|  | Public Health Safety | Public Health

About WHMIS Symbol

WHMIS is the acronym for Canada’s Workplace Hazardous Materials Information System. WHMIS symbols and classifications are national standards designed to help the population easily identify hazardous substances. The system includes criteria for biohazards, chemical, acute and health hazards. There are eight symbols to identify hazardous materials. A material may have more than one symbol for identification if it has multiple properties.

  1. Class A

    • The symbol for compressed gas, Class A, is an outline of a cylinder inside a circle. Compressed gases may be under pressure or chilled within a cylinder. Pressurized gas may explode due to increased temperature or proximity to fire. If the chilled gas leaks it may cause frostbite if in contact with skin. Oxygen is an example of a compressed gas.

    Class B

    • The symbol for flammable and combustible materials, Class B, is an image of a flame with an underline inside a circle. A flammable material will burn or flame at temperatures below 100 degrees F or 37.8 degrees C , or if they burn when in contact with air or water. A combustible material needs to be heated above 100 degrees F or 37.8 degrees C before catching on fire. Propane is an example of a Class B material, which includes solid, liquid and gaseous forms.

    Class C

    • The symbol for oxidizing materials, Class C, is the “O” shape with a flame on top, inside a circle. Oxidizing materials are inherently flammable but aid other substances in catching fire, due to the presence of oxygen. Oxidizers may be solid, liquid or gas. A common Class C material is oxygen.

    Class D

    • The symbol for materials causing immediate and serious toxic effects, Class D-Division 1 (D-1), is the skull and cross bones image inside a circle. These materials, such as carbon monoxide, may cause immediate effects such as burns, loss of consciousness, coma or death and may also cause long-term effects that go unnoticed for years.

      The symbol for materials causing other toxic effects, Class D-Division 2, is the image of a “T” that is tapered like an exclamation point (!) at the bottom, inside a circle. D-2 is subdivided into very toxic (D2A) and toxic (D2B). D2A materials may cause cancer, allergies, reproductive issues or genetic changes, and may have long-term toxic effects. D2B materials may cause skin or eye irritation and may also have long-term side effects.

      The symbol for biohazardous infectious materials, Class D-Division 3 (D-3), has a little circle in the middle, surrounded by a bigger circle, which is overlaid by three “C”s joined together, all within a circle. Bacteria, viruses, fungi, parasites and any tissues or fluids in contact with those materials are all considered biohazardous infections materials.

    Class E

    • The symbol for corrosive materials, Class E, is a circle which contains the image of one test tube pouring a liquid onto a metal bar and another test tube pouring a liquid onto a hand, with miniature lightning bolts between the test tubes and the bar or hand. These materials, such as ammonia gas, can cause permanent burns to human tissue.

    Class F

    • The symbol for dangerously reactive materials, Class F, is the letter “R” underneath the image of a test tube with miniature lightning bolts emanating from the top, all within a circle. These unstable materials, such as piric acid, exhibit three different properties: vigorous reactions with water to make toxic gas; reaction with itself if the substance is shocked or if the temperature or pressure is increased; and if the substance can break down, become condensation, or join to itself.

Public Health - Related Articles