Chemical stores are a look-but-do-not-touch area
A venue chemical store holds concentrated products, sometimes incompatible with each other, stored to rules the operator is responsible for maintaining. A cleaner sweeping that room should not be moving containers, wiping spills of unknown product or consolidating part-used drums. Doing so risks a reaction, an injury and a breach of the operator's own storage arrangement.
The realistic scope is the floor in clear areas, the door approach and reporting. Any spill, damaged container, missing label or product stored outside its bunding is reported to the operator immediately and not touched. Writing that instruction down is more useful than any frequency, because it tells an attendant what to do in the situation that actually matters. Recording the operator's own storage arrangements at the walkthrough also identifies whether any product is stored outside its bunding, which is worth raising early.
