According to ERG Step One, how is the Guide Number determined?

The Guide Number is determined by the four-digit ID number found in the yellow section of the Emergency Response Guidebook (ERG). This number serves as a crucial identifier that allows responders to quickly locate the appropriate guide for the specific substance involved in an incident. Once the ID number is established, it directs responders to the correct hazard category and related safety information necessary for managing the situation effectively.

The four-digit ID number is systematically organized in the ERG, making it easier for users to access vital information about the hazardous material—its properties, potential hazards, mitigation strategies, and emergency response actions. This structured approach ensures that first responders can act swiftly and with the correct resources, reducing risks associated with hazardous materials.

While the other options involve factors that can relate to hazardous materials, they do not directly determine the Guide Number. The volume of the material might influence how much is present at an incident, the color of the placard indicates the type of hazard, and the weight may be relevant for transport and storage considerations, but none of these aspects influence the Guide Number as defined by the ERG.