What type of hazard is indicated by a green placard?

The green placard is used to indicate a non-flammable gas. This classification is part of the standard placarding system established by the Department of Transportation (DOT) for identifying hazardous materials during transportation. Non-flammable gases include materials that do not burn or support combustion but may still pose various other hazards, such as toxicity or being under pressure.

In contrast, water reactive materials typically use a white placard with a blue border to denote their specific hazard, while flammable liquids are marked with a red placard. Oxidizers, which can enhance the combustion of other materials, are indicated by a yellow placard. Thus, the green placard is specifically associated with non-flammable gases, highlighting the importance of recognizing and adhering to proper hazard communication standards in the transportation and handling of hazardous materials.