GHS Pictograms Explained: What Each Symbol Means

OSHA requires eight GHS pictograms on hazardous chemical labels under 29 CFR 1910.1200, Appendix C: the flame (flammables), flame over circle (oxidizers), exploding bomb (explosives), gas cylinder (gases under pressure), corrosion (corrosives), skull and crossbones (acute toxicity), exclamation mark (irritants/sensitizers), and health hazard (carcinogens and other chronic effects). Each is a black symbol on a white background inside a red, diamond-shaped frame. A ninth international symbol — the Environment pictogram (GHS09) — is not OSHA-required because environmental hazards fall to the EPA, not OSHA. This guide breaks down every symbol with the hazards it covers, real construction chemicals, required PPE, and the precautions each one demands.

Understanding GHS Pictograms

GHS pictograms are standardized hazard symbols used worldwide to communicate chemical dangers. Each pictogram is a square set on a point with a red frame, a white background, and a black symbol. Per Appendix C to 29 CFR 1910.1200, the red frame must be "sufficiently wide" to be clearly visible, and a red frame with no symbol inside it is prohibited. Learning to recognize these symbols is essential for every worker who handles hazardous chemicals.

OSHA requires eight pictograms on hazardous chemical labels under 29 CFR 1910.1200, Appendix C. A ninth GHS pictogram — the Environment (aquatic toxicity) symbol — is part of the international GHS but is not required by OSHA, because environmental hazards fall outside OSHA's jurisdiction. Its use on US labels is voluntary, and it is included below for awareness only.

Note on the images below: the symbols in this article are described in text/emoji form for quick reference only. On a real label, each pictogram must be a compliant black symbol on a white background inside a red frame — emoji, clip-art, and monochrome substitutes are not OSHA-compliant. Use the GHS Label Generator to produce compliant pictogram images.

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: The Eight OSHA Pictograms (Plus the Voluntary Ninth)

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

Flammable-liquid category guide (29 CFR 1910.1200 App B.6.1 / 1910.106):

OSHA defines flammable-liquid categories by flash point — and, for the two most volatile categories, also by boiling point. Note that Category 1 and Category 2 share the same flash-point cutoff (< 73.4 °F); they are split by initial boiling point, not flash point.

A liquid is a "flammable liquid" under OSHA only if its flash point is at or below 199.4 °F (93 °C). The flame pictogram (GHS02) is required for flammable liquids in Categories 1–4.

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

Note on Chemicals Under Pressure: HCS 2024 added a separate hazard class, Chemicals Under Pressure (Appendix B.3.2), under the Rev-7-aligned 2024 rule. It is its own class, not a gas-cylinder sub-type — but it does carry GHS04 on all three of its categories. Appendix C adds the flame on top for the flammable Categories 1 and 2, and Category 3 carries the gas cylinder alone. Do not confuse this with an Aerosol Category 3, which carries no pictogram at all. See the dedicated note below.

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)

HCS 2024 addition (Appendix B.3.2) — Chemicals Under Pressure: HCS 2024, which aligns primarily with GHS Revision 7, added Chemicals Under Pressure as a distinct hazard class (Appendix B.3.2). It covers liquids or solids pressurized with a gas at 200 kPa (gauge) or above that are not aerosols and not compressed gases. Products like pressurized spray cleaners, foam sealants, and certain adhesive applicators may now fall into this class. The pictogram(s) required depend on the product's flammability sub-classification (flame and/or gas cylinder) — it does not automatically use GHS04.

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:

Inhalation cutoffs differ by physical form. Under Appendix A to 29 CFR 1910.1200, gases are expressed in ppmV, vapors in mg/L, and dusts/mists in mg/L, each with its own numeric cutoffs; the column above shows the vapor (mg/L) values. Always check the specific Appendix A criteria for the form involved.

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 (Not OSHA-Required — Voluntary)

Important: This is the one GHS pictogram OSHA does not require. Environmental hazards fall outside OSHA's jurisdiction, so GHS09 is voluntary on US labels (manufacturers often include it for global consistency). It is presented here for awareness.

Hazard categories. Read these as UN GHS categories, not OSHA ones — OSHA's Appendix C contains no aquatic or environmental hazard class at all, which is precisely why GHS09 is voluntary here. Under the UN GHS the symbol is allocated to the more severe end of the scale only:

• Hazardous to the aquatic environment — Acute Category 1
• Hazardous to the aquatic environment — Chronic Categories 1 and 2

Chronic Categories 3 and 4 carry a hazard statement but no pictogram. So a product can be classified as an aquatic hazard and still, correctly, show no dead-fish symbol — if you see the statement without the symbol on a supplier label, that is not necessarily an error.

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, OSHA's precedence rules (29 CFR 1910.1200 Appendix C.4) mean certain pictograms take precedence and others can be dropped:

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.

When a hazard has no pictogram at all

Here is the training point that surprises people: not every hazard class gets a pictogram. Some carry only a signal word and a hazard statement — no red diamond. The clearest construction example is a Category 4 flammable liquid (flash point 140–199.4 °F, such as diesel or many mineral spirits): OSHA labels it "Warning" with the hazard statement "Combustible liquid" and no flame pictogram, because GHS reserves GHS02 for the more volatile Categories 1–3. Several mild irritation and lower-tier categories work the same way — a signal word without a symbol.

