Chapter 6 – Firefighter Survivability and Structural Stability
A 30-year review of NFPA annual firefighter fatality reports by the Fire Analysis and Research Division identified a concerning trend (Fahy, 2007, p. 49);
The one area that had shown a marked increase during the period is the rate of deaths due to traumatic injuries while operating inside structures. In the late 1970s, traumatic deaths inside structure occurred at a rate of 1.8 deaths per 100,000 structure fires and by the late 1990s had risen to approximately 3.0 deaths per 100,000 structure fires. Since that time, the rate has fallen and now stand at 1.9 deaths per 100,000 structure fires, a rate only slightly lower than that observed in the early 1980s. Almost all of the non-cardiac fatalities inside structure fire were the result of smoke inhalation (62.1 percent), burns (19.1 percent) and crushing or internal trauma (16.5 percent).
Although firefighter deaths per 100,000 structure fires have decreased since the late 1990s, there are newer concerns the fire officer must be aware of. The hazards firefighters are exposed range from those like building construction, building contents and fire dynamics.
The modern fire environment has seen the introduction of a number of new elements that are changing the way fires grow and spread. Buildings structural members are made with low surface-to-mass ratios which allow them to more rapidly break down and become less stable, thus failing sooner. Foam insulation that when heated, rapidly releases toxic gasses. Open floor plans allow for air to move more easily through the structure creating energy with higher efficiency.
Many of the contents in homes today are made from man-made synthetic materials. Today’s smoke contains some of the most dangerous and fatal chemicals known, including; hydrogen cyanide, polyvinyl chloride, formaldehyde, hydrogen chloride and carbon monoxide. Not only is modern fire smoke significantly more toxic than the smoke of yesterday but there is more of it. Synthetic building contents have a smoke production level that may be as much as 500 times that of a similar fire burning wood and cotton contents.
The information coming from NIST and ULFSRI have provided context into the ways the fire dynamics are changing the fire environment. Implementing fire dynamic principles on the fire ground is a tool probationary and veteran firefighters must learn and develop. The ability to identify flow paths is important to determine where a fire is, and where it may go in the future. The skill of interpreting smoke and understanding its relationship to pressure will provide clues to the fire’s level of involvement, location and possibility for growth.
Understanding the variety of problems in today’s modern fire environment will hopefully equip the Fire Officer with the tools necessary to identify and mitigate modern hazards.
Structural failure can occur at any time. Fire intensity, burn time, content loads and construction methods and materials all affect structural stability. As fuel packages and heat release rates have increased, changes to building design and construction have created new challenges for firefighters. Increasingly, buildings are being constructed from lightweight and engineered materials and components decreasing their ability to withstand the effects of fire. As a result, we are seeing buildings fail faster than ever before.
Always consider structural stability when sizing up the fire scene.