This document specifies minimum design and performance requirements for personal protective equipment (PPE) to be used by firefighters whilst engaged in fighting fires occurring in structures, primarily but not solely to protect against exposure to flame and high thermal loads. The scope of this document does not include PPE for use in high risk fire exposures where, for example, protective clothing with reflective surface according to ISO 15538 might be more appropriate, where exposure to lower levels of heat or flame may be encountered by firefighters engaged in support activities where PPE according to ISO 11613 might be more appropriate, or for use in long term firefighting operations in high ambient temperature (for example, bush, wildland, or forest firefighting) where PPE according to ISO 16073 might be more appropriate. Similarly, this document does not include PPE to protect against chemical and biological hazards, other than against short term and accidental exposure while engaged in firefighting and associated activities when fighting fires occurring in structures. This part of ISO 11999 supports the structure identified in ISO 11999-1 for a harmonised approach across all parts of this series by setting single minimum design and performance requirements for PPE, including optional requirements where identified, and for product markings and manufacturer’s instructions. Selection of an appropriate system of protective clothing is dependent upon an effective risk assessment which identifies the hazards to be faced, evaluates the likelihood of those hazards, and provides the means to reduce or eliminate these hazards (see ISO 21808).