Nobody opens a transport depot thinking of it as a chemical works. Then you count: brake cleaner aerosols, degreasers, diesel, oils, battery acid, paints and thinners, welding fume, brake and clutch dust, the cleaning cupboard. The Control of Substances Hazardous to Health Regulations - COSHH - apply to all of it, and they set a distinctive way of thinking: fix the substance first, the worker’s exposure last.
COSHH covers substances that can cause harm by how they are used or produced at work - not just the ones with orange hazard diamonds. Vapours, fumes, dusts and mists count, including dusts the work itself creates. The safety data sheet that suppliers must provide is the starting point for knowing what you actually have on the shelf, which is why the first COSHH failure in most workshops is not exposure - it is ignorance of what is in the building.
Before the assessment, HSE’s own framing is three questions:
The walk around the workshop with those questions - watching the mechanic spray brake cleaner into a drum, the painter mixing in the corner, the yard hand brushing dried mud - produces the substance list the assessment then works through.
Always try to prevent exposure at source first. HSE’s examples are practical:
Only what cannot be prevented gets controlled, and control has a legal yardstick: adequate means as low as is reasonably practicable. Concretely: all control measures in good working order; exposures below the Workplace Exposure Limit where one exists; and for substances causing cancer, asthma or genetic damage, exposure reduced to as low a level as possible - the limit is not a target for those, it is a floor on ambition.
COSHH is a system, not a spray-bottle policy. Its parts:
The self-employed are inside the regime too: the owner-driver with a home workshop owes themselves the same thinking.
The pattern in practice is rarely exotic chemistry; it is routine exposure normalised over years. The aerosol used a hundred times a week with the extraction off because it rattles. The parts washer solvent topped up past its change date. Brake dust blown off with an airline, turning a settled hazard into a breathable cloud - exactly the “vacuum rather than brush” substitution HSE describes. Skin is the other quiet route: oils and solvents through ungloved hands, day after day, until dermatitis retires a fit mechanic. Each of these is a COSHH assessment finding waiting to be written down, and each has a control that is boring, cheap and already on the shelf.
Check the trade press and talk to the people doing the work when assessing - and ask other operators at trade meetings what they use; substitution ideas travel fast once someone else has made them work.
The brake cleaner that blinds, the dust that scars lungs over a decade, the solvent that dermatitises hands - none of it is exotic, and none of it is beyond a hierarchy that starts with “do we need this substance at all”.