The Fog That Killed 12,000 People


[♪ INTRO] London is famously foggy. Sometimes that can mean a wistful stroll or
another excuse for a cuppa tea, but when fog mixes with the smoke and chemicals produced
by industry, it becomes something new: smog. And for a couple of centuries, London’s
smog could kill. Really bad smogs could kill a thousand people
in a few days, but no one did much about it until 1952, when a five-day smog in London
killed an estimated twelve thousand people. It was called The Great Smog of London, and
it helped wake up the country and the world to the dangers of unrestricted pollution. Fog is just a cloud that forms down here on
the ground, which by itself isn’t that bad; you might not be able to
see well when you’re driving, or you might not be able to
land your plane, but it’s nice. But clouds can act like sponges, forming around
and trapping whatever’s already in the air. This wasn’t a problem until
the 1200s, when a lot of London switched from wood to
coal for heating their homes. Burning coal creates soot and smoke,
which can irritate your lungs, and also creates poisons like
sulfur dioxide and carbon monoxide. Sulfur dioxide, which is a sulfur atom bonded
to two oxygen atoms, reacts with water to form sulfuric acid, which can harm your internal
organs, as you might imagine. And carbon monoxide, which is one carbon and
one oxygen, binds with the hemoglobin in your blood to stop oxygen from
getting around your body. So when London started burning coal, all the
smoke and chemicals mixed with the natural fog, and it became thicker
and darker as years passed. It wasn’t a health crisis at first, but people did complain that
the smoke smelled terrible. And this was back in the 1200s, when everything
smelled terrible already. But it was easier to keep burning coal than
to switch back to wood, so for centuries, they just accepted the occasional thick, dark,
smelly cloud hanging over the city. As you do. Things really got dangerous when the Industrial
Revolution happened in the 1700s. Because now, coal wasn’t just heating homes. It powered huge factories throughout the city,
and all that extra smoke and soot made the air in London’s fogs much darker. It became so common that a physician named
Harold Antoine Des Voeux invented the term “smog” to describe it. Really smoggy days completely blacked out
the center of the city, so that you couldn’t see more than a few meters ahead of you, even
in the middle of the day. The soot also irritated people’s lungs,
causing illnesses like bronchitis to become more common. Some people even suffocated from breathing
so much smoke or the poisons in the air. Individual smogs in 1873 and 1892 each killed
over a thousand humans and livestock. And we don’t even know how many people died
early from collecting soot in their lungs over the course of their lives. But coal kept London flourishing,
so nobody did anything to stop it. Then came The Great Smog. On December 5, 1952, a thick fog rolled in
and mixed with London’s dirty air, just like it did most winters. But this time, high-pressure
weather systems surrounded London and kept the cloud from moving on. So an especially dense, black smog stopped
on London for five miserable days. The smog was so thick that flights were grounded,
most public transportation was canceled, trains collided, and theaters
and movies stopped, because people couldn’t see
what they were watching. This is difficult to imagine, this was 1952,
not that long ago. An estimated four thousand people died in
those five awful days before the smog dissipated. A lot of them suffocated because their lungs
were inflamed from breathing in so much soot. And with sulfur dioxide from the burning coal
reacting with water vapor in the smog, Londoners also spent those five days
breathing air full of sulfuric acid. That and the smoke contributed to
respiratory and other health problems, which killed around another
eight thousand people in the following months. Ultimately, roughly one in a thousand Londoners
died because of The Great Smog. Some people argued afterward that the spike
in deaths was due to a flu epidemic, but scientists have investigated that in all sorts of ways,
and it’s really unlikely that the flu could have been anywhere near as devastating
as the smog itself. Four years later, Parliament finally passed
a Clean Air Act that dictated what kinds of fuels could
be burned within the city. It and other laws have helped rein in the
smog problem in London. But even today, London’s air pollution lowers
the life expectancy of a lot of people, and is indirectly linked to
tens of thousands of early deaths every year throughout the United Kingdom. Despite the Great Smog’s devastation,
it took a while for other industrial powerhouses to take the hint. New York City had a series of smogs in the
1960s that affected more than 16 million people, and black, soot-filled rain coated Boston
around the same time. But eventually, lawmakers
around the world stepped in. Starting in the 1970s, laws got serious about
limiting air pollution, forcing car companies to make more efficient engines, and factories
to produce fewer emissions. Because it turns out, turning air into poison,
is not a great idea. Thank you for watching this episode of
SciShow, you’re great. And a special thanks to all of our patrons
on Patreon for making it happen! If you’d like to help us make more episodes
like this, so that everybody can have them, regardless of whether they can pay,
you can go to patreon.com/scishow, and if you just want to support us by watching,
please do that at youtube.com/scishow. [♪ OUTRO]

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