If you happened to be near the U.K.'s Department for Transport in London on April 27, 2016, you may have spotted this alarming scene:
Fortunately, it was a staged event. These were protesters, and they were perfectly safe and sound, out of harm's way. However, the crisis they're bringing to light is, unfortunately, pretty disturbing all on its own.
London has an air pollution problem, and it's putting the lives of city residents at stake.
The "die-in" protest, organized by Stop Killing Cyclists, brought 250 supporters onto the streets to demand cleaner air. Their staged deaths were meant to symbolize all the people air pollution silently kills in Britain each year — upward of 50,000, according to a bipartisan report from Parliament released this week.
Of course, a clean-air future is possible in London — especially when you remember what London used to look like.
Here are nine photos from the past that show just how far London has come in reducing air pollution:
1. This was London six decades ago.
Photo by Central Press/Hulton Archive/Getty Images.
2. Doesn't it look ... gray?
Photo by Fox Photos/Hulton Archive/Getty Images.
3. Smog, which became a big problem there in the 1950s and '60s, can certainly take the romance out of a cute stroll with a special someone...
Photo by Monty Fresco/Topical Press Agency/Getty Images.
4. ...or make a morning commute a whole lot worse than it needs to be.
Photo by Peter King/Fox Photos/Getty Images.
5. You could even say 1950s London resembles Beijing today.
Photo by Keystone/Getty Images.
6. Air pollution is definitely not an issue new to London in the 21st century. The smog there used to be much, much worse.
Photo by Edward Miller/Keystone/Hulton Archive/Getty Images.
7. In 1952, London's Great Smog killed and sickened thousands of residents in a matter of days.
Photo by Terry Fincher/Keystone/Hulton Archive/Getty Images.
8. In response to crises like that one, the country realized dramatic change was necessary.
Photo by Keystone/Getty Images.
9. Like many other Western nations at the time, the U.K. began breaking its addiction to dirty energy and prioritizing cleaner methods.
Photo by Topical Press Agency/Getty Images.
Clean Air Acts were passed in 1956 and 1968, which banned emissions of black smoke and forced regulations onto urban factories. In the decades since, clean-air technologies and higher pollution standards have helped guarantee London's worst smog days are far behind it.
Now, more than a half-century later, London has done quite a bit to clean up its act.
Photo by Dan Kitwood/Getty Images.
But as the recent protest illustrated, so much more needs to be done to keep London's air fresh and clean and make sure the city never returns to the smog-filled air of the '50s.
Because who would ever want to go back to this?
Photo by Fox Photos/Getty Images.