Which term describes the act of using a sign to indicate that hazardous materials are inside a vehicle or container?

The term that describes the act of using a sign to indicate that hazardous materials are inside a vehicle or container is placarding. Placards are specific signs displayed on the outer surface of a vehicle or container that communicate the presence of hazardous materials. They serve to inform emergency responders and others that dangerous substances are being transported, allowing for appropriate safety measures to be taken.

In the context of transportation and logistics, placarding is a vital practice that ensures safety and compliance with regulations relating to hazardous materials. It helps prevent accidents and improves situational awareness, particularly in emergencies. While labeling involves marking individual containers for proper identification and handling, and signage could denote various types of information, placarding is the specific term used for the display of signs indicating the transportation of hazardous goods.