Somebody (surely, not you, as that would be impossible) passed some gas, and now everyone in the room is violently waving their hands in front of their noses in a desperate attempt to escape the noxious fumes. But does performing that metacarpal dance actually reduce your exposure to seriously unpleasant scents, or is our hysterical fluttering all for naught? Let’s find out.
According to MIT scientist Alex Klotz, “Smell particles diffuse through the air — that is, they move around randomly as they get hit with air molecules. Because they move randomly, they’re as likely to move forward as they are backward, which means it takes them much further to reach distant noses than closer ones. However, air currents can move the particles much faster than diffusion, which is why hunters always want to be downwind from their prey (this is called a diffusion-advection process). When you waft the air in front of your nose, you’re essentially creating a miniature air current that can hopefully get the molecules away from your face.”
In simpler terms, theoretically speaking, the wind currents you create with your waving hands do have the potential to send disagreeable odors elsewhere.
“However,” Klotz says, “if you’re smelling something, then it likely means the scent has diffused from the source to your area, and all the air around you has a small concentration of it. In that case, wafting probably won’t work that well, because more stank will fill the void you just brushed away.”
So next time you smell something sour, rather than shaking your hands about within that plume of stench, maybe consider running as far away as humanly possible. I’m sure everyone will understand.