GHS hazard statement
H334: May cause allergy or asthma symptoms or breathing difficulties if inhaled
- H334
- Health hazards
- Danger
H334 means “May cause allergy or asthma symptoms or breathing difficulties if inhaled”. It is a GHS hazard statement for Sensitization, respiratory (Category 1, 1A, 1B), shown with GHS08 under the signal word “Danger”.
Hazard class and category
| Hazard class | Category | Pictogram | Signal word | UN transport class |
|---|---|---|---|---|
| Sensitization, respiratory | Category 1, 1A, 1B |  | Danger | — |
What H334 means
A respiratory sensitizer is a substance that causes hypersensitivity of the airways after inhalation. Later exposure can trigger asthma-like symptoms or breathing difficulties.
Breathing the dust, vapor or mist can lead to an allergy of the airways. Once sensitized, a person may react to very small amounts.
What to do
Avoid breathing dust, fumes, vapor or mist. Use ventilation or local exhaust and wear respiratory protection where the SDS says to. If breathing problems occur, move to fresh air and get medical attention.
This is general guidance for the hazard class. The safety data sheet for your product always takes precedence.
Precautionary statements for H334
The GHS lists these precautionary statements for this hazard. Which ones appear on a label depends on the supplier's classification.
| Code | Statement |
|---|---|
| P233 | Keep container tightly closed. |
| P260 | Do not breathe dust/fume/gas/mist/vapors/spray. |
| P271 | Use only outdoors or in a well-ventilated area. |
| P284 | [In case of inadequate ventilation] Wear respiratory protection. |
| P304+P340 | IF INHALED: Remove person to fresh air and keep comfortable for breathing. |
| P342+P316 | If experiencing respiratory symptoms: Get emergence medical help immediately. |
| P403 | Store in a well-ventilated place. |
| P501 | Dispose of contents/container to ... |
Chemicals carrying H334
4 chemicals in our database. Classification comes from each chemical's primary GHS source, so a supplier's SDS may differ.
H334 frequently asked questions
What does H334 mean?
H334 means "May cause allergy or asthma symptoms or breathing difficulties if inhaled". It is a GHS hazard statement in the health hazards group, covering Sensitization, respiratory (Category 1, 1A, 1B).
Which pictogram goes with H334?
H334 is shown with GHS08 (Health Hazard).
What signal word goes with H334?
The signal word for H334 is "Danger".
Which precautionary statements go with H334?
The GHS data lists 8 precautionary statements for H334, including P233, P260, P271, P284, P304+P340. They cover prevention, response, storage and disposal. The full list is on this page.
Hazard statements describe the hazard of a classified substance or mixture. The classification of a specific product can differ, so use the supplier's SDS.
https://pubchem.ncbi.nlm.nih.gov/ghs/ghscode_10.txt (UN GHS Revision 10, retrieved 2026-10-12)