英语时差：人类嗅觉的奥秘（下）

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. 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 of 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 of getting a stronger dose of a weaker scent.