Kids: Do you smell something?
Photo: Flickr user cocolima
Whether it’s fresh-baked chocolate chip cookies or stinky sneakers, no smell lasts forever. So, what happens to smells? Where do the aromatic molecules in the air all go?
You perceive an odor when molecules of a substance leave its surface and are carried by the air into your nose. Sensory cells inside your nose interact with the molecules and stimulate nerve impulses to the brain. The brain interprets the signal – “Whew! Dirty sneakers!”
We’re constantly surrounded by these chemicals in the air – called odorants. Their levels vary all the time. It takes a certain density of odorants to get your nerve impulses to fire. How long a smell hangs around depends on many factors – its chemical characteristics, the temperature, humidity and air circulation.
If you’re outside, a strong breeze can quickly dissipate an odorant. But inside, with less natural ventilation, odorants can cling to surfaces and even minute dust particles, where they get re-circulated and redistributed. And sometimes it’s not the odor that goes away, but our ability to perceive it. When the sensory nerves in your nose are repeatedly stimulated by the same odorant, their activity eventually slows down. The result – a diminished signal to the brain.
