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.

The Most Successful Entertainment Production in History Might Just Surprise You

Goran Jakus Photography/iStock via Getty Images
Goran Jakus Photography/iStock via Getty Images

Last year, Marvel Studios capped off an unprecedented run of success with Avengers: Endgame, a movie promoted as the culmination of over 10 years of storytelling. The film made $2.8 billion, unseating 2009’s Avatar and knocking 1997’s Titanic down to third place. With nearly $3 billion in ticket sales, you would think Endgame would count as the most successful entertainment production of all time—be it a single movie, book, album, or video game.

It isn’t.

While it earned a staggering amount of money, Endgame is hobbled by the fact that theatrical runs last just a few weeks or months. To really roll in the dough, it helps to have a combination of high ticket prices and a show that runs almost in perpetuity. That’s why it’s another Disney production, the Broadway adaption of The Lion King, that can make a credible claim to being the most financially rewarding entertainment effort of all time. Since debuting in 1997, the stage show has grossed $9.1 billion. (The 1994 film, 2019 live action remake, and merchandising aren’t included in that total. If they were, the number rises to $11.6 billion.)

A theater sign for 'The Lion King' is pictured in New York City in March 2003
Mario Tama, Getty Images

The musical, adapted by Julie Taymor, follows the story of the animated original, with lion cub Simba learning to accept his role as king of the Serengeti Plains. It’s estimated the show has been mounted 25 times globally in nine different languages, with more than 100 million people purchasing a ticket to see it.

Does that make Endgame a distant second? Not quite. Another long-running musical, Andrew Lloyd Webber’s Phantom of the Opera, has grossed more than $6 billion since its 1988 debut. The 2013 video game Grand Theft Auto 5 cleared $6 billion in 2018. And if one were to account for inflation, 1939’s Gone with the Wind made $3.44 billion.

The Lion King does have one asterisk, however. If inflation is taken into consideration, then 1978’s arcade classic Space Invaders comes out the winner. The popular coin-op game—which was later ported over to the Atari 2600—was a smash hit. By 1983, it had made $3.8 billion. Accounting for inflation, it earned $13.9 billion. What’s even more impressive is that unlike big-ticket movies and stage shows, Space Invaders did it one quarter at a time.

16 Facts About Squirrels for Squirrel Appreciation Day

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iStock

Even if you live in a big city, you probably see wildlife on a regular basis. Namely, you're sure to run into a lot of squirrels, even in the densest urban areas. And if you happen to live on a college campus, well, you're probably overrun with them. While some people might view them as adorable, others see them as persistent pests bent on chewing on and nesting in everything in sight. But in honor of National Squirrel Appreciation Day, here are 16 reasons you should appreciate the savvy, amazing, bushy-tailed critters.

1. Squirrels can jump really, really far.

A flying squirrel soars through the air
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In one study of the tree-dwelling plantain squirrels that roam the campus of the National University of Singapore, squirrels were observed jumping almost 10 feet at a stretch. In another study with the eastern ground squirrel, one researcher observed a squirrel jumping more than 8 feet between a tree stump and a feeding platform, propelling itself 10 times the length of its body. Flying squirrels, obviously, can traverse much farther distances midair—the northern flying squirrel, for instance, can glide up to 295 feet.

2. Squirrels are very organized.

A squirrel digs in a grassy field filled with fallen leaves.
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In fact, they may be more organized than you are. A 2017 study found that eastern fox squirrels living on UC Berkeley's campus cache their nuts according to type. When given a mixture of walnuts, pecans, almonds, and hazelnuts, the squirrels took the time to hide each type of nut in a specific place. This method of "spatial chunking" may help them remember where the nuts are when they go to retrieve them later. Though the study wasn't able to determine this for sure, the study's results suggested that the squirrels may have been organizing their caches by even more subtle categories, like the size of the nuts.

3. Squirrels are also forgetful, and that forgetfulness helps trees grow.

Looking up a tree trunk at a squirrel climbing down
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Tree squirrels are one of the most important animals around when it comes to planting forests. Though they may be careful about where they bury their acorns and other nuts, they still forget about quite a few of their caches (or at least neglect to retrieve them). When they do, those acorns often sprout, resulting in more trees—and eventually, yet more acorns for the squirrels.

