Clues for hazardous materials recognition, identification, and classification are markings and colors on packaging and pipelines. Examples of clues personnel should look for when responding to an incident include:

• Color codes
• Container specification numbers
• Signal words. These can include but are not limited to, any facility markings required by NFPA 704 or other regulations such as Waste, Hot, Compressed Air, Confined Spaces, etc.
• The content’s name and associated hazards
• Hazard communication markings
• Piping color-code systems