U.S. Department of Transportation’s (DOT) Hazardous Materials Regulations define hazardous materials placarding and labeling requirements. Placards and labels are a clue that should be considered a definitive source of hazardous materials information. Placards and labels may be displayed, even if not required, if they conform to DOT requirements.

Placards and labels provide hazard identification by using:

• Hazard Class/Division number on the bottom of the placard/label (indicates the primary hazard)
  
• Colored background
  
• Respective hazard class symbol
  
• Hazard class description or a four-digit identification number, which is found in the center of the placard (hazard classes have specific placards)

Often responders rely on DOT labels, placards, and/or marking to identify a container’s contents in a facility setting. When a regulated package reaches its destination DOT no longer has authority, but containers are still required to maintain hazard information. OSHA regulation 29 CFR 1910.1201 “Retention of DOT markings, placards and labels” require that original labels, placards, and markings be maintained during storage and use.