What does the blue section of the NFPA 704M signal?

The blue section of the NFPA 704M label indicates the health hazard associated with a material. The NFPA (National Fire Protection Association) labeling system uses a diamond shape divided into four quadrants—each representing different types of hazards. The blue section specifically addresses the level of risk posed to human health, with a rating scale from 0 to 4.

A rating of 0 signifies no health hazard, while a rating of 4 indicates a severe health hazard, meaning that exposure could result in large-scale damage or death. This system allows emergency responders and others to quickly assess the potential health risks of materials in a controlled environment, such as during a fire or chemical spill situation. Understanding the significance of the blue section helps ensure effective safety measures and emergency response planning, particularly in industries that handle hazardous materials.