The term "hazardous materials" (HAZMAT) refers to any substances or materials which, if released in
an uncontrolled manner (eg, spilled), can be harmful to people, animals, crops, water systems, or
other elements of the environment. The list is long and includes explosives, gases, flammable and
combustible liquids, flammable solids or substances, oxidizing substances, poisonous and infectious
substances, radioactive materials, and corrosives.

One of the major problems is to determine what chemicals are where and in what quantities. Various
organizations in the US have established or defined classes or lists of hazardous materials for
regulatory purposes or for the purpose of providing rapid indication of the hazards associated with
individual substances. As the primary regulatory agency concerned with the safe transportation of
such materials in interstate commerce, the US Department of Transportation (DOT) has established
definitions of various classes of hazardous materials, established placarding and marking
requirements for containers and packages, and adopted an international cargo commodity numbering
system.

The DOT requires that all freight containers, trucks and rail cars transporting these materials display
placards identifying the hazard class or classes of the materials they are carrying. The placards are
diamond-shaped, 10-inches on a side, color-coded and show an icon or graphic symbol depicting the
hazard class. They are displayed on the ends and sides of transport vehicles. A four-digit identification
number may be displayed on the placard or on an adjacent rectangular orange panel. If you have
spent time on the roads you have undoubtedly seen these placards or panels displayed on trucks and
railroad tank cars. You may recognize some of the more common ones, such as 1993, which covers a
multitude of chemicals including road tar, cosmetics, diesel fuel and home heating oil. Or you may
have seen tankers placarded 1203 filling the underground tanks at the local gasoline station.

In addition to the placards, warning labels must be displayed on most packages containing hazardous
materials. The labels are smaller versions of the placards (4-inches on a side). In some cases, more
than one label must be displayed, in which case the labels must be placed next to each other. In
addition to labels for each of the DOT hazard classes other labels with specific warning messages
may be required. Individual containers also have to be accompanied by shipping papers (if you can
safely get close enough!) which contain the proper shipping name, the four-digit ID number and other
important information about the hazards of the material.

Details of the placards and emergency response procedures can be found in the comprehensive DOT
Emergency Response Guidebook, copies of which may be available for review at your local CD,
police, sheriff or fire department. You may also want to consult your Local Emergency Planning
Committee (LEPC) or State Emergency Response Commission (SERC) concerning what role Amateur
Radio might have in your local plan. For more information about hazardous materials in general,
contact FEMA, Technological Hazards Division, Federal Center Plaza, 500 C St, SW, Washington,
DC, 20472 (202) 646-2861.