GHS Pictograms Explained: What Each Symbol Means

Understanding GHS Pictograms

GHS pictograms are standardized hazard symbols used worldwide to communicate chemical dangers. Each pictogram is a red diamond-shaped border (rotated square) with a white background containing a black symbol. Learning to recognize these symbols is essential for every worker who handles hazardous chemicals.

Under OSHA's Hazard Communication Standard (29 CFR 1910.1200), pictograms must appear on:

• Primary container labels (from the manufacturer)
• Secondary container labels (workplace labels)
• Safety Data Sheets (Section 2: Hazard Identification)

Quick Reference: All 9 Pictograms at a Glance

GHS01: Exploding Bomb 💥

Hazard categories:

• Explosives (Divisions 1.1 – 1.4)
• Self-reactive substances (Types A & B)
• Organic peroxides (Types A & B)

Common construction chemicals: Certain adhesive primers, blasting agents, power-actuated tool cartridges

Required precautions:

• Keep away from heat, sparks, open flames, and hot surfaces — No smoking
• Ground and bond containers during transfer
• Use only non-sparking tools
• Store in a cool, well-ventilated, explosion-proof location
• Wear protective gloves, eye protection, and face protection

Training emphasis: Workers must understand that self-reactive substances can decompose explosively even without an external ignition source if exposed to heat or contamination.

GHS02: Flame 🔥

Hazard categories:

• Flammable gases (Category 1A, 1B, 2)
• Flammable aerosols (Category 1, 2, 3 — new Category 3 in GHS Rev 7)
• Flammable liquids (Category 1-4)
• Flammable solids (Category 1-2)
• Self-heating substances
• Pyrophoric substances (ignite spontaneously in air)
• Substances that emit flammable gases on contact with water

Common construction chemicals:

Required precautions:

• Keep away from heat, hot surfaces, sparks, open flames — No smoking
• Keep containers tightly closed
• Ground and bond containers when transferring
• Use explosion-proof electrical equipment
• Use only non-sparking tools
• Store in a cool, well-ventilated place away from sunlight

Flash point guide:

GHS03: Flame Over Circle ⭕

Hazard categories: Oxidizing gases, liquids, and solids (Category 1-3)

What makes oxidizers dangerous: They don't burn themselves, but they provide oxygen that makes other materials burn faster and more intensely. A fire involving oxidizers can be extremely difficult to control.

Common construction oxidizers: Hydrogen peroxide (high concentration), sodium hypochlorite (bleach concentrate), certain concrete curing compounds

Required precautions:

• Keep away from clothing and other combustible materials
• Keep away from heat — Take precautionary measures against static discharge
• In case of fire: Use appropriate extinguishing media (water may not be suitable for all oxidizers)
• Store separately from flammable/combustible materials

Critical safety note: Never mix oxidizers with flammable materials, organic matter, or reducing agents. The resulting reaction can be violent and uncontrollable.

GHS04: Gas Cylinder 🔵

Hazard categories:

• Compressed gases
• Liquefied gases
• Refrigerated liquefied gases
• Dissolved gases
• Chemicals Under Pressure (new GHS Rev 8 class, adopted by OSHA's HCS 2024)

Common construction gases: Compressed air, acetylene, propane, oxygen, nitrogen, argon (welding gases)

Required precautions:

• Store in a well-ventilated place
• Protect from sunlight — Do not expose to temperatures above 50°C (122°F)
• Use pressure-reducing regulators
• Secure cylinders upright and away from traffic
• Separate oxygen from fuel gases by at least 20 feet or a 5-foot firewall
• Use proper handling equipment (cylinder carts, not rolling)

GHS Rev 8 addition (adopted by HCS 2024) — Chemicals Under Pressure: This new hazard class covers liquids or solids pressurized with gas at 200 kPa or above. Products like pressurized spray cleaners, foam sealants, and certain adhesive applicators may now require this pictogram.

GHS05: Corrosion ⚗️

Hazard categories:

• Skin corrosion (Category 1, 1A, 1B, 1C)
• Serious eye damage (Category 1)
• Corrosive to metals (Category 1)

Common construction chemicals:

PPE Required:

• Chemical-resistant gloves (nitrile minimum, check SDS Section 8 for specific material)
• Safety goggles or face shield (not just safety glasses)
• Chemical-resistant apron or coveralls
• Emergency eyewash station within 10 seconds of use location

Training emphasis: Many workers don't realize that wet concrete is corrosive. Prolonged skin contact with wet cement causes "cement burns" — a serious chemical burn that develops slowly and may not be noticed until significant tissue damage has occurred.

GHS06: Skull and Crossbones ☠️

Hazard categories: Acute toxicity — Fatal or toxic by any route:

• Category 1-3 Oral (fatal/toxic if swallowed)
• Category 1-3 Dermal (fatal/toxic through skin contact)
• Category 1-3 Inhalation (fatal/toxic if inhaled)

Important distinction from GHS07: The skull and crossbones indicates chemicals that can kill or cause serious toxicity from a single exposure. GHS07 (exclamation mark) covers chemicals that are harmful (less severe) from single exposure.

