of technetium have a short half-life by geological standards (millions of years) and it has only ever been found naturally in minute traces as a product of spontaneous uranium fission. For this reason, the original claim of discovery (as masurium) is almost universally regarded as erroneous.

As far as I know, in none of these cases with synthetic elements has anyone actually produced a quantity of the element that one could see and weigh that later turned out not to be an element, in contrast to the case with didymium. (In the case of masurium, for instance, the only evidence of its existence was a faint x-ray signal at a specific wavelength.)

This post originally appeared on Quora. Click here to view.

Graham Crackers Were Invented to Combat the Evils of Coffee, Alcohol, and Masturbation

tatniz/iStock via Getty Images
tatniz/iStock via Getty Images

Long before they were used to make s’mores or the tasty crust of a Key lime pie, graham crackers served a more puritanical purpose in 19th-century America. The cookies were invented by Sylvester Graham, an American Presbyterian minister whose views on food, sex, alcohol, and nutrition would seem a bit extreme to today's cracker-snackers. Much like the mayor in the movie Chocolat, Graham and his thousands of followers—dubbed Grahamites—believed it was sinful to eat decadent foods. To combat this moral decay, Graham started a diet regimen of his own.

Graham ran health retreats in the 1830s that promoted a bland diet that banned sugar and meat. According to Refinery29, Graham's views ultimately inspired veganism in America as well as the “first anti-sugar crusade.” He condemned alcohol, tobacco, spices, seasoning, butter, and "tortured" refined flour. Caffeine was also a no-no. In fact, Graham believed that coffee and tea were just as bad as tobacco, opium, or alcohol because they created a “demand for stimulation.” However, the worst vice, in Graham's opinion, was overeating. “A drunkard sometimes reaches old age; a glutton never,” he once wrote.

Graham’s austere philosophy was informed by the underlying belief that eating habits affect people’s behaviors, and vice versa. He thought certain foods were "overstimulating" and led to impure thoughts and passions, including masturbation—or “self-pollution,” as he called it—which he believed to be an epidemic that caused both blindness and insanity.

Illustration of Sylvester Graham
Library of Congress, Public Domain, Wikimedia Commons

Graham's views directly influenced Victorian-era corn flake inventor John Harvey Kellogg, who was born a year after Graham died. Like his predecessor, Kellogg also believed that meat and some flavorful foods led to sexual impulses, so he advocated for the consumption of plain foods, like cereals and nuts, instead. (Unsurprisingly, the original recipes for both corn flakes and graham crackers were free of sinful sugar.)

In one lecture, Graham told young men they could stop their minds from wandering to forbidden places if they avoided “undue excitement of the brain and stomach and intestines.” This meant swearing off improper foods and substances like tobacco, caffeine, pepper, ginger, mustard, horseradish, and peppermint. Even milk was banned because it was “too exciting and too oppressive.”

So what could Graham's followers eat? The core component of Graham’s diet was bread made of coarsely ground wheat or rye, unlike the refined white flour loaves that were sold in bakeries at that time. From this same flour emerged Graham's crackers and muffins, both of which were common breakfast foods. John Harvey Kellogg was known to have eaten the crackers and apples for breakfast, and one of his first attempts at making cereal involved soaking twice-baked cracker bits in milk overnight.

Slices of rye bread, a jug of milk, apples and ears of corn on sackcloth, wooden table
SomeMeans/iStock via Getty Images

However, Kellogg was one of the few remaining fans of Graham’s diet, which began to fall out of favor in the 1840s. At Ohio’s Oberlin College, a Grahamite was hired in 1840 to strictly enforce the school’s meal plans. One professor was fired for bringing a pepper shaker to the dining hall, and the hunger-stricken students organized a protest the following year, arguing that the Graham diet was “inadequate to the demands of the human system as at present developed.” Ultimately, the Grahamite and his tyrannical nutrition plan were kicked out.

Much like Kellogg’s corn flakes, someone else stepped in and corrupted Graham’s crackers, molding them into the edible form we now know—and, yes, love—today. In Graham’s case, it was the National Biscuit Company, which eventually became Nabisco; the company started manufacturing graham crackers in the 1880s. But Graham would likely be rolling in his grave if he knew they contained sugar and white flour—and that they're often topped with marshmallows and chocolate for a truly decadent treat.

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