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The importance of WHMIS hazard labelling in the workplace

The Workplace Hazardous Materials Information System, or WHMIS for short, is a comprehensive plan for providing information on the safe use of hazardous materials and chemicals commonly found in Canadian workplaces. Developed by a tripartite committee of government, industry, and labour representatives, WHMIS safety regulations provide workers with the necessary knowledge and tools needed to maintain a safe working environment.

Why WHMIS labels are important:
WHMIS is designed to provide suppliers, employers, and workers with important handling instructions and safety precautions pertaining to hazardous materials. The label on a hazardous material is a crucial source of information and a major means of communication.
Types of WHMIS hazard warning labels:
Hazardous materials should be marked using two types of WHMIS labels:

  • Supplier labels
  • Workplace labels

The supplier label is attached to the container when it arrives at the workplace. The workplace label is attached to the container in the workplace in case no supplier label is available, or the material has been transferred from a larger container.

How to recognize WHMIS hazard symbols:
There are eight classes of hazard symbols used on WHMIS labels. Employers are required to train workers to recognize these symbols and know what each means. These classes are:

  • Class A: Compressed Gas
    This class of hazardous material includes compressed gases, dissolved gases, and liquefied gases.
  • Class B: Flammable and Combustible Material
    This class includes solids, liquids, and gases that are capable of igniting in the presence of a spark or open flame.
  • Class C: Oxidizing Material
    These hazardous materials increase the risk of fire if they come in contact with Class B (flammable or combustible) materials.
  • Class D: Poisonous and Infectious Material – Division 1: Materials Causing Immediate and Serious Toxic Effects
    Exposure to these hazardous materials can cause death or immediate injury.
  • Class D: Poisonous and Infectious Material – Division 2: Materials causing other Toxic Effects
    Exposure to these hazardous materials can cause life-threatening and serious long-term health problems. Immediate reactions can also occur in a person who is repeatedly exposed to small amounts.
  • Class D: Poisonous and Infectious Material – Division 3: Biohazardous Infectious Material
    These materials contain harmful micro-organisms that have been classified into Risk Groups 2, 3, and 4 by the World Health Organization and/or the Medical Research Council of Canada.
  • Class E: Corrosive Material
    Exposure to this class of hazardous material, which includes acid and caustic materials, can destroy the skin or eat through metals.
  • Class F: Dangerously Reactive Material
    These products may explode or self-react dangerously upon standing or when exposed to physical shock, like increased pressure or temperature, or when exposed to water.