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Although these devices are no substitute for
carefully planned fire prevention measures, they are invaluable to providing
an early warning when fire strikes. Smoke is the cause of the majority of
fire-related deaths. Hot flames are low on the list of killers during a
fire. A smoldering fire may go undetected for hours, especially while people
are asleep. In addition to deadly carbon monoxide, smoke carries poisons
such as hydrogen cyanide and irritants such as formaldehyde and acetic acid.
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Added to this lethal potion
are other toxic substances that come from the burning of synthetic materials
commonly found in the home, especially those emitted from plastics and
foams. Oxides of nitrogen, sulphur dioxide and ammonia are just a few
examples. These agents can have a lethal effect before a sleeper is even
disturbed; especially when one considers that the fire itself consumes
life-sustaining oxygen.
Normally, air is made-up of about 21 percent oxygen. When it falls below the
17 percent level, thinking and coordination become difficult. Below 16
percent, a person's behaviour turns irrational, hindering escape efforts.
Breathing becomes impossible when oxygen levels fall below 6 percent.
Temperatures above 370°C (700°F) are common in a "hot" fire. At such high
temperatures, unconsciousness and death can occur within minutes. Bedrooms
located in the upper floors of residences are frequently subjected to these
conditions in the advanced stages of a fire. |