FIRE INVESTIGATION CHANGE AND EVOLUTION, PART 1: AN OVERVIEW
This article is the first of a series describing the ongoing changes in the fire investigation field, aimed at ululating and educating fire investigators as well as other personnel involved in fire investigation.
Fire investigation is changing at a rapid pace. These changes are the result of a number of developments in the understanding of fire behavior as well as direct efforts to transfer new knowledge into fire investigation technology. Years of basic research in fire behavior by the National Institute of Standards and Technology’s (NIST’s) Building and Fire Research Laboratory (BFRL, formerly the National Bureau of Standards, Center for Fire Research), Factory Mutual Research Corporation, and numerous universities and private companies have led to greater understanding of how fires start and grow.
For instance, the phenomenon of flashover and its importance to a developing fire only now are being understood and have just started to make their way to fire investigators. Another milestone of progress for fire investigation was reached when the National Fire Protection Association (NFPA) published the first edition of NFPA 921, Guide for Fire and Explosion Investigation, in February 1992. This manual was the first of its kind in the field of fire investigation written by a committee of people who each contributed special knowledge of and experience in fire investigation.
Unlike many previously published materials in the field, its facts were carefully checked to ensure they agreed with the laws of science, and it will undergo periodic updates. The committee has reviewed NFPA 921 numerous times, and the Guide was open to comment by the general public twice before being adopted.
Even today, fire investigation seminars are being conducted that are seriously flawed in their science, have not been updated to reflect the latest technology and research, and make no mention of NFPA 921. These seminars serve only to reinforce the “old wives’ tales” and fire investigation myths that hurt investigators’ credibility. It is hoped that this and future articles bring these deficiencies to the attention of the fire investigation community as well as to those who employ them in the interest of advancing the science.
FIRE RESEARCH
Modern fire research really began during World War II. The vulnerability to and resulting damage from incendiary attacks in Europe and Japan led many countries to develop methods for evaluating the ability of structures to withstand fire. This research continued and expanded in the postwar years to become what it is today. One problem, however, has continued to characterize the fields of fire research and fire protection: Often it takes a major fire with multiple casualties before codemaking groups, legislators, and the fire research community act on a particular fire problem. (Such was the case with the problems of combustible ceiling finish, inadequate exits, and open stairs.) And even after the magnitude of certain problems are recognized, fires still occur where the lessons learned are the same as they were 50 years ago. Examples are the fires at the Happy I-and Social Club in New York City and the DuPont Plaza Hotel in Puerto Rico.
Early on, it was recognized that the size and complexity of buildings and their contents made full-scale tests to evaluate fire behavior in them expenive and difficult. Today, environmental regulations prevent or restrict much fire research. For these reasons, fire researchers have sought to understand the fundamental rules of fire behavior and then apply that understanding to predict fire behavior. One of the results of this approach is fire modeling. With a fire model, it is possible to predict how a particular fire will affect a room or rooms within a building under specific conditions. Fire models typically run on a computer, which uses the data collected from fire tests and the results of fire analysis to predict outcomes. Some models specialize in predicting the toxicity of smoke or determining the likelihood of occupant escape from a building. Fire models have become a new and powerful tool for the fire investigator as well. Now it is possible to look at a fire scene after the fact and, with the help of a model, gain insight into aspects of the fire, such as the following:
- How long did it take for the fire to reach flashover?
- What was the carbon monoxide concentration in the room next to the room of origin?
- When should the first smoke detector and automatic sprinkler have activated?
These and numerous other examples show what these new tools can do for fire investigation, things that, until recently, were impossible to determine or could only be estimated unless a reliable eyewitness was available.
Fire research also has provided fire investigators with scientifically sound explanations for phenomena fire investigators have observed for years at fire scenes. Conversely, it has opened to question things considered to be undisputable evidence for a particular fire effect. An example is burn patterns on the floor, which long have been held as evidence that an ignitable liquid had been burned on the floor. However, research into the flashover phenomenon and other fire effects has shown that floor burn patterns may have other causes.
For many reasons, integrating new technolog)’ and fire research data into the fire service and fire investigation field has been slow. Many fire investigators have their roots in the fire service, where the inertia of tradition sometimes has been difficult to overcome. Research findings often are published in language incomprehensible to anyone without a Ph.D-making them useless for most fire investigators; and, until recently, this research was not geared specifically to fire investigation problems.
Training for fire investigators typically has involved classes or seminars produced by local, state, or federal agencies; insurance companies; and investigator associations. The system has been successful, educating many competent fire investigators; but when changes started to occur and new technology became available, some trainers did not update their programs.
For example, one recent seminar included a presentation on the uses of a computer in fire investigation. The presentation centered on how fire investigators could use word processors to keep notes. No mention was made of fire models, computer-aided drawing (CAD), or other uses of real value to fire investigators. Curriculum changes have been met with resistance for many reasons, most of which probably fit into the category of “because we’ve always done it this way.” For this and other reasons, the NFPA formed the Technical Committee on Fire Investigation in 1984, which was charged with developing a manual on how fire investigation should really be done.
