What is the first step in assessing the scene during an emergency response?

Ensuring scene safety and BSI (Body Substance Isolation) is the essential first step in assessing the scene during an emergency response because it establishes a safe environment for both the responder and the patient. If the scene is unsafe, entering it could lead to further injuries not only for the bystanders but also for the emergency personnel. Body Substance Isolation involves using precautions to prevent exposure to potentially infectious materials, thus protecting the responder from possible diseases.

Prioritizing safety allows responders to perform their duties effectively without risking their own lives or the lives of others. This foundational step sets the stage for subsequent assessments and interventions, including evaluating the number of patients, determining transport needs, and understanding the mechanism of injury or nature of illness. Addressing these aspects comes only after ensuring that the scene is secure for everyone involved.