WHMIS Pictograms Explained: All 9 Symbols and Meanings

Whether you cook in a restaurant, build a skyscraper, or work in a daycare, you will run into hazardous chemicals. Here is how to read the warning before you open the cap.

WHMIS stands for the Workplace Hazardous Materials Information System. It is Canada's national system for communicating hazards so that workers can go home safely at the end of the day. In 2015, Canada updated WHMIS to match the Globally Harmonized System (GHS). This update brought a set of universal warning images called pictograms. A pictogram is a graphic image that includes a symbol, a border, and a background colour, and its job is to give you a quick, visual warning about the dangers of a product before you even open the cap.

Most WHMIS pictograms look like a red diamond, a square set on a point, with a black image inside on a white background. One special Canadian pictogram uses a round black border instead. This guide breaks down all 9 Canadian WHMIS pictograms in plain English, shows how these warnings work in three real workplace scenarios, answers common questions, and ends with a quiz.

The 9 WHMIS pictograms explained

Here are the 9 official pictograms used in Canada. If you see one of these on a label, you need to pay attention.

1. Flame

What it looks like: A burning fire.
What it means: This symbol warns you about fire hazards. Products with this symbol can catch fire easily if they are exposed to a spark, heat, or an open flame.
Common examples: Gasoline, propane, aerosol sprays, and some strong cleaning solvents.
Safe handling: Keep these products far away from heat, hot surfaces, sparks, and open flames. Always store them in approved, fire-resistant cabinets, and never smoke near them.

2. Flame Over Circle

What it looks like: A letter O with flames coming out of the top.
What it means: This is the symbol for oxidizing hazards. Oxidizers do not necessarily burn by themselves, but they release oxygen. This extra oxygen can cause other materials to catch fire quickly and burn fiercely.
Common examples: Hydrogen peroxide, bleach, and certain pool chemicals or fertilizers.
Safe handling: Never store oxidizers next to flammable materials. If they mix, they can start an intense fire that is incredibly difficult to put out. Keep their containers tightly closed.

3. Gas Cylinder

What it looks like: A rolling pin or a metal tank bottle.
What it means: This warns you about gases under pressure. These are gases stored in a cylinder or a tank at very high pressure. If the tank is punctured, heated, or dropped, it could explode like a rocket. The gas inside might also be extremely cold, causing frostbite.
Common examples: Propane tanks, helium, oxygen tanks, and fire extinguishers.
Safe handling: Always secure gas cylinders upright with a chain so they do not fall over. Keep them away from heat, and never drag or drop them.

4. Corrosion

What it looks like: Two test tubes dripping liquid onto a metal bar and a human hand, burning a hole in both.
What it means: This product is corrosive. It can easily eat through and destroy metals. Worse, it can cause severe damage, severe skin burns, or permanent eye damage if it touches your body.
Common examples: Battery acid, heavy-duty oven cleaners, drain cleaners, and industrial degreasers.
Safe handling: You must wear serious protective gear. Always use heavy-duty chemical gloves, safety goggles, and sometimes a protective apron. If it gets on your skin, you must immediately find an emergency washing facility to flush the area with water.

5. Exploding Bomb

What it looks like: A bomb blowing up with lines bursting outward.
What it means: This warns of severe explosion hazards. Under Canadian law, this is used specifically for self-reactive substances and organic peroxides. These unstable chemicals might react violently, catch fire, or explode if they are heated, dropped, or mixed with the wrong thing. Regular explosives like dynamite are regulated by a different law in Canada, so you will not see this WHMIS symbol on them.
Common examples: Highly specialized chemical hardeners or resins used in manufacturing.
Safe handling: Handle these products very gently. Follow the Safety Data Sheet perfectly regarding exact storage temperatures and handling instructions.

6. Skull and Crossbones

What it looks like: A human skull with two crossed bones underneath.
What it means: This is the symbol for acute toxicity. It means the product is highly poisonous and could be fatal or toxic if you swallow it, breathe it in, or let it absorb through your skin. Even a tiny amount can cause extreme harm or death.
Common examples: Severe industrial pesticides, cyanide, and heavy toxic chemicals.
Safe handling: Never use this product without strict training. You will likely need a respirator, face shield, and fully covering protective clothing. Wash your hands intensely after use, and never eat or drink near these chemicals.

