Class 5 labels: oxidisers and organic peroxides (yellow, or red and yellow)
The package contains an oxidiser, which makes other things burn more fiercely (5.1: pool chlorine tablets, some fertilisers, hydrogen peroxide solutions), or an organic peroxide, which can decompose violently and burn (5.2: hardener paste for car body filler and resins).
Who puts it on the box
The sender (consignor).
How to read it
Keep it away from fuels, wood, paper and other flammables and from heat. Some organic peroxides must travel temperature-controlled.
What it does not promise
It does not promise the contents are stable when warm or mixed with other goods, and it does not say whether temperature control is required: the transport documents do.
A mark on a parcel is the sender’s statement about what is inside and how it should be handled. It is not a certificate that the parcel is packed safely, that anyone handled it as marked, or that your carrier accepts it: for what you may send, read the carrier’s own terms.
- What it looks like
- 5.1 oxidising substance: a flame over a circle on yellow, figure 5.1. 5.2 organic peroxide: a flame, top half red and bottom half yellow, figure 5.2.
- Regulation
- ADR 2025, 5.2.2.2.2, label models No. 5.1 and 5.2; UN Model Regulations 5.2.2.2.2
- Kind of mark
- A dangerous-goods mark or label from the UN Model Regulations, applied in Europe by ADR (road) and its sister agreements for rail and waterways, and on the same pattern by the US 49 CFR. It says the package holds dangerous goods.
- Also called
- Oxidizer label; Organic peroxide label; Yellow diamond
Related
Other marks with the same shape
Sources
Each document was fetched and read on the date shown. Written in our own words; quotations are the documents’ wording.
- Regulator guidance — Health and Safety Executive (UK regulator for the carriage of dangerous goods): Carriage of dangerous goods manual — Consignment procedures: marking and labelling of packages (ADR 5.2) — Package labels are the “hazard diamonds” of ADR 5.2.2 with the class number; specimen labels are in ADR 5.2.2.2.2 and sizes in 5.2.2.2.1.1; the consignor is responsible for marking and labelling. Checked 2026-09-27.
- Law adopting the same mark — US Government Publishing Office (govinfo), 49 CFR, edition of 1 October 2024: 49 CFR Part 172 Subpart E — Labeling (§§ 172.400–172.450, the hazard class labels) — §§ 172.426–172.427: the OXIDIZER label (yellow) and the ORGANIC PEROXIDE label, red top half and yellow lower half. Labels are at least 100 mm on each side with an inner border about 5 mm inside the edge (§ 172.407). Checked 2026-09-27.