HP1: Explosive
Waste that can explode or set off a dangerous chemical reaction, such as pyrotechnics or self-reactive material.
What HP1 means
HP1 covers waste that can, through a chemical reaction, give off gas at a temperature, pressure and speed that damages its surroundings. That includes pyrotechnic waste, explosive organic peroxides and explosive self-reactive waste. It's one of the few properties decided by testing instead of by adding up percentages.
How WM3 decides a waste is HP1
There are no concentration limits for HP1. If a waste holds a substance with one of these hazard statements, it is tested where that's appropriate and proportionate, or assumed to be HP1. A waste mixture or article already known to be explosive is HP1.
| Hazard statement | Hazard class |
|---|---|
| H200 | Unstable explosive |
| H201, H202, H203, H204 | Explosive, divisions 1.1 to 1.4 |
| H240 | Self-reactive or organic peroxide, type A |
| H241 | Self-reactive or organic peroxide, type B |
Organic peroxides of types C to F (H242) count towards HP3, flammable, instead. H205 (may mass explode in fire) and EUH001 (explosive when dry) don't make a waste HP1, but they can make it HP15.
WM3 sets out when a waste holding H240 or H241 organic peroxides needs no HP1 assessment, based on its hydrogen peroxide and available oxygen content (WM3 page C4).
What it changes when the waste moves
A waste needs only one hazardous property to be hazardous waste. In England and Wales it then moves on a hazardous waste consignment note in place of a waste transfer note, and the note goes with the load to the site that receives it.
On Digital Waste Tracking, the site that receives a hazardous load records its HP codes alongside the EWC code (the six-digit code from the List of Wastes that says what a waste is).
Sources
- WM3: Waste classification technical guidance (v1.2.GB): Appendix C1, pages C3 to C5
- Annex III to the Waste Framework Directive (HP1 to HP15)
- GOV.UK: Hazardous waste consignment notes
- The Digital Waste Tracking (England) Regulations 2026: the paragraphs on hazardous properties and POPs, 15 and 16
This page explains the rules. Check the waste itself against WM3 before it moves.
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