NH3 – ammonia – is a colorless gas with a characteristic pungent smell. Its pungence led to its occasional use as a respiratory stimulant in cases of fainting conditions. But most ammonia is used to produce fertilizers (in the form of salts), explosives, polymers, nitric acid, and many other products of the chemical industry. Ammonia is constantly forming in all of the organs and tissues of the body, most actively in the nervous tissue, liver, intestines, and muscles. But since ammonia is a toxic compound, the body performs special reactions to neutralize it.