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Workplace Safety
Never Mix Cleaning Chemicals
Why bleach must never meet acid or ammonia cleaners, and what to do if it does.
Free to download and print. No sign-up.
Why you need it
Mixing bleach with an acidic cleaner, such as a descaler, can release chlorine gas, and mixing it with an ammonia cleaner can release other harmful gases. Both can seriously harm breathing.
COSHH requires employers to control exposure to hazardous substances, and a clear rule at the point of use helps prevent accidents.
What it’s for
The two dangerous combinations, bleach with acidic cleaners and bleach with ammonia cleaners, how to use one product as directed, and what to do if products mix: stop, get to fresh air, keep others away, tell the supervisor and call 999 for serious breathing difficulty.
How to use it
- Put it in the chemical store and above the sink or area where products are diluted.
- Keep each chemical in a clearly labelled container and never decant into unlabelled bottles.
- Rinse surfaces and buckets between different products so residues cannot react.
- Make sure staff know to ventilate and leave the area if fumes appear.
- Cover it at induction alongside your COSHH assessments.
Next step: try the free practice course
COSHH Awareness is free to try: a short practice course with quick tests, no card needed.
Try it free →