How many olfactory receptor cells do humans have?

In humans, olfactory receptor cells are present in very large numbers, specifically in the millions. These cells are clustered within the olfactory epithelium, a small area located in the back of the nasal cavity.12

While humans possess approximately 1,000 olfactory-type receptor genes, only about 350 of these genes encode working olfactory receptors. Each individual receptor cell expresses only one type of receptor protein, though it contains thousands of that specific protein on the membrane of its cilia. Because each cell is limited to a single type of receptor, the body maintains large numbers of these cells to ensure that odor molecules can successfully encounter a matching receptor.13