Toxic Yield.
Toxic Yield.
(219 K)
Pitts, W. M.
Technical Basis for Performance Based Fire Regulations.
A Discussion of Capabilities, Needs and Benefits of Fire
Safety Engineering. United Engineering Foundation
Conference. Proceedings. United Engineering
Foundation, Inc. January 7-11, 2001, San Diego, CA,
United Engineering Foundation, Inc., New York, NY, Cox,
G., Editor(s), 76-87 pp, 2001.
Keywords:
regulations; fire safety; safety engineering; toxic
products; experiments; carbon monoxide; fire chemistry;
fire fatalities; fire gases; fire hazard; room fires;
underventillated combustion
Abstract:
It is generally recognized that the vast majority of
deaths associated with accidental enclosure fires are
due to smoke inhalation. Older reviews of autopsy
results suggested that the fraction was on the order of
2/3. In the United States there is evidence that this
number has been growing in recent years and is
approaching 3/4. Autopsy results have also shown that
the vast majority of these fire victims have
carboxyhemoglobin levels in their bloodstreams
sufficient to induce incapacitation or death. This has
led many researchers to conclude that carbon monoxide
(CO) is the dominant toxicant present in fire gases. It
is recognized that the elevated carbon dioxide (CO2)
levels (which result in increased respiration rates) and
depressed oxygen (O2) levels associated with the fire
gases act together to increase the susceptibility of
victims to CO asphyxiation. The importance of CO
toxicity is highlighted by the conclusion that most
victims in the United States are overcome at locations
remote from the room of fire origin. In recognition of
the central role that CO plays in smoke inhalation fire
deaths and the fact that mechanisms for CO formation in
fires were poorly understood, the National Institute of
Standards and Technology initiated an investigation of
CO formation in fires over a decade ago. In the interim,
significant progress has been made on identifying the
formation mechanisms for CO within an enclosure
containing a fire. As will be discussed, additional
investigation is necessary to provide an adequate
understanding of the subsequent reaction and transport
of CO upon exiting the fire enclosure. This paper
focuses on the current understanding of CO formation
mechanisms in real-scale fires with a particular
emphasis on post-flashover generation.
Building and Fire Research Laboratory
National Institute of Standards and Technology
Gaithersburg, MD 20899