Statistical Analysis of Fire Department Response Times and Effects on Fire Outcomes in the United States

Understanding the relationship between fire department response times and fire outcomes is critical for understanding the impact of a fire department in a community. This paper outlines a statistical analysis of United States fire department response times to fires in 1-2 family residential dwellings between the years 2002-2017. Using data from the National Fire Incident Reporting System (NFIRS), it is shown that a log-normal distribution provides a reasonable approximation of the empirical distribution of response times. Furthermore, this paper investigates the effect of increasing response times on several different measures of fire severity, including the reported fire spread category, the estimated monetary property and contents losses, and the reported flame damage. It was found that all averaged measures of fire severity increase over the interval of 3-13 min of response time, which is primarily due to the increased likelihood of very severe fire incidents at longer response times. An analysis was conducted to assess the effect of meeting the first unit response time benchmarks outlined in NFPA 1710 on the severity of fire outcomes in a community. It was found that department response times were most strongly correlated with the fraction of fires that do "extreme" damage to at least one story and the fraction of the property value lost. It has been proposed that a power law distribution is appropriate for modeling the distribution the burned areas in urban fires. In order to assess whether this proposition is supported by United States data, a Monte-Carlo methodology has been developed to estimate the burned area indirectly from NFIRS data. Finally, several methods are presented for evaluating data consistency and quality from the NFIRS reports. One of the major findings of this study is the quantification of the effect of response time on various measures of fire loss.