What causes the human nose to run in response to smell?
The human nose technically does not “run” as a response to smells. Research the sneeze instead. The fragrance molecules act as allergen. Remember that fragrance , tobacco smells, and dust have large molecules that appear invisible but can be picked up by the cilia in your nosetrils and nasal passage. After the immediate attempt of your body to expunge your lungs of this noxious particles (manifested as a sneeze), the next body defense is to “wash” away the allergens, hence the “runny” nose. What makes you allergic? Perfumes with civet cat secretions , and other musk based fragrance. alcohol based mixtures of created florals, wood smells etc. Tobacco smoke will make you cough but not make your nose runny unless you are choking because you cannot breathe.