Acute toxicity categories:

Required precautions:

• Do not eat, drink, or smoke when using
• Wash hands and face thoroughly after handling
• Use only outdoors or in well-ventilated areas with appropriate respiratory protection
• Wear protective gloves, clothing, eye protection, and face protection
• Store locked up
• Keep out of reach of unauthorized personnel

GHS07: Exclamation Mark ❗

Hazard categories:

• Acute toxicity, Category 4 (harmful)
• Skin irritation (Category 2-3)
• Eye irritation (Category 2A)
• Skin sensitization (Category 1, 1A, 1B)
• Specific target organ toxicity — single exposure, Category 3
• Ozone layer hazard

This is the most common pictogram on construction sites. It covers a broad range of "less severe but still hazardous" effects.

Common construction chemicals with GHS07:

• Most cleaning products (degreasers, general-purpose cleaners)
• Latex paint
• Adhesives and sealants
• Dust-generating products (joint compound, grout)
• Many treated lumber preservatives

Skin sensitization warning: A chemical marked as a skin sensitizer can cause permanent allergic reactions. Once sensitized, even tiny future exposures can trigger severe reactions. Epoxy resins and certain isocyanates are notorious construction-site sensitizers.

GHS08: Health Hazard 🫁

Hazard categories:

• Carcinogenicity (Category 1A, 1B, 2)
• Respiratory sensitization (Category 1, 1A, 1B)
• Reproductive toxicity (Category 1A, 1B, 2)
• Specific target organ toxicity — single exposure (Category 1-2)
• Specific target organ toxicity — repeated exposure (Category 1-2)
• Mutagenicity (Category 1A, 1B, 2)
• Aspiration hazard (Category 1)

Why this pictogram matters most for long-term health:

These are the "silent killer" hazards — effects that may not appear for years or decades after exposure. Workers may feel fine during exposure but develop cancer, lung disease, or reproductive issues later.

Common construction exposures:

Required precautions:

• Obtain special instructions before use
• Do not handle until all safety precautions have been read and understood
• Use respiratory protection as specified in SDS Section 8
• If exposed or concerned: Get medical advice/attention
• Store according to SDS requirements

→ Related: OSHA Silica Table 1 Control Plan

GHS09: Environment 🐟

Hazard categories:

• Hazardous to the aquatic environment — Acute (Category 1)
• Hazardous to the aquatic environment — Chronic (Category 1-4)

Construction relevance: This pictogram is particularly important on construction sites near waterways, storm drains, or environmentally sensitive areas.

Common construction chemicals with GHS09:

• Many petroleum-based products (diesel, motor oil, hydraulic fluid)
• Pesticides and wood preservatives
• Certain concrete sealers and coatings
• Paint thinners and solvents

Required precautions:

• Avoid release to the environment
• Collect spillage — do not wash into storm drains
• Dispose of contents/container according to local regulations
• Report spills to appropriate authorities if threshold quantities are exceeded

Regulatory overlap: Spilling a GHS09-designated chemical into waterways can trigger violations under the Clean Water Act, CERCLA (Superfund), and state environmental regulations — in addition to OSHA citations.

Pictogram Precedence Rules

When multiple hazards apply, certain pictograms take precedence:

This means: If a chemical is both fatal (GHS06) and an irritant (GHS07), only the skull and crossbones appears — because the more severe hazard communication takes priority.

GHS Rev 7 Changes Affecting Pictograms (2026)

The 2026 GHS Rev 7 updates introduce changes relevant to pictograms:

1. New "Chemicals Under Pressure" category — Uses GHS04 (gas cylinder) for products not previously requiring it
2. Non-flammable aerosol category — Some aerosol products may lose the GHS02 (flame) pictogram if reclassified as non-flammable
3. Desensitized Explosives — New hazard class using GHS01 (exploding bomb) for certain products
4. Small container exemptions — Containers ≤3ml may display only pictograms + product identifier (no full label required if SDS is accessible)

→ Check your labels: GHS Rev 7 Transition Wizard

Using Pictograms in Training

Effective pictogram training should:

1. Start visual — Post large pictogram posters in break areas and near chemical storage
2. Make it interactive — Have workers match pictograms to chemicals they actually use
3. Connect to action — For each pictogram, teach the immediate response (what PPE, what to do in a spill)
4. Test comprehension — Ask workers to identify pictograms on actual product labels during toolbox talks
5. Document everything — Use training records with specific topics covered

→ Create training content: Toolbox Talk Generator → Document training: HazCom Training Record → Create compliant labels: GHS Label Generator

Conclusion

GHS pictograms are a universal language for chemical safety. Every worker who handles, stores, or works near hazardous chemicals must recognize all nine symbols and understand what precautions each requires.

The key takeaway: pictograms are not decorations — they are critical safety information that can prevent injuries, illnesses, and fatalities. Invest in pictogram training, post references in visible locations, and verify that every container in your workplace has the correct pictograms displayed.

Related: GHS Label Requirements Complete Guide · Secondary Container Labels · Complete HazCom 2026 Guide · Print Compliant GHS Labels