What must be established before responders are allowed to enter a hazardous scene?

Before responders are permitted to enter a hazardous scene, it is crucial to establish backup teams and medical monitoring. This ensures that there are both additional personnel available to assist in the event of an emergency and that the health of responders is continuously monitored to detect any signs of exposure or distress. Having a backup team allows for rapid intervention if a responder encounters a situation that exceeds their ability to manage safely or if they need assistance. Medical monitoring serves to protect responders' health, providing immediate care or evacuation if necessary.

While other options such as evacuation protocols, notification of authorities, and public announcement systems may be important in various situations, they do not specifically address the immediate safety and health of the responders entering the hazardous scene. Therefore, establishing support systems through backup teams and medical monitoring is foundational for ensuring the safety of all personnel involved in the operation.