Facts About Smell



  • Smells are scent molecules which are taken into your nose by breathed-in air. A particular smell may be noticeable even when just a single scent molecule is mixed in with millions of air molecules.
  • The human nose can tell the difference between more than 10,000 different chemicals.
  • Dogs can pick up smells that are 10,000 times fainter than the ones humans are able to detect.
  • Inside the nose, scent molecules are picked up by a patch of scent-sensitive cells called the olfactory epithelium.
  • Olfactory means ‘to do with the sense of smell’.
  • The olfactory epithelium contains over 25 million receptor cells.
  • Each of the receptor cells in the olfactory epithelium has up to 20 or so scent detecting hairs called cilia.
  • When they are triggered by scent molecules, the cilia send signals to a cluster of nerves called the olfactory bulb, which then sends messages to the part of the brain that recognizes smell.
  • The part of the brain that deals with smell is closely linked to the parts that deal with memories and emotions. This may be why smells can evoke vivid memories.
  • By the age of 20, you will have lost 20% of your sense of smell. By 60, you will have lost 60% of it.