How many olfactory cells does a human approximately have?

Explanation

Olfaction or sense of smell is the human's detection of volatile chemicals in the air. The olfactory cells cover 2.5 cm in each nose half. Altogether, a human has around 20 million olfactory cells. The sense of smell is the first to be developed in a fetus. A dog's sense of smell is 100,000-1 million times more developed than that of a human being.