What must emergency services be notified of during a HazMat incident?

Emergency services must be notified of the specific type of hazardous materials involved during a HazMat incident because this information is crucial for their safety and response effectiveness. Understanding the types of materials allows responders to assess the risks associated with the incident, including potential health hazards, explosive risks, or environmental impacts. Each hazardous material may require different containment, cleanup, or evacuation procedures, and knowing what responders are dealing with helps them utilize the appropriate protective equipment and strategies to manage the situation effectively.

The other options, while they may have some relevance in certain contexts, do not provide essential information that directly influences the immediate response to a hazardous materials incident. For example, knowing the nearest hospital may be useful for patient transport, but it does not aid in managing the hazards on-site. Awareness of witnesses could be relevant for gathering information post-incident, but it does not contribute to the operational response. Similarly, the time of day does not impact the handling of hazardous materials during the incident itself; the nature of the materials is far more critical for ensuring the safety of responders and the public.