Control measures are everything you put in place to prevent or adequately control exposure, and they come in an order that matters more than any individual item on the list. Firms that start at the bottom of the hierarchy, with gloves and a mask, spend more and protect less than firms that start at the top. This page sets out the order, says which substances the duty applies to, and gives examples of what each level looks like in an ordinary workplace rather than in a textbook.
The hierarchy, top to bottom, with what each looks like
Eliminate: stop using the substance, or stop doing the task that needs it. Substitute: a less hazardous substance, or a less hazardous form of the same one, powder to pellet or spray to brush. Engineering control: enclose the process, or extract at source with local exhaust ventilation that is examined and tested. Ways of working: fewer people exposed, for less time, with better housekeeping and no eating in the area. Protection and information: respiratory protective equipment, gloves, training and labelling. Each level down is cheaper to buy and more expensive to rely on.
Which substances the duty covers
Substances hazardous to health used in or arising from work: purchased chemicals, and equally the dusts, fumes, mists, vapours, gases and biological agents a process creates. Wood dust, silica dust from cutting stone, welding fume, solder fume, flour dust and oil mist all count and none of them arrives with a label. Asbestos, lead and radioactive materials are outside COSHH and have their own regulations, which is a genuine exclusion rather than a gap.
Why personal protective equipment is the last resort and not the first
Protective equipment works only when it is the right specification, fitted to the individual, worn every time, maintained, and stored somewhere it does not get contaminated. Every one of those is a way for the control to fail silently, and none of them applies to a fume cupboard. That is not an argument against protective equipment, it is an argument for treating it as the layer that catches what the earlier layers missed rather than as the plan.
Controls have to be maintained, examined and tested, or they are decoration
Engineering controls degrade. Extraction loses performance as ducts foul and filters load, and a system that was adequate at commissioning may not be adequate now. The duty includes keeping controls in efficient working order and, for some engineering controls, examining and testing them on a defined cycle. The free COSHH assessment worksheet on this site treats the substances needing this level of control as their own tier, because they are the ones that carry ongoing cost.
Questions people ask about coshh control measures
What substances does COSHH include?
Chemicals you buy and hazardous substances your work creates: dusts, fumes, mists, vapours, gases and biological agents. It does not cover asbestos, lead or radioactive substances, each of which is regulated separately, and it treats some hazards by reference to airborne concentration rather than to the container.
Are nanomaterials and technology covered by COSHH?
Where an engineered nanomaterial is a substance hazardous to health used in or arising from work, the same duties apply. The practical difficulty is thinner hazard data for some nano forms, which argues for more precautionary control rather than for treating missing information as an absence of risk.
Can you give COSHH examples of good control?
Swapping a solvent-based cleaner for a water-based one is substitution. Putting a lid on a degreasing tank is enclosure. Moving a cutting operation outdoors and wetting the blade is an engineering and working-method change together. Issuing better gloves is the last of the five, and it is where most firms start.