Where can information corresponding to a four-digit UN or DOT identification number be found?

The Emergency Response Guide is the correct source for information corresponding to a four-digit UN or DOT identification number. This guide is specifically designed to assist first responders in emergency situations involving hazardous materials. The UN (United Nations) and DOT (Department of Transportation) identification numbers are crucial for identifying substances quickly and safely during incidents, as they provide critical information about the materials involved.

The Emergency Response Guide contains detailed descriptions of hazardous materials, their potential hazards, and appropriate response measures. It enables responders to effectively manage situations involving these substances, ensuring both safety and compliance with regulatory standards.

While other options might contain useful information during emergencies, they do not specifically offer the comprehensive chemical information tied to the four-digit identification numbers like the Emergency Response Guide does. For instance, the Post Order Book is typically focused on internal procedures rather than specific hazardous materials, and local police and firefighters may have access to general emergency response protocols but may not hold the specialized information concerning hazardous substances that the Emergency Response Guide provides.