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What Happens When You Smell?

Why does our body sniff rather than smell things?

A dog lying on the floor with it's nose in focus

Photo: flyzipper (Flickr)

Smelling something is one way we gather information.

Watch your dog next time you go for a walk — chances are it sniffs at anything that might smell interesting. People sniff, too, when they’re trying to pick up a faint odor.

Sniffing For Odor

It’s clear that sniffing helps us smell those faint odors that we wouldn’t otherwise detect, but why should a quick short inhalation make our nose any more sensitive than it is during normal breathing?

The answer has to do with the maze-like structure of your nasal passage, with the nostrils at one end and the windpipe at the other, and a lot of twists, bulges, and bones that disrupt the flow of air in and out.

What Happens When You Smell?

When you inhale gradually, most of the air follows the most direct path from your nostrils to your lungs. And only a little air makes it into the other parts of the nasal cavity.

Since most of the smell receptors are located very high up, near the brain, they are out of the main flow of air. As a result, the smell receptors don’t get a strong dose of whatever’s in the air you’re breathing.

Smell Receptors

But when you sniff — that is, when you take a short, sharp inhalation, you create turbulence inside your nasal cavity that disrupts the main flow of air and sends more of the air into the out-of-the-way parts of the nasal cavity, including the part where the smell receptors are located.

With more air passing by the smell receptors, your sense of smell becomes more perceptive to faint odors.

You don’t sniff at strong, pungent smells because a little whiff is enough, and too much could even be harmful. But sniffing is the body’s way getting a stronger dose of a weaker scent.

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