Most of these hazardous materials are required to be shipped in containers that meet strict specifications established by the U.S. Department of Transportation (DOT). There are marking requirements that provide an identification of the type of hazard that can be posed by the particular product.
A DOT label is found on individual packages, drums, or other small containers and is in the shape of a 4-inch diamond. A DOT placard is also diamond-shaped, but is larger and found on the outside of the transport vehicle. Placards are used only if there are 1,000 pounds or more of various materials on board.
Diamond-shaped symbols are used in accordance with the National Fire Protection Association (NFPA) for indicating the various hazards of the material in a fixed location such as a storage warehouse.
Encountering a Hazardous Material Accident
Should you come upon an accident involving a container or truck marked with a label, or placard, do not approach. Do not come in contact with any released materials. Remember, hazardous materials may occur in liquid, solid, or gaseous state. Do not smoke or allow any combustion source in the area.
Advise bystanders that the material may be very dangerous and ask them to leave the area immediately. If the material is on fire, or several substances are mixing together, there is a risk of explosion or other violent reaction. Instruct everyone to evacuate from the area to a distance of at least 1 mile.
Report the incident to local authorities immediately. Communicating the following information will greatly speed up the response:
The exact location of the incident
Type of vehicle (container) involved
If there is a fire
The color of the placard or label and any numbers or names printed on them