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RISK MITIGATION
It is apparent from the above discussion that the health risks associated with carbon fibers are not clearly understood.
There is a lack of scientific studies which conclusively link exposure to airborne carbon fibers and combusted
resin residues to severe health impact on personnel, or that risks of inhalation are similar to other known pathogenic
and carcinogenic fibers such as asbestos. However, it is prudent for safety personnel engaged in various stages of
an aircraft mishap response to take precautionary measures. The US Air Force Advanced Composites Program [34]
has developed guidelines establishing minimum safety and health protection requirements for firefighters, investigators,
and cleanup crews in accidents involving aircraft with advanced composite materials. These guidelines were
established to prevent acute inhalation and dermal exposure to various pollutants including respirable fibers. All
personnel working in close proximity to a crash-site are required to wear self-contained breathing apparatus, chemical
protective clothing, leather gloves, and neoprene coveralls to minimize exposure to all airborne species. Once
the fire is extinguished, the scattered debris is sprayed with a fixing agent such as polyacrylic acid or liquid floor was
mixed with water to agglomerate the loose fibers and frayed edges of composite parts. Personnel working in close
proximity to crash location and engaged in recovery and removal of fragmented composite parts should wear NIOSH
approved half-mask respirators with cartridges for organic vapors and fumes, and carbon fibers and dusts. All
personnel also wear leather gloves and impermeable Tyvek or equivalent coveralls.
CONCLUSIONS
Aircraft fires involving advanced composite materials present hazardous conditions during the fire fighting, rescue,
and investigation and recovery operations in a postcrash situation. Release of a mixture of gaseous, particulate, and
other combustion products of unknown composition poses unique protection problems. A small fraction of carbon
fibers released from burning composites are of respirable size and contaminated with a diverse range of chemicals
including polycyclic aromatic hydrocarbons, nitrogenous aromatics, and phenolics. There have been both anecdotal
and a few cited reports [1-4] indicating that firefighters and rescue people responding to such aircraft fires have
suffered adverse health effects ranging from skin irritation, puncture, and sensitization to severe respiratory problems
from inhalation of fiber particulates. Data available from research on exposures during manufacturing of carbon
fibers and during machining, milling, and sawing of composite materials, indicate that no adverse health effects
occur from inhalation of carbon fibers. However, the previous studies were focused on the short-term, chronic
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workplace exposure to airborne carbon fibers and composite dusts, not on the long-term health effects from a single
high exposure to airborne fibers which is expected in aircraft crash and rescue situations. The long-term health
outcomes due to inhalation of micron-sized carbon fibers contaminated with an array of organic chemicals generated
in aircraft fires are largely unknown. No epidemiological data are available on the extent of personnel exposure
to such combustion products from burning composites. Similarly, no animal studies have been conducted with the
required post-exposure duration to assess the toxicology of the carbon fibers generated in a fire scenario. Synergistic
interactions between the solid, vapor, and gaseous combustion products remain to be identified. Detailed toxicological
studies are needed to assess the toxicity implications of combustion products from advanced composites.
Efforts to fill these gaps in our knowledge of these recently recognized hazards, both in the United States and
England, are still at a preliminary stage. Until adequate assessments are made, use of personal protective equipment
(PPE) can mitigate the dangers encountered by crash rescue personnel. In the absence of complete PPE
ensemble, particle filtration masks may provide some measure of protection. Guidelines, developed by the USAF for
adequate protection of the various response personnel during handling and disposal of composite wreckage, should
also be made available to civilian and airport fire fighting and rescue personnel that are often the first to respond to
a postcrash fire. It is equally important to document the on-site exposure among the personnel responding to the
crash site to establish specific protective-gear requirements and adequate requirements for fire fighting effectiveness.
REFERENCES
1. Bickers, C. 1991. “Danger: Toxic Aircraft,” in Jane’s Defense Weekly, p. 711.
　
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