4. Squirrels help truffles thrive.

A man holds a truffle up for the camera.
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The squirrel digestive system also plays an important role in the survival of truffles. While above-ground mushrooms can spread their spores through the air, truffles grow below ground. Instead of relying on the air, they depend on hungry animals like squirrels to spread their spores to host plants elsewhere. The northern flying squirrel, found in forests across North America, depends largely on the buried fungi to make up its diet, and plays a major role in truffle propagation. The squirrels poop out the spores unharmed on the forest floor, allowing the fungi to take hold and form a symbiotic relationship with the tree roots it's dropped near.

5. Squirrels are one of the few mammals that can sprint down a tree head-first.

A squirrel stands on the knot of a tree trunk looking down at the ground.
iStock

You may not be too impressed when you see a squirrel running down a tree, but they're actually accomplishing a major feat. Most animals can't climb vertically down head-first, but squirrel's back ankles can rotate 180°, turning their paws all the way around to grip the tree trunk as they descend.

6. Several towns compete for the title of "Home of the White Squirrel."

A white squirrel in Olney, Illinois stands on its hind legs.
iStock

Squirrels are a more popular town mascot than you might think. Surprisingly, more than one town wants to be known as the "home of the white squirrel," including Kenton, Tennessee; Marionville, Missouri; the Canadian city of Exeter, Ontario; and Brevard, North Carolina, the location of the annual White Squirrel Festival. But Olney, Illinois may be the most intense about its high population of albino squirrels. There is a $750 fine for killing the all-white animals, and they have the legal right-of-way on roads. There's an official city count of the squirrels each year, and in 1997, realizing that local cats posed a threat to the beloved rodent residents, the city council banned residents from letting their cats run loose outdoors. In 2002, the city held a 100-Year White Squirrel Celebration, erecting a monument and holding a "squirrel blessing" by a priest. Police officers wore special squirrel-themed patches for the event.

7. Squirrels could aid in stroke research.

An illustration of different regions of the brain lighting up in blue
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Ground squirrels hibernate in the winter, and the way their brains function while they do may help scientists develop a new drug that can limit the brain damage caused by strokes. When ground squirrels hibernate, their core body temperature drops dramatically—in the case of the arctic ground squirrel, to as low as 26.7°F, possibly the lowest body temperature of any mammal on Earth. During this extra-cold hibernation, a squirrel's brain undergoes cellular changes that help its brain deal with reduced blood flow. Researchers are currently trying to develop a drug that could mimic that process in the human brain, preventing brain cells from dying when blood flow to the brain is cut off during a stroke.

8. Squirrel fur may have spread leprosy in the Middle Ages.

A woman in a fur vest with a hood faces away from the camera and stares out over the water.
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If you always warn your friends not to pet or feed squirrels because they can spread disease, put this story in your back pocket for later: They may have helped leprosy spread from Scandinavia to the UK in the 9th century. Research published in 2017 found a strain of leprosy similar to a modern variant found in squirrels in southern England in the skull of a woman who lived in England sometime between 885 and 1015 CE. The scientists suggest that the leprosy may have arrived along with Viking squirrel pelts. "It is possible that this strain of leprosy was proliferated in the South East of England by contact with highly prized squirrel pelt and meat, which was traded by the Vikings at the time this woman was alive," one of the authors told The Guardian. That may not be the most uplifting reason to appreciate squirrels, but it's hard not to admire their influence!

9. Squirrels are more powerful than hackers.

A squirrel runs across a power line.
Frederic J. Brown, AFP/Getty Images

While energy companies may worry about hackers disrupting the power grid, squirrels are actually far more powerful than cyber-whizzes when it comes to sabotaging our electricity supply. A website called Cyber Squirrel 1 documents every public record of squirrels and other animals disrupting power services dating back to 1987. It has counted more than 1100 squirrel-related outages across the world for that time period, which is no doubt a vast underestimate. In a 2016 survey of public power utilities, wildlife was the most common cause of power outages, and for most power companies, that tends to mean squirrels.

10. Squirrels can heat up their tails to ward off predators.

A ground squirrel sits with its mouth open.
David McNew, Getty Images

California ground squirrels have an interesting way of scaring off rattlesnakes. Like cats, their tails puff up when they go on the defense. A squirrel will wave its tail at a rattlesnake to convince the snake that it's a formidable opponent. Surprisingly, they whip their tails at their foes whether it's light or dark outside. Squirrels can control the blood flow to their tails to cool down or keep warm, and they use this to their advantage in a fight, pumping blood into their tails. Even if the rattlesnakes can't see the bushy tails, researchers found in 2007, they can sense the heat coming off them.

