ISO 13571:2012 is intended to address the consequences of human exposure to the life-threatening components of fire. The time-dependent concentrations of fire effluents and the thermal environment of a fire are determined by the rate of fire growth, the yields of the various fire gases produced from the involved fuels, the decay characteristics of those fire gases and the ventilation pattern. Once these are determined, the methodology presented in ISO 13571:2012 can be used for the estimation of the time at which individuals can be expected to experience compromised tenability.
With care, this guidance can also be applied to estimation of the time limit for rescuing people who are immobile due to injury, medical condition, etc.
ISO 13571:2012 establishes procedures to evaluate the life-threatening components of fire hazard analysis in terms of the status of exposed human subjects at discrete time intervals. It makes possible the estimation of the time at which occupants can experience compromised tenability. It enables estimation of a compromised tenability endpoint for each of the fire effluent components, with the most important endpoint being the earliest to occur.
Although the concept of compromised tenability is consistent with the definition of incapacitation (see ISO 13943), the latter term is not used in ISO 13571:2012 due to its potentially broad interpretation to include many effects, including collapse and unconsciousness, that are not addressed. ISO 13571:2012 focuses specifically on compromised tenability as influenced by both physiological and behavioural responses resulting from exposure to a fire's life-threatening components.
The life-threatening components addressed include fire-effluent toxicity, heat, and visual obscuration due to smoke. In cases where the effluent composition is available, the toxic gas model is to be used for assessment of fire-effluent toxicity. For those cases where the effluent composition is unknown, an additional mass-loss model using generic toxic potency values is provided.