The most dangerous visible fire factor is a flame with its high temperature and powerful thermal radiation. Elevated temperatures of air and objects pose a real threat to human life and health in a fire. Open flames and sparks are also dangerous to humans.
One of the fire hazard is low oxygen content, as the combustion process occurs with intense absorption of oxygen. Therefore, in a fire, oxygen starvation may occur. When the oxygen content in the air is 16-18%, a rapid heartbeat, a slight disturbance in the coordination of movements are observed, and the ability of thinking is slightly reduced. With 9% oxygen in the breathing zone, loss of consciousness occurs, with 6% death in minutes. It is important to know that a person does not feel oxygen starvation and cannot take action. Remote control oxygen content in fire conditions - 17%.
Fire hazard is carbon monoxide ( CO ). Under normal conditions, CO is a flammable, odorless, flammable gas. Under the influence of CO, the blood loses its ability to absorb oxygen. The maximum permissible concentration of CO is 0.1%. This causes a headache, nausea, general malaise. Inhalation of air with 0.5% carbon monoxide for 20-30 minutes leads to death. If you inhale air with a content of 1% CO , death occurs after 1-2 minutes.
Carbon dioxide CO 2 (carbon dioxide) appears as a result of complete thermal decomposition of combustible materials. It has neither color nor smell, but has a sour taste. Inhalation of air with a content of up to 6-8% CO 2 leads to rapid and deeper breathing, causes tinnitus, headache, palpitations. A person loses consciousness when inhaling a mixture of 21% oxygen and 10% СО 2. PD3 СО 2 - 6%.
CO 2 poisoning can occur when extinguishing a fire using carbon dioxide fire extinguishers (especially when the room is small), as well as when entering a building after CO 2 is fed into it by an automatic carbon dioxide fire extinguishing system.
An extremely dangerous fire hazard is smoke, as in smoke, a person loses orientation, while increasing his time in extreme conditions, including in conditions of increasing content of carbon monoxide and dioxide, increasing air temperature and thermal radiation.
Depending on the type of materials to be combusted, fumes may contain fumes of sulfuric, hydrochloric, sulfuric and other acids, sulfuric and sulfuric anhydride, hydrogen fluoride, silicon, etc. When incomplete combustion of tissues (especially wool), skin, hair, sharply smelling aldehydes are formed and ketones. In this case, the formation of cyanide compounds and sulfur-containing gases is possible. Incomplete combustion of wood produces coal (solid), methyl sleep, acetic acid, acetone, tar, carbon monoxide and dioxide, methane and other hydrocarbons (gases).
The content of hydrocyanic acid vapors in an amount of 0.01% is life-threatening, 0.027% - causes death. Fire hazards are collapsing structures, equipment, communications, buildings, structures and their flying parts.
A dangerous fire factor is the possibility of the explosion of certain combustible substances and the formation of an explosive wave, which causes the destruction of structures and human damage.