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 hazard classes Appendix C assigns to it, examples you may meet on a construction site, and typical precautionary statements. The product's own label and SDS govern.

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 symbols: the pictograms shown in this article are the standard OSHA symbols. On a shipped label, each one must be one of the eight standard symbols, in black on a white background inside a red frame (Appendix C.2.3.1 and C.2.3.2); emoji or clip-art in place of the standard symbol does not meet that rule. The GHS Label Generator prints the standard symbols.

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

• Shipped container labels (from the manufacturer, importer or distributor): required, in red frames (29 CFR 1910.1200(f)(1)(iv) and Appendix C)
• Workplace (secondary) container labels: optional when you label with the product identifier plus other words, pictures or symbols under (f)(6)(ii), and a black border is allowed on in-house labels (OSHA directive CPL 02-02-079, section X.F.4.b)
• Safety Data Sheets (Section 2: Hazard Identification): the symbol, which may be reproduced in black and white, or its name (Appendix D)

Quick Reference: The Eight OSHA Pictograms (Plus the Voluntary Ninth)

GHS01: Exploding Bomb

Hazard categories (Appendix C):

• Explosives: unstable explosives and Divisions 1.1 to 1.4 (no pictogram is required for 1.4S small arms ammunition; Division 1.5 has no pictogram; Division 1.6 has neither pictogram nor signal word)
• Self-reactive substances (Types A & B)
• Organic peroxides (Types A & B)

On a construction site: explosives used for blasting. Check Section 2 of the SDS for the division.

Typical precautionary statements for explosives (Appendix C.4.14; the product's label and SDS govern):

• Keep away from heat, hot surfaces, sparks, open flames and other ignition sources. No smoking.
• Keep only in original packaging.
• Ground and bond container and receiving equipment, if the explosive is electrostatically sensitive.
• Do not subject to grinding, shock or friction, if the explosive is mechanically sensitive.
• In case of fire: explosion risk. Evacuate the area, and do not fight the fire once it reaches the explosives.
• Wear the protective equipment the supplier specifies, which can include hearing protection.

Training emphasis: Self-reactive substances are thermally unstable and can decompose violently even without air (Appendix B.8.1). Follow the storage temperature on the label and SDS.

GHS02: Flame

Hazard categories (Appendix C):

• Flammable gases, Categories 1A and 1B (Category 2 has no pictogram)
• Aerosols, Categories 1 and 2 (the new Category 3 has no pictogram)
• Flammable liquids, Categories 1 to 3 (Category 4 has no pictogram)
• Flammable solids, Categories 1 and 2
• Self-reactive substances and organic peroxides, Types B to F
• Self-heating substances
• Pyrophoric liquids and solids (ignite spontaneously in air)
• Substances that emit flammable gases on contact with water
• Desensitized explosives, all four categories
• Chemicals under pressure, Categories 1 and 2, with the gas cylinder

Common construction chemicals:

Flash points for the four solvents are the values on the linked chemical pages (NTP data); the mineral spirits range is ATSDR's for Stoddard solvent. Each of the four solvents boils above 35 °C, which is why they are Category 2 and not Category 1.

Typical precautionary statements for flammable liquids (Appendix C.4.19; the product's label and SDS govern):

• Keep away from heat, hot surfaces, sparks, open flames and other ignition sources. No smoking.
• Keep container tightly closed; ground and bond container and receiving equipment; use explosion-proof equipment; take action to prevent static discharge. Appendix C ties these to liquids that are volatile and may generate an explosive atmosphere.
• Use non-sparking tools, only where the liquid also has a very low minimum ignition energy, such as carbon disulfide.
• Store in a well-ventilated place. Keep cool.

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 1–3; Category 4 carries no pictogram (Appendix C.4.19).

GHS03: Flame Over Circle

Hazard categories (Appendix C): Oxidizing gases (Category 1); oxidizing liquids and solids (Categories 1 to 3)

What makes oxidizers dangerous: They are not necessarily combustible themselves, but they can cause or feed the burning of other materials, generally by giving off oxygen (Appendix B.4, B.13 and B.14). A fire involving oxidizers can be extremely difficult to control.

On a construction site: the oxygen cylinder of an oxy-fuel rig (an oxidizing gas, which also carries the gas cylinder) and concentrated hydrogen peroxide. Check Section 2 of the SDS for the classification of the product you have.

