Under the auspices of the U.S. Department of Transportation, hazmat placards are used in transportation. The U.S. has nine classes of associated hazardous materials. Training is available through many employers and is required through the Occupational Safety and Health Administration if employees are to come in contact with a hazardous material.
As of October 31, 1988, the Workplace Hazardous Materials Information System (WHMIS) is used in Canada to provide an education and communication standard when dealing with hazardous materials. Different symbols are provided for Classes A through F of hazardous materials. Training in the WHMIS is available through in-person classes and computer training modules.
Intuitive hazmat symbols are more likely to be understood than those that bear little relation to the substances they identify. A 2003 study by the Department of Industrial Engineering at Da-Yeh University found that the symbol's design in hazmat symbol training and labeling was a "significant factor for comprehension."