b. Ammonia is formed when acrylic plastic or phenolic and melamine resins are burned. Exposure to 0.25 to 0.65%
ammonia gas for one-half hour can cause death.
c. Hydrogen cyanide is highly toxic and is formed when urethane, nylon, or melamine are burned. Breathing a
concentration of 0.3% is fatal. It can also be absorbed through the skin, causing the same results. The characteristic
bitter almond odor sometimes warns of hydrogen cyanide presence.
d. Hydrogen chloride is a fire gas produced during the combustion of chlorine-based plastics such as PVC electrical
cable insulation. It is absorbed in smoke and, when breathed, desorbs as hydrochloric acid deep in the lungs. It can
cause death due to lung edema.
e. Phosgene gas is highly toxic and is produced when polyvinylchloride, refrigerant, or other chlorinated compounds
are involved in a fire.
6-9. FLAME. The burning of materials in the presence of a normal oxygen-rich atmosphere is generally accompanied
by flame. For this reason, flame is considered a distinct product of combustion. Burns can be caused by direct contact
with flames or heat radiated from flames. It is rarely separated from the burning materials by an appreciable distance. In
certain types of smoldering fires without evidence of a flame, heat and smoke and gas can develop. Air currents can
carry these elements far in advance of the fire.
6-10. HEAT. Heat is the combustion product mostly responsible for the spread of fire. It poses dangers that range from
minor injury to death. Exposure to heated air can cause heat exhaustion, dehydration, blockage of the respiratory tract,
and burns. Exposure to temperatures above 1300 F without respiratory protection is extremely hazardous. One or two
breaths of moisture-saturated air at such temperatures can cause serious respiratory system damage.
6-11. SMOKE. Smoke is matter consisting of very fine solid particles and condensed vapor. These combustion
products are usually evolved from the combustible with sufficient velocity to carry with them droplets of flammable tars
which appear as smoke. Smoke provides the warning of fire and simultaneously contributes to the fear of those in the
smoke by the nature of its blinding and irritating effects. Smoke causes eyes to water, which impairs vision and also
causes irritation to the respiratory tract and uncontrollable coughing.
6-12. ASH. Ash is the residue of burned materials. It can contain any chemical that results from the burning of basic
fuel such as hydrogen chloride and carbon fibers. It may also contain residue from fire extinguishing agents (i.e., dry