Assessment of pre-warning, pre-travel and travel behavior interactions with smoke and toxic gases during fire incidents

• Published in: Fire safety journal 2023-12, Vol.141, p.103938, Article 103938
• Main Author: Purser, David A.
• Format: Article
• Language: English
• Subjects: carbon monoxide; CO HCN toxicity; data quality; Fire chemistry; Fire investigation; fire safety; Forensic; fuels; Hazard evaluation; Human behavior; probability; smoke; toxicity; travel
• ISSN: 0379-7112
• DOI: 10.1016/j.firesaf.2023.103938

Evaluation of potential fire scenarios and escape outcomes involves data and calculations for many different parameters and their interactions, with uncertainties regarding application to real systems. Assessment of fire development, occupant behaviors and effects of toxic smoke exposure during actual incidents can provide a reality check on engineering methods, data quality, assumptions and limitations. Because incidents encompass the performance of entire occupied built systems, they enable witness accounts, survival, medical and pathology outcomes and evidence of fire development and toxic smoke spread to be combined with fire, evacuation and toxicity modelling calculations. Since outcomes are known, they constrain the predictions derived, revealing previously unidentified parameters and enabling validation of current methodology. Examples from incidents highlight the following findings. • Pre-warning delays – neglected parameter, high consequence. • Effects of fire cues and warnings on occupant behavior and pre-travel times, and stair descent speeds in relation to visibility – generally validate current methods. • Probability of evacuation through irritant smoke– high consequence, needs more consideration. • Times to incapacitation from asphyxiant gases as a function of fuel composition and smoke density – useful assessment method. • Using smoke and carbon monoxide exposure toxicology to estimate fire development and exposure history - Useful method for fire scenario validation, confirms FED method validity. •Fire incident investigation by integration of fire dynamics, behavior and toxicity evidence.•Evacuation pre-warning delays had high consequences for survivability.•Pre-travel times and behaviors during incidents consistent with current methodology.•Low probability of entering irritant smoke had high consequence for outcomes.•Time to incapacitation can be derived from smoke:CO ratios for scenario validation.