Ever wonder what the hazard symbols in the diamond placards on the sides of tank trucks are telling us? The signs are notifying us of the possible chemical hazards posed by the contents of the truck. The blue portion of the symbol represents health hazards. The yellow portion represents reactivity such as a tendency to explode. The red is flammability. The white portion is for special hazards such as dangerous reactivity with water. The higher the numbers the more dangerous the chemical. Use of this hazard symbol has been carried into the lab. It appears on wash bottles and other chemical containers. The standards for this symbol were developed and are maintained by National Fire Protection Association. The NFPA refers to this symbol as the Fire Diamond. The fire diamond was developed to inform emergency workers of possible hazardous materials. For more information about the standards used to develop this warning system please refer to the NFPA Website.