11. Squirrels help scientists determine whether a forest is healthy.

A squirrel runs down a tree trunk toward a pile of leaves.
iStock

Researchers look at tree squirrel populations to measure just how well a forest ecosystem is faring. Because they depend on their forest habitats for seeds, nesting sites, and food storage, the presence and demographics of tree squirrels in an area is a good bellwether for the health of a mature forest. Studying changes in squirrel populations can help experts determine the environmental impact of logging, fires, and other events that alter forest habitats [PDF].

12. Squirrels can lie.

A squirrel with a bushy tail stands on its hind legs.
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Gray squirrels know how to deceive. They can engage in what's called "tactical deception," a behavior previously only seen in primates, as a study in 2008 found. When they think they're being watched by someone looking to pilfer their cache of food, the researchers discovered, they will pretend to dig a hole as if burying their acorn or nut, but tuck their snack into their mouth and go bury it elsewhere.

13. Squirrels used to be America's most popular pet.

A man in a hat kisses a squirrel on the White House grounds
Harris & Ewing, Library of Congress // Public Domain

Though some states currently ban (or require permits for) keeping squirrels as pets, it was once commonplace. Warren G. Harding kept a squirrel named Pete who would sometimes show up to White House meetings and briefings, where members of Harding's cabinet would bring him nuts. But keeping a squirrel around wasn't just for world leaders—the rodent was the most popular pet in the country, according to Atlas Obscura. From the 1700s onwards, squirrels were a major fixture in the American pet landscape and were sold in pet shops. Despite Harding's love of Pete, by the time he lived in the White House in the 1920s, squirrel ownership was already on the wane, in part due to the rise of exotic animal laws.

14. The mere sight of just one squirrel could once attract a crowd.

A historical photo of nurses leaning down to feed a black squirrel
Library of Congress // Public Domain

The American cities of the 1800s weren't great places to catch a glimpse of wildlife, squirrels included. In fact, the animals were so rare that in the summer of 1856, when a gray squirrel escaped from its cage inside a downtown New York apartment building (where it was surely living as someone's pet), it merited a write-up in The New York Times. According to the paper, several hundred people gathered to gawk at the tree where the squirrel took refuge and try to coax the rodent down. In the end, a police officer had to force the crowd to disperse. The paper did not document what happened to the poor squirrel.

15. In the 19th century, squirrels were tasked with teaching compassion.

A boy doing homework with a squirrel on the table.
Hulton Archive, Getty Images

In the mid-1800s, seeking to return a little bit of nature to concrete jungles, cities began re-introducing squirrels to their urban parks. Squirrels provided a rare opportunity for city slickers to see wildlife, but they were also seen as a sort of moral compass for young boys. Observing and feeding urban squirrels was seen as a way to steer boys away from their "tendency toward cruelty," according to University of Pennsylvania historian Etienne Benson. Boy Scouts founder Ernest Thompson Seton argued in a 1914 article that cities should introduce "missionary squirrels" to cities so that boys could befriend them. He and other advocates of urban squirrels "saw [them] as opportunities for boys to establish trusting, sympathetic, and paternalistic relationships with animal others," Benson writes.

But young boys weren't the only ones that were thought to benefit from a little squirrel-feeding time. When the animals were first reintroduced to parks in the 19th century, feeding squirrels was considered an act of charity—one accessible even to those people who didn't have the means of showing charity in other realms. "Because of the presence of urban squirrels, even the least powerful members of human society could demonstrate the virtue of charity and display their own moral worth," Benson writes. "Gray squirrels helped reshape the American urban park into a site for the performance of charity and compassion for the weak." Even if you were too poor to provide any sort of charity for someone else, you could at least give back to the squirrels.

16. Squirrels used to hate tax season, too.

A colored lithograph shows men and dogs hunting squirrels in a forest.
Currier and Ives, Library of Congress // Public Domain

Though notably absent from big cities, much of the U.S. was once overrun by squirrels. The large population of gray squirrels in early Ohio caused such widespread crop destruction that people were encouraged—nay, required—to hunt them. In 1807, the Ohio General Assembly demanded that citizens not just pay their regular taxes, but add a few squirrel carcasses on top. According to the Ohio History Connection, taxpayers had to submit a minimum of 10 squirrel scalps to the town clerk each year. Tennessee had similar laws, though that state would let people pay in dead crows if they couldn't rustle up enough squirrels.

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