WHMIS Hazard Class Guide

The Workplace Hazardous Materials Information System (WHMIS) is Canada’s national hazardous chemical standard. The WHMIS labels are used to warn individuals of hazardous chemical dangers. The WHMIS classification helps workers handle, transport and store potentially dangerous chemicals.

“WHMIS Classification System”

The Department of Health Canada created the WHMIS Classification on October 31, 1988. The French variation is called the Systeme D’Information Sur Les Matieres Dangereuses Utilisees Au Travail (SIMDUT). These hazardous chemical safety labels are used on boxes, packages and containers to identify the contents thereof.

The WHMIS provide useful information on material safety data sheets (MSDS). Some workers might not have a chemistry background and these safety labels can help them handle these items without incident. The WHMIS uses the following classes for its materials:

A is Compressed Gas
B is Flammable & Combustible
C is Oxidizing
D is Poisonous & Infectious
E is Corrosive
F is Reactive

Class A Compressed Gas includes fire extinguishers, propane and chlorine. It is important to keep these at moderate temperatures and avoid punctures. Class B Flammable is propane and gasoline. Some chemicals, like propane, might have multiple class listings.

Class C Oxidizing includes oxygen, hydrogen peroxide and bleach. Workers should not store these next to combustibles, like wood or flammables.

The Class D Poisonous has three subgroups – D1, D2 and D3 – these could be fatal to humans via inhalation or ingestion. Class D1 includes hydrogen sulphide and cyanide. Class D2 includes asbestos and mercury. Class D3 is for biohazards, such as salmonella, HIV or Hepatitis B.

Class E is for disinfectants and cleaners. The WHMIS Class F Reactive – benzoyl peroxide and epoxy resins – might cause fumes or explosions when mixed with water.

“WHMIS Symbols”

In order to make it easier for workers, police officers and doctors to identify the contents of a box, pictures are used. These WHMIS Symbols are generally black-and-white circles with different images, such as test tubes, flames or skull-and-cross-bones.

“Which Industries Need WHMIS Labels?”

The following industries should use the WHMIS: transportation, semiconductor, industrial, warehouse, cleaning, aerospace and health care. The companies can use the WHMIS classification for training purposes. If workers see one class, then they should get in the habit of treating it in the approved fashion.

Storage should be at the proper temperature, humidity and pressure levels. Some reactive chemicals should not be stored with one another. Many hazardous chemicals with WHMIS labels should not be stacked. These could fall to the ground, leading to a spill or explosion.

This WHMIS Hazard Class Guide can help workers select protective clothing – glasses, gloves and overalls. Emergency responders can use the WHMIS safety labels for first-aid and fire control. For more information, ICC Compliance Center may be a good place to gather additional resources.