The lesson for your crew is blunt: the absence of a red diamond does not mean the absence of a hazard. A worker scanning only for pictograms will walk right past a combustible-liquid drum that is perfectly capable of a flash fire. Train people to read the signal word and hazard statements, not just the symbols — the pictograms are the fastest cue, but they are not the whole label.

HCS 2024 (GHS Rev 7) Changes Affecting Pictograms

OSHA's updated Hazard Communication Standard — the HCS 2024 final rule, which aligns primarily with GHS Revision 7 — introduces several changes that affect which pictograms a product carries:

1. New "Chemicals Under Pressure" class (Appendix B.3.2) — A distinct hazard class for liquids or solids pressurized with a gas that are not aerosols and not compressed gases. Per Appendix C, all three categories carry GHS04 (gas cylinder); the flammable Categories 1 and 2 add GHS02 (flame), and Category 3 carries the gas cylinder alone. Signal word: Danger for Cat 1, Warning for Cats 2 and 3.
2. New aerosol Category 3 (non-flammable) — Aerosols are now classified in Categories 1–3 (Appendix B.3). Appendix C gives Categories 1 and 2 the flame pictogram and gives Category 3 no symbol at all — only "Warning" and H229, "Pressurized container: may burst if heated." Two Category 3s, opposite treatment: the chemical under pressure gets the gas cylinder, the aerosol gets nothing. That pairing is the single easiest thing to get wrong in HCS 2024.
3. Desensitized Explosives (Appendix B.17) — A new physical-hazard class; certain products in this class use GHS02 (flame) rather than GHS01 (exploding bomb), depending on category.
4. Small container labelling (29 CFR 1910.1200(f)(12)) — Added by HCS 2024 for shipped containers only. Where a full label is not feasible, a small container (≤ 100 ml) may carry the product identifier, pictogram(s), signal word, supplier contact, and a statement that full label information is on the outer package; a very small container (≤ 3 ml) may carry the product identifier alone. This is a manufacturer/shipped-container provision — it does NOT apply to in-house workplace/secondary container labels (f)(6).

The HCS 2024 compliance deadlines are phased: for substances, manufacturers, importers, and distributors must comply by May 19, 2026 (29 CFR 1910.1200(j)(2)(i)) and employers by November 20, 2026 (29 CFR 1910.1200(j)(2)(ii)); for mixtures, manufacturers by November 19, 2027 and employers by May 19, 2028.

→ Check your labels: GHS Rev 7 Transition Wizard · Hazard Communication Standard 1910.1200

What's the Penalty for Missing or Wrong Pictograms?

Omitting a required pictogram — or using a non-compliant one (no red frame, black-and-white, emoji/clip-art, or an empty red frame) — is a labeling violation under 29 CFR 1910.1200(f), and Hazard Communication ranked second on OSHA's FY2025 list of most-cited standards. A serious citation can run up to $16,550 (the 2026 maximum, unchanged from 2025 — there was no inflation increase), and willful or repeated violations up to $165,514. Construction employers are covered through 29 CFR 1926.59, which adopts the 1910.1200 standard by reference.

By contrast, voluntarily adding the GHS09 environment pictogram carries no OSHA penalty — it is expressly permitted. The only real mistake with GHS09 is treating it as required.

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 the eight OSHA-required symbols — and ideally the voluntary ninth (Environment) as well — 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.

What to do next

1. Audit incoming labels against SDS Section 2 (Hazard Identification) — confirm every required pictogram is present, properly red-framed, and not reduced to illegibility.
2. Fix workplace and secondary containers, the most commonly cited HazCom gap — generate compliant ones with the GHS Label Generator.
3. Train your crew to recognize all eight symbols and the immediate response each demands — a quick Toolbox Talk does the job, and document it with a HazCom Training Record.
4. Track the HazCom 2024 deadlines — the employer compliance date for substances is November 20, 2026 (29 CFR 1910.1200(j)). See the Hazard Communication Standard 1910.1200 overview.

Note: This is general guidance, not legal advice. OSHA-approved State Plans may have their own HazCom requirements that are at least as effective as the federal standard; verify your state's rules.

Related: GHS Labels hub · The 8 OSHA Pictograms vs the 9 GHS Pictograms · GHS Label Requirements Complete Guide · Secondary Container Labels · Complete HazCom 2026 Guide · Print Compliant GHS Labels

Sources & verification: 29 CFR 1910.1200 Appendix C (pictograms), Appendix A (acute toxicity criteria), Appendix B (physical hazards) and paragraph (f) (labels); flammable-liquid categories per Appendix B.6.1 and 29 CFR 1910.106; construction adoption via 29 CFR 1926.59; penalty maximums per 29 CFR 1903.15(d) (2026); HCS 2024 deadlines per 29 CFR 1910.1200(j). Facts verified against the HazComFast regulatory source of truth (ghsClassification, hcsDeadlines, oshaPenalties), last verified 2026-06-26. Not legal advice.