On a bus, you may sometimes haul small-arms ammunition, emergency shipments of drugs, or hospital supplies. The total weight of all such hazardous materials must not be greater than ________________.

Buses may carry small-arms ammunition labeled ORM-D, emergency hospital supplies, and drugs. You can carry small amounts of some other hazardous materials if the shipper cannot send them any other way. Buses must never carry: Division 2.3 poison gas, liquid Class 6 poison, tear gas, irritating material. More than 100 pounds of solid Class 6 poisons. Explosives in the space occupied by people, except small arms ammunition. Labeled radioactive materials in the space occupied by people. More than 500 pounds total of allowed hazardous materials, and no more than 100 pounds of any one class. Riders sometimes board a bus with an unlabeled hazardous material. Do not allow riders to carry on common hazards such as car batteries or gasoline. [Commercial Driver's License Manual]