Change for the Better? – Part 3
Written by John on October 23rd, 2009
THE CHANGING FIREGROUND ENVIRONMENT
Now, let’s turn our attention to 2009. Today, attack personnel are exposed to two significant considerations (and hazards) that attack personnel of the pre-1960 era never encountered.
First, the increased use of synthetic materials that began to increase during the 1970′s and 1980′s are now common as applied to carpets, furniture, wall coverings, plants, electronic appliances, and the list goes on. When these products burn, they produce smoke and fire gases that are more susceptible to flashover-type conditions. Hollywood popularized the term, backdraft, with its award-winning movie, and most firefighters can easily overview the potential indicators for a backdraft. However, ask a modern firefighter to overview the common indicators for a flashover!? Interestingly, if a class of 100 students from the fire service with various backgrounds and seniority are asked to raise their hands if they have ever seen a backdraft, 2-5 students will normally raise their hands! However, when asked about a flashover, approximately 50-70% will raise their hands. So, why is flashover a common modern problem and backdrafts are not, particularly when new structures are tighter than they have ever been and should enhance the possibility of a backdraft? The answer is easily explained when you consider the changing content and use of modern synthetic materials. The lower ignition temperatures of plastics and their resultant smoke and fire gases can easily flashover before a typical fire that is confined to one room (which is 60% of our structure fires) can develop a pressurized, oxygen deficient, confined environment necessary to support a backdraft. Each year the United States averages 100 deaths in the fire service. Of that number, approximately 14-16 normally occur as a result of grass-brush-type incidents. A noteworthy percentage of the remaining 84-86 deaths occur from flashover-type conditions, and the percentage is slowly increasing.
Second, at a time when fire environments are enhancing the conditions for flashover, the modern firefighter is totally encapsulated in protective equipment. This has allowed firefighters to advance to the seat of a fire in a timely manner while minimizing the ability of personnel to monitor and evaluate the fireground environment. If a typical modern firefighter is asked what is used as an indicator, you normally get a blank stare, or, when the front portion of a helmet melts down in front of the face piece, it is time to exit the structure. A common result of these factors is the ability of firefighters to use their protective equipment as an offensive tool, instead of a defensive tool, which allows attack personnel to quickly advance into an environment that can readily flashover! As a prime example, a recent FETN video tape featured a flashover in Biloxi, Mississippi, that resulted in the deaths of two firefighters. A single-story, single-family dwelling was encountered with a working fire in the attic. Well into the incident, the fire had been knocked down but was not fully extinguished, creating a false sense of security. Two firefighters with full protective equipment re-enter the structure for the third time. This was facilitated by the fact the remaining fire was in the attic only, and there was no smoke on the first floor, only radiated heat from the growing attic fire. Shortly after the two firefighters re-enter the structure, the entire structure suffers a flashover, killing the two firefighters.
It is imperative that personnel engaged in suppression operations be aware of, and constantly monitor their fireground environment as follows:
- When entering a structure, make a mental note of conditions. This gives you a baseline to evaluate an environment that will be degrading or improving as you advance into the structure.
- Do you have smoke with no heat, or smoke and heat? An absence of heat would indicate a reduced chance of a problem (food on the stove, etc), while smoke with heat increases the chances for a problem (structure fire, etc).
- Do you have acceptable visibility? Acceptable visibility is defined as being capable of exiting the structure in an acceptable period of time. If you are going to push the envelope at an incident, at the minimum, be able to exit the structure in a timely manner.
- Are conditions improving or not improving? If conditions are not improving, this is an indicator there is a lack of effective fire suppression and/or ventilation operations, and you should begin to evaluate your length of commitment.
In our next article, we will conclude this series with part 4.
