Shining a Light on London’s Epic 1952 Smog

London, smog London, smog
A smog that enveloped London in 1952 brought the city to a near-standstill and killed thousands of people. Fox Photos/Getty Images

It might seem like smog is a problem for developed nations: Glamorous movie stars in Los Angeles, say, stuck in fancy cars that spew out enough emissions to obscure the Hollywood sign. Of course, smog is actually a problem from Dhaka to Paris. And as Tracy V. Wilson and Holly Frey explain on this episode of Stuff You Missed In History Class, a smog that enveloped London in 1952 — long before cars were clogging freeways — wreaked havoc on the city.

The Great London Smog wasn't your typical "ugh, it looks gross out there" few days though. "This was an environmental disaster that was worse than anything that had been documented at that point," Tracy says. "At its largest, the smog was 18 miles [30 kilometers] around London, and before it was gone it had killed thousands of people."

It all started on Dec. 5, 1952, when a seemingly typical smog hung in the air during the day. But by nightfall, the smog had thickened into a heavy, sulfurous smelling fog. Normally, warm air near the ground rises up through the cold air above it, but the air in London near the ground ended up becoming cooler than the air above it on this particular day. It was a thermal inversion. All the smoke and pollution from houses, industry, you name it — was trapped near the ground. When mist formed in the layer of cold air, the sun couldn't reach the ground to begin the evaporation process. The mucky pollutants were left to hang in the air, where condensed water clung to them and created an acid fog.

And the chilly December weather didn't help matters. "It was also colder than normal, so people had to burn more coal than usual to heat their homes," says Holly. "So as the smog wore on, more and more pollution was added to this already stagnant cloud of hovering acid rain."

What resulted was five days of seemingly apocalyptic conditions. Visibility was at a meter (or about 3 feet) by Sunday, and people literally couldn't see their own feet. Driving was nearly impossible, so abandoned vehicles clogged the roads. "It went on like this for days until the wind finally came to the rescue, and it blew the fog down the Thames and out to the North Sea on Tuesday the 9th," says Tracy.

So it wasn't exactly a quick fix. First of all, a "normal" death toll for London during that time period would've been 1,852 people. During the smog days, 4,703 people died. And death tolls stayed at elevated levels for months afterward, as those with lung conditions or health problems continued to be affected by the incident.

Join Holly and Tracy as they tell you even more about the Great London Smog, its frightening conditions and the fallout on this episode of Stuff You Missed In History Class.