NFPA FIRE INVESTIGATION COMMITTEE
Once the NFPA decided to form a fire investigation technical committee, it solicited membership applications from its members and the general public. NFPA rules mandate that its committees be “balanced,” that is, they must represent all the groups to which their documents would apply. Members of the fire investigation committee represent the fire service, insurance companies, the federal government, state fire marshal offices, researchers, the legal profession, private investigators, and special experts. This group was charged with writing a new manual and also became responsible for NFPA 907M, Determination of Electrical Fire Causes (1988 edition), which had been written by an electrical fire investigation committee that first met in 1977.
In November 1991, at the NFPA Fall Meeting in Montreal, Canada, members voted to accept the first edition of NFPA 921, Guide for Fire and Explosion Investigation. It was published in the spring of 1992. Since that time, the members of the Fire Investigation Committee have been preparing new material for inclusion in the second edition, due out in the spring of 1995.
The first edition of NFPA 921 has 14 chapters: Administration, Basic Methodology, Basic Fire Science, Fire Patterns, Legal Considerations, Planning the Investigation, Sources of Information, Recording the Scene, Physical Evidence Examination and Testing, Safety, Origin Determination, Cause Determination, Explosions, and Referenced Publications.
NFPA 921 now is being used in whole or part as a textbook by such agencies as the Connecticut State Fire Marshals Office, the National Association of Fire Investigators, and the National Fire Academy. It has been and will continue to be used in the courtroom as an authoritative reference on fire and explosion investigation. The next edition of NFPA 921 will include chapters on incendiary fires, automobile fires, major fires, appliances, and investigating electrical fires. It is anticipated that the current NFPA guide for electrical fires, NFPA 907M, will be absorbed into NFPA 921 as a new chapter with much updating.
NFPA 921 was written for beginning and experienced fire investigators. This broad audience made writing the manual difficult, since it had to be technical enough to present the science accurately but not so technical that a beginner could not use it as a textbook. NFPA 921 presents the science behind the “tools” of fire investigation, such as fire patterns, so that the investigator understands their origin and meaning. It was hoped that this would dispel the fire investigation myths still prevalent and prevent newmyths from forming. The survival of myths threatens the credibility of individuals and the fire investigation community at large.
FIRE INVESTIGATION MYTHS
It was the persistence of repeatedly repudiated myths that in part prompted the formation of the NFPA Fire Investigation Committee. These myths originated in the days before fire models, gas chromatograms, and fire research. They were based on rules of thumb and general observations made at fire scenes. In their day, they had some merit, but they were not scientifically based and did not change to reflect changes in the science of fire investigation. Like the flatearth concept, many of the myths appear rational under narrow scrutiny-they seem valid as long as you do not look too far or expect the myth to conform to basic physical laws. These myths, however, have retained credibility because of the number of fire investigators and fire experts using them.
Certain elements of fire investigator training have been based on these myths and other unscientific principles. For example, many investigators have been taught that there are four modes of heat transfer: convection, conduction, radiation, and direct flame contact. The engineering and scientific communities recognize only convection, conduction, and radiation; direct flame contact is a combination of convection and radiation heat transfer. Other popular fire investigation myths include those regarding V-patterns, low burning, depth of char, origin based on greatest fire damage, floor burn patterns, spalling of concrete, fire seeking oxygen, and arson indicated by “fast” fires. Each of these myths and others will be discussed in detail in future articles.
FIRE INVESTIGATION FUNDAMENTALS
Before exploring these myths, it is important to review and reinforce the fundamentals of fire investigation, which should be second nature to all fire investigators. Objective and valid investigations into the origin and cause of fires depend on knowledge of these fundamentals. An investigation must start as an objective collection of data and facts from which theories will be formulated. This requires the investigator to have an open mind and not be prejudiced toward any particular fire cause. Information is collected by visiting and documenting the fire scene. No conclusions are made at this point, but data, in the form of diagrams, photographs, interviews, and other observations, are collected. Data also may be collected remote from the fire scene. As the quantity of data increases, the investigator analyzes it and begins to formulate theories and a hypothesis with regard to the fire’s origin and cause. Before this hypothesis can be put forth as a conclusion, it must be tested by considering and eliminating all other reasonable origins and causes.
If the hypothesis cannot withstand this test, it must be discarded or modified and retested. If no hypothesis can withstand this type of scrutiny, then the cause must be listed as “unknown.” Listing a fire as “suspicious” based on inconclusive data is not valid and contributes nothing to the field of investigation. This term should not be used in reports or incident forms unless conclusive evidence of an incendiary fire exists, in which case the fire should be listed as incendiary or arson. The collection, preservation, and presentation of investigation data without conclusions are valuable because at a later date additional data may be developed or the original data may become useful to someone with specialized expertise.
Future articles will discuss flashover as it relates to fire investigation, fire models, and fire investigation myths.
