ISO 17723-1:2019 establishes minimum design and performance requirements for personal protective ensembles to be worn during hazardous materials responses involving chemical gas, vapour, liquid, and particulate hazards. This document provides optional criteria to address protection during terrorism involving chemical and biological agents. This document provides optional criteria to address the ability of ensembles to retain their integrity during escape in the event of chemical flash fire. This document does not establish minimum criteria for protection against radiological hazards, flammable, or explosive atmospheres. This document does not pertain to clothing providing the high level of heat and flame protection that is required for fighting fires. This document does not address respiratory protection.