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. 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. 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.