HP1: Explosive
Waste which is capable by chemical reaction of producing gas at such a temperature and pressure and at such a speed as to cause damage to the surroundings.
What this usually means in practice
HP1 applies where the waste itself can explode or violently decompose, causing damage to the surroundings. It is typically relevant for pyrotechnic wastes, explosive organic peroxides, self-reactive substances and wastes known to contain classified explosives.
Definition
Exact definition wording taken from WM3 Appendix C / Annex III for this hazardous property.
waste which is capable by chemical reaction of producing gas at such a temperature and pressure and at such a speed as to cause damage to the surroundings. Pyrotechnic waste, explosive organic peroxide waste and explosive self-reactive waste is included
What to check when assessing this property
Use the official definition, composition data and waste-process knowledge together. These points are meant to help frame the assessment, not replace WM3.
- Check SDSs, process knowledge and technical data for explosive, self-reactive or organic peroxide classifications (H200–H204, H240, H241).
- Remember that conditional risks such as "explosive when dry" (EUH001) and "may form explosive peroxides" (EUH019) belong to HP15, not HP1.
- Where a mixture is known to be explosive, it must be assigned HP1 even if no single component carries a Table C1.1 hazard statement.
Notes
Additional context added where the official wording or WM3 guidance needs a short plain-English explanation.
- Pyrotechnic wastes, explosive organic peroxide wastes and explosive self-reactive wastes are included.
How to use this page
Hazardous properties explain why a waste may be hazardous. They sit alongside EWC classification and they do not replace formal WM3 assessment or site acceptance checks.
1. Start with the waste
Identify the likely EWC entry, the process that produced the waste and whether it is part of a mirror-entry assessment.
2. Check the hazard evidence
Use composition data, SDSs, testing, pH, flash point and process knowledge as relevant to the property in question.
3. Confirm the final outcome
Confirm the conclusion against WM3 and any permit-specific or site-specific acceptance requirements before relying on it.
Wording is based on Annex III of the consolidated Waste Framework Directive opens in a new tab and should be used alongside Waste classification technical guidance (WM3, 3rd edition, 2021) — GOV.UK opens in a new tab.