2005 Commercial Driver’s License Manual Allow riders to exit by any window or door in an emergency. Protect riders from injury if carry-ons fall or shift. 4.2.1 – Hazardous Materials Watch for cargo or baggage containing hazardous materials. Most hazardous materials cannot be carried on a bus. The Federal Hazardous Materials Table shows which materials are hazardous. They pose a risk to health, safety, and property during transportation. The rules require shippers to mark containers of hazardous material with the material's name, identification number, and hazard label. There are nine different four-inch, diamond-shaped hazard labels. See Figure 4.1. Watch for the diamond- shaped labels. Do not transport any hazardous material unless you are sure the rules allow it.