These are the
diamond-shaped tags you see on
vehicles carrying chemicals and at chemical facilities. The standard for these tags comes from the
National Fire Protection Association and are designed to provide important information to
firefighters and other
rescue crews in the event of a
fire or other
emergency.
They are divided into 4 smaller colored dimonds, as follows:
The health, flammability, and reactivity sections each have a number from 0 to 4, which represents the danger levels according to a system similar to, but not identical to, the
HMIS ratings. In particular, the HMIS ratings are intended for
employee safety and so the health ratings consider
long-term effects, while the NFPA ratings do not.
The special code area may show a W in the case of chemicals that are highly reactive with water, or OX for the presence of oxidizing agents, or both.