What does ISR stand for in fire investigations?

In fire investigations, ISR stands for Ignitable Substance Residues. This term refers to the traces of materials that can ignite and contribute to the start and spread of a fire. Identifying these residues is crucial during an investigation, as it provides evidence of the types of substances that were present at the scene before the fire occurred. The presence of ignitable substance residues can help investigators determine whether the fire was accidental, intentional, or a result of negligence.

Other options, while they may contain relevant terms related to safety and materials, do not specifically pertain to the context of fire investigation. For example, Internal Safety Regulations could pertain to safety procedures within an organization, but they do not address the actual physical evidence examined in fire scenes. Irritant Substance Residues might seem related due to a focus on substances, but it is not a recognized term in the context of fire investigation. Immediate Safety Response focuses on actions taken to ensure safety during and after emergencies, rather than the forensic analysis of materials involved in the fire.