Presented at International Symposium of Fire Investigation, 2014
During the investigation of most fires, including fatal fires, the investigators focus almost all of their attention to the questions of cause and origin. This has been the traditional purpose of fire investigation. Because of this, the type of smoke detector involved, i.e. ionization or photoelectric, is seldom a factor that is considered important. In fact, in some cases little effort is made to determine if a smoke detector was even present. Complicating the investigation of this aspect of the fire is the fact that quite often the ceilings have been pulled down, along with the remains of the detector in an effort to extinguish the fire. The smoke detector, at least what is left of it, is buried in debris and difficult to recognize. In addition, the different factors that can affect a smoke detector’s ability to detect a fire in time to alert the occupants are not well understood. As a consequence, investigators are not aware of any reason to investigate the operation of the smoke detector.
In this paper we show why investigating aspects of smoke detector performance may be important, if not to address the cause and origin of the fire, at least to understand better the cause of injuries and fatalities. In doing this we endeavor to answer some questions that some investigators have had as to why some detectors may not have gone off in time to alert the occupants. In many cases investigators improperly assume that if the occupant did not escape, then this means that the smoke alarm did not operate. We also discuss the national statistic regarding smoke alarms and how the failure to collect relevant information may be leading to incomplete and misleading data analysis. Since Massachusetts started to collect this information and apply lessons learned to public education and code improvements, the fire death rate per capita has dropped much faster in Massachusetts, than in the US as a whole. While there may be many reasons for this, we are confident that better collection of data involving smoke alarms is a major factor.