What does the first digit in the NFPA label blue quadrant indicate?

The first digit in the NFPA label blue quadrant represents the health hazard rating. The NFPA (National Fire Protection Association) labeling system uses a diamond shape with four quadrants, where each quadrant indicates a specific type of hazard: health, flammability, reactivity, and specific hazards.

In this system, the blue quadrant specifically relates to health hazards, with a scale ranging from 0 to 4. A rating of 0 indicates that the material poses no health hazard, while a rating of 4 signifies a severe health risk. This helps first responders quickly assess the potential health risks associated with exposure to the hazardous material, ensuring they can take appropriate precautions and protective measures during an emergency response.

The other quadrants of the label address different aspects of hazard, such as flammability and reactivity, but the blue quadrant's focus on health hazards is crucial for understanding how to protect oneself and others in the event of an incident involving hazardous materials.