The sense of smell in humans, and in primates in general, is relatively poorly developed. Nevertheless, it’s role should not be underestimated. It is extremely important for a person, since one of the functions of the sense of smell is to prevent dangers that are invisible to other senses (sight or hearing).
With the help of the sense of smell and reaction to unpleasant odors, it is possible to prevent poisoning with gases that can enter the body through the lungs, to determine the fire that has started by the smell of smoke. Especially in order to be able to detect a gas leak by the smell, special substances mercaptans are added to the natural gas used in everyday life, which itself does not smell of anything. With the help of the sense of smell, the body signals the harmfulness of hydrogen sulfide, chlorine, and ammonia surrounding people daily; for this reason, sharp and unpleasant odors increase blood pressure and accelerate the heartbeat.
It is also possible to control the quality of food consumed with the help of smell, which protects against decomposed and substandard products entering the gastrointestinal tract. A person is more sensitive to unpleasant odors because they signal danger and warn against eating rotten meat, fruits and sour milk. Therefore, the human nose immediately detects putrescine and ptomaine, which determine the smell of rotten meat, and hydrogen sulfide (the smell of rotten eggs) is detected by the olfactory organs in concentrations hundreds of times lower than those that pose a threat to health.
Thus, the sense of smell gives the human body the ability to perceive stimuli and receive information from the external and internal surrounding. It provides a person with a full-fledged existence in the environment, as it plays an important role in the protective function of the human body.