Construction COSHH assessments: what contractors should check.

A construction COSHH assessment should identify the harmful substances supplied to or generated by the work, decide who might be exposed and how, then prevent exposure or reduce it to an adequately controlled level. It should translate product and process information into measures that workers can follow and supervisors can check.

The Control of Substances Hazardous to Health Regulations 2002 apply to many substances encountered in construction. Separate specific regulations cover asbestos and lead, so those materials should not be treated as routine COSHH entries.

A separate form is not the purpose in itself. What matters is a suitable and sufficient assessment completed before work that exposes employees to a hazardous substance begins. HSE says employers with five or more employees must record the assessment; writing down the findings is sensible for smaller businesses too.

Is a safety data sheet a COSHH assessment?

No. HSE says a safety data sheet (SDS) contains information that allows an employer to carry out a COSHH risk assessment, but the SDS is not itself the assessment. It describes the supplied product and its hazards. It does not know the contractor's method, quantity, work duration, ventilation, workforce, nearby trades or site conditions.

Use the current SDS to understand matters such as classification, ingredients, exposure controls, first aid, storage, accidental release and disposal. Then assess the actual use. For example, applying a small amount of sealant outdoors is not the same exposure scenario as using the same product repeatedly in a confined room.

Identify supplied and process-generated substances

Do not limit the substance register to containers carrying hazard pictograms. HSE specifically warns that work processes can produce harmful substances. Construction examples include:

• respirable crystalline silica created when cutting, chasing, grinding or drilling concrete, blocks, bricks, tiles and mortar;
• wood dust from sawing, routing and sanding;
• welding and hot-work fumes;
• cement, wet concrete, mortars and grouts that can affect the skin and eyes;
• solvents, paints, coatings, adhesives, sealants, cleaners and release agents;
• sprayed products, foams or coatings that may contain sensitising substances; and
• biological agents or contaminated material encountered during drainage, refurbishment or groundworks.

Start with the scope and sequence of work, not a generic chemical list. Walk through delivery, storage, decanting, mixing, application, cutting, cleaning, maintenance, spill response and disposal. Each stage can create a different exposure.

Assess how people could be exposed

For each substance or process, record the route, level and pattern of possible exposure. HSE tells employers to consider inhalation, skin contact or absorption, and accidental ingestion. The assessment should also consider:

• the amount and physical form—such as powder, paste, liquid, spray, dust, fume, vapour, mist or gas;
• how often the task occurs and how long each exposure may last;
• whether the work is outdoors, indoors, enclosed or poorly ventilated;
• the method, tools, temperature and energy used, because these affect the release;
• employees doing the task and others nearby, including other trades, maintenance workers, cleaners, visitors and the public;
• people who may be particularly susceptible where that is relevant to the substance or work; and
• any workplace exposure limit and whether monitoring or specialist advice is needed to demonstrate control.

The assessment should distinguish a hazard from the likelihood of exposure in the planned conditions. Copying the SDS hazard statements without assessing the task leaves the critical question unanswered: what will prevent harm during this job?

Use the control hierarchy before relying on PPE

The first question is whether the substance or process can be eliminated. If it cannot, consider a safer product, form or method. Examples might include pre-cutting material in a controlled facility, using a lower-dust product, wet cutting instead of uncontrolled dry cutting, or selecting a brush or roller method instead of spraying where technically suitable.

Where exposure cannot be prevented, the assessment should set out adequate controls in a reliable order:

1. change the product, process or task to reduce the amount released;
2. contain or enclose the source where practicable;
3. use properly designed extraction, ventilation, water suppression or on-tool controls;
4. restrict access, minimise duration and coordinate the work with other activities;
5. provide suitable storage, handling, cleaning and waste arrangements; and
6. use suitable personal protective equipment as part of the remaining control package.

HSE says PPE should not be the automatic first choice because it is less reliable than other controls. Where respiratory protective equipment is required, the assessment should specify a suitable type for the hazard and task. Tight-fitting facepieces require a fit test for the individual wearer and depend on clean-shaven contact where the seal sits.

Cover the full site arrangement, not just the person using the product

A usable assessment should answer the practical questions that arise before the task starts:

• Where will the material be received and stored, and which incompatible products must be separated?
• Who may decant, mix or use it, and what equipment and supervision are required?
• How will the work area be ventilated, segregated and signed?
• How will workers clean tools, surfaces, workwear and themselves without spreading contamination?
• What spill kit, eyewash, first aid and emergency actions are needed, and who knows how to use them?
• How will empty containers, contaminated absorbents and other waste be controlled and removed?
• Does the substance create a fire, environmental or transport risk that must also be managed under other arrangements?

Dry sweeping can redistribute hazardous dust. HSE advises using dust-free cleaning methods such as suitable vacuum equipment. The assessment should name the method and equipment rather than say only “maintain good housekeeping”.

Coordinate the COSHH assessment with the RAMS and method statement, the Construction Phase Plan, permits and manufacturer instructions. These documents should agree on the task sequence and controls rather than create competing versions.

Brief the findings and verify that controls work

Workers need information and training that connects the assessment to the task. Before work, the briefing should cover the health effects, exposure routes, controls, correct use and limitations of equipment, hygiene, symptoms to report and emergency action. Record who was briefed and provide the assessment in a form they can understand.

Supervisors should check implementation at the workface. That may include confirming that the correct product and revision are present, extraction or suppression is operating, exclusion measures remain effective, PPE is worn correctly and storage and waste controls are being followed.

Some substances and exposure patterns may require exposure monitoring or health surveillance. The need is driven by the regulations, risk and substance—not by a generic tick box. Where it applies, arrange it through competent occupational hygiene or occupational health support and explain the relevant process to workers.

When should a construction COSHH assessment be reviewed?

Keep the assessment current throughout the work. Review it when:

• the product, supplier, concentration or safety data changes;
• the method, tools, quantity, frequency or duration changes;
• work moves to a different location or ventilation condition;
• new workers or nearby activities change who may be exposed;
• controls, extraction, suppression or PPE may no longer be effective;
• monitoring, health surveillance or inspection identifies a concern; or
• there is a spill, incident, near miss, symptom report or worker concern.

A review date is useful, but it should not delay a review triggered by a real change. Update the controlled document, remove obsolete copies and rebrief affected people.

A contractor's pre-start COSHH checklist

Before accepting an assessment for site use, check that it:

• matches the exact product or process and current information;
• describes the real task, location, amount, frequency and duration;
• covers substances created by the work as well as supplied products;
• identifies everyone who could be exposed and the relevant routes;
• uses elimination, substitution and engineering controls before defaulting to PPE;
• specifies storage, cleaning, spill, first-aid, emergency and waste arrangements;
• states any monitoring, health surveillance, training or supervision required;
• agrees with the RAMS, site rules and equipment actually available; and
• has clear ownership, briefing, issue and review arrangements.

A generic template can provide headings, but it is not automatically suitable, approved or site-ready. It must be assessed and adapted by a competent person for the project, task and workforce, then briefed and implemented.

IMERI H&S Partners provides construction COSHH assessment support for contractors and project teams in Watford, Hertfordshire, London and across the South East. The appropriate scope depends on the materials, processes, exposure potential and information already available.