Typical precautionary statements (Appendix C.4.17, C.4.26 and C.4.27; the product's label and SDS govern):

• Keep away from clothing and other combustible materials.
• Keep valves and fittings free from oil and grease (oxidizing gases such as oxygen).
• Keep away from heat, hot surfaces, sparks, open flames and other ignition sources (oxidizing liquids and solids).
• In case of fire: use the extinguishing media the supplier names; for some oxidizers, water increases the risk.
• Store separately (Category 1 liquids and solids).

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

Flame or flame over circle: check what your screen draws

This difference decides storage. GHS02 marks what burns; GHS03 marks what makes other things burn harder. A label or a screen that swaps them puts an oxidizer next to the solvents. Check it on two products, one oxidizer and one flammable, on screen and then on the printed label.

In HazComFast, the pictograms come from the same official OSHA files on the product page, on the public page a QR code opens and on the printed Avery sheet, and a test fails if any of the nine files changes. The oxidizer and flammable symbols can't be confused, and the signal word keeps one color on every screen: Danger in red, Warning in amber.

GHS04: Gas Cylinder

Hazard categories (Appendix C):

• Gases under pressure: compressed, liquefied, refrigerated liquefied and dissolved gases
• Chemicals under pressure, all three categories (added to Figure C.1 by the corrections of January 8, 2026)

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)

What the label says (Appendix C.4.18): "Protect from sunlight. Store in a well-ventilated place." For a refrigerated liquefied gas, wear cold insulating gloves and either a face shield or eye protection.

What 29 CFR 1926.350 adds for cylinders on a construction site:

• Keep valve protection caps in place and secured ((a)(1)).
• Secure cylinders upright ((a)(9)), with a cylinder truck, chain or other steadying device while in use ((a)(7)).
• Move cylinders by tilting and rolling them on their bottom edges, and never drop or strike them ((a)(3)); remove the regulator and cap the valve first unless the cylinder is secured on a special carrier ((a)(6)).
• Store oxygen at least 20 feet from fuel-gas cylinders, or behind a noncombustible barrier at least 5 feet high with a fire-resistance rating of at least one-half hour ((a)(10)).
• Draw fuel gas through a pressure-reducing regulator ((d)(3)).

HCS 2024 addition (Appendix B.3.2): Chemicals Under Pressure: HCS 2024, which aligns primarily with GHS Revision 7, took Chemicals Under Pressure from GHS Revision 8 as a distinct hazard class (Appendix B.3.2). It covers liquids or solids pressurized with a gas at 200 kPa (gauge) or more at 20 °C, in pressure receptacles other than aerosol dispensers, that are not classified as gases under pressure. OSHA described these as products packed in refillable or non-refillable pressure receptacles of up to 450 liters, some of them used for spray applications (89 FR 44323). A product in an aerosol can is classified as an aerosol instead. All three categories carry the gas cylinder (GHS04); Categories 1 and 2 add the flame (Appendix C.4.16).

GHS05: Corrosion

Hazard categories:

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

Categories 1A, 1B and 1C share one row of Appendix C (C.4.4), so they carry the same label: Danger, "Causes severe skin burns and eye damage" and this pictogram. The category itself goes in Section 2 of the SDS. In HazComFast, the hazard statements on the SDS give the pictogram and the signal word, and when the statements alone don't settle the category, the product page says the SDS decides.

Common construction chemicals:

Protection (Section 8 of the SDS names the glove material and eye protection):

• Gloves of the material the SDS names; no single glove material suits every corrosive. For wet cement, OSHA's guide lists butyl or nitrile gloves (OSHA 3351).
• Chemical splash goggles, with a face shield over them where splashing is likely.
• Chemical-resistant apron or coveralls.
• Facilities for quick drenching or flushing of the eyes and body within the work area, for immediate emergency use (29 CFR 1926.50(g)). OSHA points to ANSI Z358.1 as guidance, which puts the eyewash on the same level as the hazard and no more than 10 seconds away (OSHA memo of October 18, 2010).

Training emphasis: Wet concrete is caustic. OSHA's portland cement guide warns that cement burns may not cause immediate pain, that much damage is done by the time a worker notices, and that the burn can get worse after contact ends (OSHA 3351).

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.

