Independent learning reference, not workplace-specific training or a product safety instruction. Use the current label, SDS and your employer’s procedures for the actual product.
Try original hazard-classification questions →A group is not a class or a category
Read classification as a hierarchy. “Health” is broad; “acute toxicity” identifies a particular concern; the category adds a division within that concern. Do not answer a question about groups with a list of pictograms.
| Level | What it tells you | Example |
|---|---|---|
| Group | Broad family | Physical or health |
| Class | Kind of hazard | Flammable liquids or acute toxicity |
| Category | Division within a class | Category 1, where that class uses it |
Compare the two groups
A product can have more than one classification. Do not force it into a single box based on the first symbol you notice. Check every listed hazard before considering how it is used.
| Group | Study examples |
|---|---|
| Physical | Flammability, oxidizing properties, gases under pressure, corrosion of metals |
| Health | Acute toxicity, skin effects, sensitization, cancer-related hazards |
How to read a category number
Within the same hazard class, a lower category number generally identifies a more severe hazard. Do not compare category numbers across different classes. A number alone does not tell you how to handle a product.
Source: CCOHS — Hazard classes and categories ↗Original classification exercise
Imagine a study card that lists “Flammable liquids — Category 2” and “Eye irritation — Category 2”. The repeated number does not mean the hazards are equivalent. You need the class name to understand what each category refers to.
- “Flammable liquids” belongs with physical hazards.
- “Eye irritation” belongs with health hazards.
- Both lines matter; the first does not cancel the second.
- A classification is not a complete handling instruction. Consult the product SDS and the workplace procedure.
Avoid these common mix-ups
If a question asks for the two groups, answer physical and health. If it asks about a specific product, read the full classification rather than counting symbols. The GHS environmental group was not adopted as a WHMIS hazard group, although environmental information can appear on a label or SDS.
Source: CCOHS — Hazard classes and categories ↗A short review method
Take an original quiz question you missed and write three lines: the broad group, the specific class and any category named. Explain the difference aloud without looking at the answer choices. Then open a different question to check whether you can apply the distinction.
For workplace learning, ask where the SDS is kept and how to identify the matching product. Do not use a practice example to select protective equipment or decide whether incompatible products can be stored together. Those decisions depend on the actual product and workplace procedures.