People’s bodies constantly emit compounds—substances made up of two or more chemically combined elements—through their skin and as they breathe. That fact got Jonathan Williams thinking. He’s an atmospheric chemist at the Max Planck Institute for Chemistry in Germany. He wondered whether the gases humans emit were significant enough to affect the world around us.
Williams took equipment that can detect chemicals in the air to a place with a lot of people: a soccer stadium. While he took measurements, he watched fans cheer in excitement and groan in disappointment as the match played out. Although the chemicals the crowd released collectively didn’t end up amounting to much, Williams’s observations did spark a new question: Do the gases people give off change depending on their mood?
To find out, Williams needed a place with fewer variables than a soccer stadium, whose environment was too big, open, and unpredictable. “Luckily, movie theaters are perfectly designed to test this,” says Williams. The audience sits in an enclosed space and simultaneously reacts to the same thing, so he could better control the factors that would influence his investigation.