You can carry small amounts of some other hazardous materials if the shipper cannot send them any other way. 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.
They may not know it is unsafe. Do not allow riders to carry on common hazards such as car batteries or gasoline. No rider may stand forward of the rear of the driver's seat. Buses designed to allow standing must have a 2-inch line on the floor or some other means of showing riders where they cannot stand. This is called the standee line.