Most UK workplaces use at least one substance that falls under the Control of Substances Hazardous to Health Regulations 2002, commonly known as COSHH — even businesses that would not think of themselves as handling "hazardous chemicals". Cleaning products, adhesives, welding fumes, wood dust, printer toner, and biological agents all fall within scope. COSHH compliance is not a niche manufacturing concern; it is one of the most widely applicable pieces of UK health and safety law, and one of the most commonly under-managed.
What COSHH actually requires
COSHH places a duty on employers to prevent or adequately control exposure to substances hazardous to health. In practice, that duty breaks down into a defined sequence: identify what hazardous substances are present, assess the risk they pose to workers, decide on and implement adequate controls, ensure those controls are used and maintained properly, monitor exposure where necessary, carry out appropriate health surveillance, and prepare for emergencies involving those substances. None of these steps are optional extras — COSHH assessment is a legal requirement wherever a hazardous substance is present, not a best-practice recommendation.
The regulation applies to substances that are explicitly labelled as hazardous, but also to dust at concentrations in air above defined limits, biological agents, and substances that have no defined workplace exposure limit but are known to cause harm. This is where many businesses miss scope — wood dust and silica dust from cutting materials are covered by COSHH just as much as a labelled solvent, and both require the same structured assessment.
Where COSHH assessments go wrong
The most common compliance gap is not the absence of a COSHH assessment altogether — most regulated workplaces have at least attempted one — but assessments that have not kept pace with what is actually being used on site. A COSHH assessment completed against the products purchased eighteen months ago is not valid if the supplier has changed formulation, a new cleaning product has been introduced by a different team, or a contractor has brought their own materials onto site without anyone cross-checking them against the existing assessment register.
Safety Data Sheets (SDS) are the starting point for any COSHH assessment, but relying on the SDS alone is a common and significant error. An SDS tells you about the substance in isolation; it does not tell you how it is actually used, at what concentration, in what ventilation conditions, by whom, for how long, or in combination with what other substances. Two sites using the identical product can have entirely different risk profiles depending on ventilation, task duration, and whether the work happens in a confined space. The assessment has to reflect actual conditions of use, not just the manufacturer's generic hazard data.
The hierarchy of control under COSHH
COSHH follows the same underlying logic as the general hierarchy of controls, applied specifically to hazardous substances:
- Eliminate the substance entirely if a hazard-free alternative achieves the same result.
- Substitute with a less hazardous substance or process where elimination is not possible.
- Engineering controls — local exhaust ventilation, enclosed processes, or automated handling to reduce exposure at source.
- Administrative controls — safe systems of work, exposure time limits, and signage.
- Personal protective equipment — respiratory protection, gloves, or protective clothing, used as the last line of defence, not the primary control.
A recurring finding in HSE enforcement activity is over-reliance on PPE as the default control, when engineering controls — extraction, containment, or process changes — would reduce exposure more reliably and do not depend on correct PPE use by every individual, every time. PPE compliance monitoring has a role, but it should sit alongside stronger upstream controls, not replace them.
Health surveillance and exposure monitoring
For certain substances and processes, COSHH requires more than control measures — it requires ongoing health surveillance to detect early signs of harm before they become serious. This applies particularly to substances associated with occupational asthma, dermatitis, or conditions with a long latency period, such as exposure to respirable crystalline silica or isocyanates. Where health surveillance is required, records must be kept for extended periods — often decades — because the health effects of some exposures only become apparent long after the exposure itself.
Exposure monitoring, where workplace exposure limits (WELs) apply, provides the evidence that controls are actually working, rather than assumed to be working. Without monitoring data, an employer cannot demonstrate that engineering controls are achieving adequate control, only that they exist.
Building a COSHH register that stays current
A COSHH assessment programme that stays accurate over time needs a structural answer to one recurring question: how does a new or changed substance actually get into the assessment register before it is used on site, rather than being discovered afterwards? Three practices make the biggest practical difference:
- A mandatory intake process — no new chemical product, cleaning agent, or material is brought onto site or used by any team, including contractors, without first being checked against the COSHH register and assessed if not already covered.
- Linking COSHH assessments to training and PPE records, so it is clear which workers have been trained on which substance, and whether the correct PPE has actually been issued and is in date.
- Scheduled review triggers, not just calendar-based reviews — a change in supplier, formulation, process, or quantity used should automatically prompt a reassessment rather than waiting for an annual review cycle.
Why COSHH management benefits from a connected system
COSHH assessment, exposure monitoring, health surveillance records, training records, and PPE issue are frequently managed as separate processes, often by different people, which is exactly how gaps appear — a worker using a substance they were never trained on, or PPE requirements that were updated on paper but never communicated to the people actually doing the work. Bringing these elements into one connected system is particularly valuable for manufacturing environments, where multiple hazardous substances, high substance turnover, and shift-based working make manual cross-checking increasingly unreliable as operations scale.
SiteChief's features include COSHH control tools that automatically extract hazard data from Safety Data Sheets and link exposure limits, PPE requirements, and storage rules directly to the substances actually in use — keeping the register current as conditions change, rather than reconstructing compliance retrospectively when an inspection is due.
Starting point for a compliance review
If your organisation's COSHH register has not been cross-checked against what is actually on site within the last twelve months, that mismatch is worth investigating before anything else. Walk the site, compare it against the register, and treat any substance not accounted for as a live compliance gap rather than a paperwork oversight — because under COSHH, that is precisely what it is.
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