2.2 Pictograms: eight symbols and four precedence rules

1 How a pictogram is constructed

Appendix C, paragraph C.2.3.1: pictograms shall be in the shape of a square set at a point and shall include a black hazard symbol on a white background with a red frame sufficiently wide to be clearly visible.

The paragraph then adds a sentence that decides a common argument on receiving docks: a square red frame set at a point without a hazard symbol is not a pictogram and is not permitted on the label. Blank red diamonds — the pre-printed stock some suppliers used to buy in bulk, intending to fill them in later — are not allowed. If you see one on a container in your workplace, the label is defective.

Note also what the rule does not say. It fixes no minimum size in inches, and it does not require the frame to be a particular shade of red. “Sufficiently wide to be clearly visible” is a performance criterion, judged against the container it is on.

2 Eight symbols, not nine

Appendix C, paragraph C.2.3.2: one of eight standard hazard symbols shall be used in each pictogram. The eight are depicted in Figure C.1 of the appendix, and paragraph C.2.3.2 also notes that a pictogram using the exclamation mark symbol is presented in Figure C.2 for illustration.

Eight is the number that trips people up, because the wider United Nations GHS has nine symbols — the ninth being the environment pictogram, the dead fish and dead tree. That symbol appears nowhere in OSHA's mandatory appendix, because environmental hazards are not within OSHA's jurisdiction. A supplier may print it, and many do for international markets; OSHA neither requires it nor forbids it.

Those eight cover, broadly: serious longer-term health effects such as carcinogenicity, respiratory sensitization, reproductive toxicity and specific target organ toxicity (health hazard); flammables, self-reactives, pyrophorics, self-heating substances, substances emitting flammable gas in contact with water and organic peroxides (flame); lower-severity irritation, skin sensitization and acute toxicity category 4 (exclamation mark); gases under pressure (gas cylinder); skin corrosion, serious eye damage and corrosive to metals (corrosion); explosives, self-reactives and organic peroxides of the more severe types (exploding bomb); oxidizers (flame over circle); and severe acute toxicity (skull and crossbones).

The icons above are drawn from an ordinary web icon set to name the eight symbols. They are a mnemonic for this page, not a reproduction of Figure C.1 — the real symbols are the ones printed in the appendix and on your supplier's labels.

3 A pictogram appears once

Appendix C, paragraph C.2.3.4: pictograms may only appear once on a label. If multiple hazards require the use of the same pictogram, it may not appear a second time.

A product can easily be classified for skin sensitization, skin irritation and eye irritation all at once — three separate classifications, all pointing at the exclamation mark. The label carries one exclamation mark. The three hazard statements underneath it are what tell you there were three findings.

This is a small rule with a real consequence: you cannot count pictograms to count hazards. A container with two pictograms may carry six classifications. The hazard statements, and section 2 of the safety data sheet, are the complete account.

4 Precedence: when one pictogram silences another

Appendix C, paragraph C.2.1, is titled Precedence of Hazard Information, and it contains four rules. They exist so that a label does not simultaneously shout and murmur about the same thing.

Notice the shape of all four: the more severe indicator suppresses the milder one for the same kind of hazard. The exclamation mark can still appear on a corrosive product — if it is there for something other than skin or eye irritation, for example a skin sensitization that C.2.1.4 does not reach. Precedence is hazard-specific, not blanket.

5 The pictogram that is allowed but not required

Paragraph C.2.3.3 is a small exception worth knowing: the exclamation mark pictogram is permitted, but not required, for hazards not otherwise classified, as long as the words “Hazard Not Otherwise Classified” or the letters “HNOC” appear below the pictogram.

This is the only place in the label scheme where a hazard not otherwise classified can surface on a container at all — paragraph (f)(1) otherwise keeps them off. If you see an exclamation mark with HNOC written under it, the supplier has chosen to flag a real hazard that the GHS boxes do not cover, and section 2 of the safety data sheet is where the description lives.

6 Teaching pictograms so they survive the shift

Pictogram training fails when it becomes a memory test of eight images. It works when each symbol is attached to a decision the crew already makes.

Flame: where does this get stored, and what is it kept away from? Corrosion: which glove, and where is the eyewash? Gas cylinder: is it secured, and what happens if it is heated? Skull and crossbones: does anyone touch this without the ventilation running? Health hazard: is this a product where the harm shows up in years rather than minutes, and what does that change about routine exposure?

That framing also satisfies (h)(3)(iii) — the measures employees can take to protect themselves, including the specific procedures the employer has implemented — because each answer is about your site, not about the symbol.