What does a blue square labeled '2' in the NFPA Diamond categorization indicate?

In the NFPA (National Fire Protection Association) Diamond categorization, a blue square indicates health hazards, and the number within the square illustrates the severity of the health risk. When the square is labeled with the number '2', it signifies a health hazard that may cause temporary incapacitation or significant irritation.

This means that exposure to the material can have acute effects that are significant but not necessarily life-threatening. In many cases, individuals may experience adverse health effects that require intervention or attention but would not be expected to have lasting harmful outcomes.

The distinction between the various levels of health hazard illustrates the importance of recognizing and responding appropriately to risks in laboratory environments, especially when working with flammable gases and chemicals that may have immediate effects on health.