SMOKE GASES

Carbon dioxide levels increase and oxygen concentrations decrease...

Carbon Monoxide and hydrogen cyanide are the two principal toxic combustion gases. Most cabin furnishings contain carbon and will generate both Carbon Monoxide and carbon dioxide when burned; Carbon Monoxide can also be released from faulty cabin heaters. Burning wool, silk, and many nitrogen-containing synthetics will produce the more toxic hydrogen cyanide gas. Irritant gases, such as hydrogen chloride and acrolein, are generated from burning wiring insulation and some other cabin materials. Generally, carbon dioxide levels increase and oxygen concentrations decrease during fires.

  SMOKE EFFECTS

At high altitude, the effects are greatly enhanced...

Visual smoke can delay escape from a fire, while the irritant gases can induce tears, pain, and disorientation. The visual obscuration is obvious, but the subtle effects of Carbon Monoxide and hydrogen cyanide inhalation, although less readily detected, can cause physical incapacitation and subsequent death. Toxicologically, Carbon Monoxide combines with the hemoglobin in blood and interferes with the oxygen supply to tissues, while hydrogen cyanide inhibits oxygen utilization at the cellular level. Carbon dioxide, a relatively innocuous fire gas, increases the respiration rate causing an increase in the uptake of the other combustion gases.

The decreased oxygen level found in most fire scenarios further enhances the problem of getting enough oxygen to the biological sites to maintain normal function. Continued inhalation of these gases can result in severe hypoxia. At high altitude where oxygen levels are lower, the effects of Carbon Monoxide and hydrogen cyanide are greatly enhanced.

SIGNS AND SYMPTOMS

Not all symptoms will necessarily be experienced...

Carbon Monoxide poisoning produces headache, weakness, nausea, dizziness, confusion, dimness of vision, disturbance of judgment, and unconsciousness followed by coma and death. Although Carbon Monoxide causes deleterious effects on the central nervous system, death usually occurs from cardiotoxicity. Not all symptoms will necessarily be experienced by every individual exposed to this gas. Some have succumbed from inhaling low Carbon Monoxide levels, while others have survived breathing higher concentrations.

Hydrogen cyanide poisoning signs and symptoms are weakness, dizziness, headache, nausea, vomiting, coma, convulsions, and death. Death results from respiratory arrest. Hydrogen cyanide gas acts very rapidly-symptoms and death can both occur quickly.