Smoke is produced by flame; it is sometimes seen as a mixture of small and large particles of grey and black soot, and products of incomplete combustion of the fuel being burnt.
Smoke contains a cocktail of very toxic chemicals and gases. Carbon monoxide (CO) and Hydrogen Cyanide are two of the more common gases which if inhaled can be very harmful if not fatal to human beings.
Hydrogen cyanide is some 20 times more toxic than CO and is produced by burning some common materials found in buildings such as wool, nylon, silk, polyurethane and acrylonitrile. If inhaled, Hydrogen cyanide gas inhibits the use of oxygen by the body, which is called histotoxic hypoxia.
Smoke can move faster than a human can run. It has an irritant affect upon the eyes and inhalation causes normal brain functions to close down. Breathing smoke particles will cause a person to feel like they want to go to sleep, rather than escape.