What is used to warn people about hazardous materials? Question What is used to warn people about hazardous materials? Answers Placards Flashing lights Color-coded pieces of tape License plate stickers Explanation Diamond-shaped warning signs, called "placards," are placed on the outside of a vehicle carrying hazardous materials to serve as a warning. This questions appears in the following tests: Maryland HazMat Nevada HazMat North Dakota HazMat North Dakota HazMat South Carolina HazMat
