Mercury belongs to highly toxic elements (1 hazard class). In cases of high-concentrated mercury intake mercury is concentrated in internal organs such as kidney, heart, brain. Intoxication is primarily obtained through respiratory organs, it is explain by high volatility of mercury. About 80 % of inhaled mercury vapors stay in the organism. Salts and oxygen contained in blood promote mercury absorption and combustion and lead to mercury salts formation.

The concentration value of mercury vapors which may lead to serious chronic diseases is between 0.001 and 0.005 mg/m³. Contamination may be caused by 0.13 - 0,80 mg/m³ concentrations. Fatal intoxication is obtained in case of inhalation of 2.5 grams of mercury vapors. Even low mercury concentrations (hundredth and thousandth of mg/m³ lead to nervous system breakdown in case of long-time influence.
The principal symptoms are headache, nervousness, performance decrement, increased fatigability, sleep disorder, hypomnesia, apathy (mercury neurasthenia).
In some cases metallic flavor and inflammatory gum changes are registered. Catarrhal signs of higher respiratory ways appear at the same time.

Possibility of intoxication with organo-mercuric compounds is highly dangerous. These compounds are used as pesticides, conserving agents, catalytic materials. Mercury vapors MAC in atmospheric air is 0.0003 mg/m.