COSHH for Contractors: Share Risks Before Work Starts

COSHH for contractors starts before they arrive on site. The host needs to explain the hazardous substances and controls already present; the contractor needs to explain what its work may introduce or generate. Both sides then check the actual task, location and interface with other work so that a generic assessment does not hide an exposure route.

What information should each side share?

The host should describe substances and processes in the area, relevant local restrictions, ventilation, storage arrangements and emergency procedures. The contractor should identify products it intends to use and substances its work could create, such as dust or fume. A product list should include the current safety data sheets (SDS) where relevant, but HSE says an SDS is not a risk assessment.

HSE's COSHH assessment guidance explicitly tells employers to include maintenance workers and contractors among those who could be exposed. It also says contractors need to know workplace risks and controls, while the host needs to know whether contractors bring hazardous substances onto the premises and how they will prevent harm to the host's workers. The exchange must therefore run both ways.

Use an agreed pre-work record: task, location, dates, products, foreseeable releases, people nearby, controls, waste route, emergency contacts and who approves changes. If the contractor will work outside normal hours, check that the controls and contacts still exist at that time. A ventilation system available during production may be switched off during a shutdown.

Why are generic contractor COSHH sheets often insufficient?

A generic sheet can identify a product and typical controls, but it cannot describe every site. One solvent task may be in a well controlled workshop; another may be in a small plant room with limited access and adjacent hot work. One drilling method may produce dust close to occupied offices, while another is isolated. The same paper form does not make these exposures equivalent.

Walk through the intended method with a supervisor who knows the site. Ask where containers will be opened, how much will be used, what extraction or containment is available and who else might pass through. Verify that the proposed personal protective equipment is available and suitable for the specific product and task. If a control relies on a host system, agree who will check that it is operating before work begins.

The assessment should also consider the contractor's clean-up, waste and decontamination. Exposure can occur after the main task when a contaminated tool is packed away or waste is carried through a corridor. Define where materials can be stored and whether the contractor may leave containers on site overnight.

How should controls be coordinated on site?

Name a host contact and contractor lead. They should agree the work boundary, access rules, permit or authorisation where required, and a simple stop-work route if conditions differ from the plan. HSE's control measures guidance treats methods of working, supervision, training and emergency procedures as part of exposure control. A control written into an assessment but not coordinated at the workface is unlikely to be reliable.

Brief people in adjacent areas where their behaviour matters. They may need to avoid an area, keep a door closed or report a ventilation alarm. Do not rely on the contractor's PPE to protect other people. If dust, fume or vapour could migrate, first consider release prevention, enclosure and extraction, then confirm the boundary remains effective while work proceeds.

Check that the actual products and equipment match the pre-work submission. Substitution on the day may change hazards or controls. A new product or method needs review before use, even if the contractor regards it as a minor purchasing change. Record the decision and communicate it to the people affected.

What should be checked during and after the job?

During work, look for the exposure conditions the assessment predicted: releases, ventilation operation, containment, housekeeping and people entering the area. Workers should be able to explain the control they are using and what they would do if it fails. If the real conditions are different, pause and revise the plan rather than trying to make the paperwork fit afterwards.

At handover, confirm that substances, waste and contaminated equipment have been removed or stored as agreed. Check whether any residue, temporary control or follow-up monitoring remains. Record incidents and near misses, including exposures to host staff. Review the arrangements before the next similar job so the learning is not lost in a closed permit.

Linking product, location and assessment records helps both sides find the current information. Safe Foundry's features describe a chemical register and document workflow; the help centre can support local setup. The practical standard is simple: everyone affected should know what the work can release, where the boundary is and who can stop it.

What would a pre-start conversation cover?

Suppose a contractor will repair a pump in a chemical store. The host describes the products and residues in the area, how the pump is isolated and whether extraction or washing facilities will be available. The contractor explains its cleaning agent, tools, expected waste and any dust or vapour the repair may generate. Together they identify who might enter the store, where materials can be placed and which change requires a pause. This conversation should happen before equipment is opened, not after the contractor has already arrived with an unlisted product.

A simple pre-start checklist can ask: Are the product identities and SDS versions confirmed? Is the task area as described? Are the controls present and working? Who will warn neighbouring workers? What if a leak or unexpected residue is found? Who approves a substitute product or altered method? The answers become a brief work instruction that both leads can check during the job.

How should changes be managed during the job?

Contractor work often reveals unknown conditions. A damaged line may contain residue, or the planned cleaning method may not remove it. The right control is a clear pause point: isolate the task, describe the new condition and get competent review of exposure and controls. A supervisor should not ask the contractor to improvise because the job is nearly complete. The host may need to notify other teams if the boundary or schedule changes.

When work resumes, note the revised product, method, controls and people informed. At handover, compare the final condition with what was authorised. If contaminated parts, temporary barriers or waste remain, assign an owner and date for removal. This prevents a contractor's short visit from leaving a long-term exposure route for cleaners, stores staff or the next maintenance team.

What should the final handover say?

The host and contractor should confirm whether the work area is safe for normal use, what products and waste remain, whether temporary controls are still needed and who will complete outstanding actions. If a line or vessel was opened, record whether it was cleaned and closed as planned. Give adjacent teams the information they need before barriers are removed. A clear handover prevents exposure after the contractor has left, when the people who understood the work may no longer be present.

Keep the contractor's final method and product list with the job record. If the task is repeated, that evidence can improve the next pre-start review, while still requiring a fresh check of site conditions.