Advanced Engineering is warning engineers to regularly check the labels and safety data sheets of cleaning chemicals advertised as suitable for indoor and outdoor use.

The air conditioning maintenance product manufacturer's warning has come after it noticed "the worrying chemical 'Risk Phrase' R34 (causes burns) on labels". The company said this showed one popular chemical marketed as 'universal' was in fact corrosive and officially classified as dangerous by the EU.

Technical director Colin Pratt said: “Using a heavy-duty corrosive chemical indoors will get things very clean – but the risks are simply unacceptable. That’s why responsible companies don’t market them that way.

“The law, and common sense, says risks at work must be as low as reasonably practical. That means every facilities manager and engineer needs to ensure the risks posed by any cleaning chemical are proportionate to the job it needs to do.

“You need to know what’s in the bottle. Whatever the advertising spin says, that should always involve checking small print – ideally, the Material Safety Data Sheet – very carefully, because some manufacturers are not very forthcoming about the actual risks involved, and some even vary their formulas without changing the brand.

“In some cases, it might come down to knowing the difference between Risk Phrases R36/38, an irritant, and R34, a corrosive, which is far nastier and should not usually be used indoors.”

Advanced Engineering said anyone confused about chemical risk assessment can call the company for "free, unbiased technical support" on 01256 460300.