7. Health Hazard

What it looks like: A person's head and chest with a star-shaped crack in their chest.
What it means: This warns about serious, long-term (chronic) health effects. These products might cause cancer, damage your DNA, affect your ability to have children, or cause specific organ damage over time.
Common examples: Asbestos, lead, mercury, and certain chemical solvents.
Safe handling: Since you might not feel sick immediately, it is easy to ignore the danger. Do not. Always use proper ventilation, wear recommended masks or respirators, and avoid any direct skin contact to prevent the chemical from building up in your body over the years.

8. Exclamation Mark

What it looks like: A thick exclamation point.
What it means: This symbol is for less severe health hazards. It means the product might irritate your skin or eyes, cause an allergic skin reaction, or make you dizzy if you breathe in the fumes.
Common examples: General surface cleaners, some glues, and paints.
Safe handling: While it will not instantly destroy your skin like a corrosive product, you still need to be careful. Wear gloves, ensure the room has good airflow, and wash your hands after using it.

9. Biohazardous Infectious Materials

What it looks like: Three overlapping circles with a small circle in the middle, inside a round, black border.
What it means: This pictogram is unique to Canada. It does not have the red diamond border. It warns you about living organisms, like bacteria, viruses, or fungi, or their toxins that can cause disease in humans or animals.
Common examples: Used needles, blood samples, and contaminated waste in hospitals or labs.
Safe handling: Treat anything with this label as highly infectious. Use strict hygiene, wear medical-grade gloves, dispose of waste in special puncture-proof biohazard bins, and follow exact cleanup procedures.

Looking for the 10th symbol? Some sources reference a 10th, globally used pictogram for environmental hazards (a dead fish and a tree). Canada did not adopt this one into WHMIS, so you will not find it on this list. See the FAQ below for why.

Real-world case scenarios

To help you understand how WHMIS pictograms keep workers safe, let's look at three different industries.

Scenario 1: The daycare center

Sarah works at a busy daycare center. After the children go home, she needs to disinfect the bathrooms to prevent the spread of germs. She grabs a heavy-duty bathroom cleaner from the supply closet.

The hazard: Sarah looks at the supplier label and sees the Corrosion pictogram and the Exclamation Mark pictogram. The action: The symbols instantly tell Sarah that this chemical could burn her skin or irritate her lungs if she breathes it in in a small bathroom. Because of her WHMIS training, she knows exactly what to do. She puts on long rubber gloves, opens the bathroom window for ventilation, and ensures she does not splash the product into her eyes. If the product was in a large bucket and she poured it into a smaller spray bottle, she also knows she must create a new workplace label for the spray bottle so her coworkers know what is inside.

Scenario 2: The construction company

Mark is working on a high-rise construction site during the winter. He is tasked with welding metal beams together.

The hazard: Mark uses a welding cart that holds large metal tanks. He checks the label and sees the Gas Cylinder pictogram and the Flame pictogram. The action: These pictograms warn Mark that the gases are under extreme pressure and are highly flammable. Before starting his work, he uses heavy chains to secure the tanks tightly to the wall so they cannot fall over and break their valves. Because of the Flame symbol, he also ensures that sparks from his welding do not land anywhere near the tanks. Later, he uses a sealant that features the Health Hazard pictogram. Knowing this means long-term lung damage, he makes sure his protective respirator mask is perfectly fitted before opening the can.

Scenario 3: The restaurant kitchen

Chef Alex is closing down the kitchen after a busy Friday night. The deep fryer has thick, baked-on grease, so Alex reaches for the industrial degreaser.

The hazard: Alex notices the Corrosion symbol on the supplier label. The action: Even though Alex is tired and wants to go home, that symbol reminds him that the degreaser can cause permanent eye damage or eat through his skin. Instead of just using a rag, he puts on thick chemical-resistant gloves and safety goggles. While cleaning, a coworker accidentally cuts themselves. When cleaning up the blood, the coworker places the soiled bandages in a special bin marked with the round, black Biohazardous Infectious Materials pictogram so the garbage collectors know it contains potential human pathogens.

"Workers do not need to memorize a manual in the moment. They need to recognize a shape on a label fast enough to grab the right gloves before they open the container."

Samira AliCertified Public Health Inspector, 10+ years across Canada and the U.S.

Sources: Government of Canada: WHMIS Supplier Hazard Communication Requirements, WorkSafeBC: Chemical and Biological Substances, and Manitoba Workplace Safety and Health.

A note from our team. WHMIS regulations can vary by province and change over time. This guide is general information, not legal advice. Your provincial or territorial regulator sets the exact rules for your workplace. Spot something that needs updating? Email info@probeit.ca.