Typical precautionary statements for acute toxicity Categories 1 to 3 (Appendix C.4.1 to C.4.3; the product's label and SDS govern):

• Do not eat, drink or smoke when using this product.
• Wash thoroughly after handling.
• Use only outdoors or in a well-ventilated area, and wear respiratory protection where the label calls for it (inhalation hazards).
• Do not get in eyes, on skin, or on clothing; wear protective gloves and protective clothing (skin hazards).
• Store locked up.

GHS07: Exclamation Mark

Hazard categories:

• Acute toxicity, Category 4 (harmful)
• Skin irritation (Category 2)
• Eye irritation (Category 2A; Category 2B has no pictogram)
• Skin sensitization (Category 1, 1A, 1B)
• Specific target organ toxicity: single exposure, Category 3
• Hazards not otherwise classified, if the supplier chooses, with "HNOC" under the symbol (Appendix C.2.3.3)

The UN GHS also uses the exclamation mark for hazards to the ozone layer, a class OSHA did not adopt. The pictogram covers a broad range of "less severe but still hazardous" effects.

Products that may carry GHS07, depending on the formulation (check Section 2 of the SDS):

• Degreasers and general-purpose cleaners
• Some paints, adhesives and sealants
• Cement-based grouts and mortars
• Wood preservatives

Skin sensitization warning: A skin sensitizer "may cause an allergic skin reaction" (Appendix C.4.7). Once a worker is sensitized, small later exposures can set off the reaction again. Epoxy resins are a common example: bisphenol A diglycidyl ether, the main epoxy resin component, is classified H317 in the GHS classifications PubChem compiles.

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. Some manufacturers include it, which OSHA's directive allows as long as it does not get in the way of the required information (CPL 02-02-079). 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.

On imported products the symbol is common. It appears on 40% of the entries of the EU's official list of harmonised classifications, and our GHS hazard statement index shows, chemical by chemical, what the EU and Japan lists say and what changes on a US label.

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

Products whose SDS may show GHS09, depending on the formulation:

• Diesel fuel and some other petroleum products
• Pesticides and wood preservatives
• Some sealers, coatings, thinners and solvents

Typical precautionary statements under the UN GHS (not OSHA requirements):

• Avoid release to the environment
• Collect spillage, and do not wash it into storm drains
• Dispose of contents/container according to local regulations
• Report spills to the authorities where a reporting threshold is exceeded

Regulatory overlap: A spill into waterways can trigger duties under the Clean Water Act, CERCLA release reporting and state environmental rules, depending on the substance and the quantity.

Pictogram Precedence Rules

When multiple hazards apply, OSHA's precedence rules (29 CFR 1910.1200, Appendix C, C.2.1.2 to C.2.1.4) drop the exclamation mark in three cases:

This means: if a chemical is fatal if swallowed (GHS06) and harmful in contact with skin (acute toxicity Category 4), only the skull and crossbones appears for the toxicity. If the same chemical is also a skin irritant, the exclamation mark stays for the irritation, unless the label also carries the corrosion symbol or the health hazard symbol for respiratory sensitization.

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 above 140 °F and up to 199.4 °F; check Section 2 of the SDS): 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 easy to get wrong.
3. Desensitized Explosives (Appendix B.17): A new physical-hazard class. Appendix C.4.30 gives all four categories the flame (GHS02), not the exploding bomb (GHS01).
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, as necessary, by November 20, 2026 (29 CFR 1910.1200(j)(2)(ii)); for mixtures, manufacturers by November 19, 2027 and employers, as necessary, 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 from a shipped label, or using one that misses Appendix C.2.3 (no red frame, clip-art in place of the standard symbol, 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: OSHA's directive permits it as long as it does not get in the way of the required information (CPL 02-02-079). 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 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 that are not labeled, using 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: for substances, employers update workplace labels, the written program and training, as necessary, by November 20, 2026 (29 CFR 1910.1200(j)(2)(ii)). 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. Appendix C pictogram allocations and precautionary statements, Appendix B definitions, and 29 CFR 1926.350 and 1926.50(g) re-read on October 13, 2026, with OSHA directive CPL 02-02-079, OSHA publication 3351, the OSHA memo of October 18, 2010, and the NIOSH, CDC, ATSDR, CPWR and IARC sources named in the tables. Not legal advice.