COSHH Assessment for Construction Explained

Construction sites generate a wider and more concentrated range of hazardous substances than almost any other workplace. Cutting concrete, mixing cement, spraying foam insulation, running diesel plant in confined spaces — each creates exposure that can cause serious, irreversible harm. A COSHH assessment is the legal mechanism for identifying that harm and putting controls in place before anyone is exposed.

This guide explains what a COSHH assessment is, what the law requires, how to complete one for a real construction task, and exactly how it fits inside the RAMS documents your principal contractor or client will review.

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What is a COSHH Assessment and Why Does Construction Need a Specific Approach?

A COSHH assessment is a structured, documented evaluation of the health risks created by a hazardous substance during a specific task, and a record of the controls chosen to reduce exposure to an acceptable level.

Generic COSHH guidance covers laboratories, workshops and cleaning operations. Construction demands a different emphasis because:

• Substance generation is process-driven. On a construction site you do not only import substances in labelled containers — you create them. Cutting, grinding, abrading and burning generates respirable dusts and fumes that do not come with a manufacturer's safety data sheet (SDS).
• Exposure is intermittent but intense. A groundworker cutting a concrete kerb for 20 minutes can receive a significant proportion of a daily exposure dose in one burst.
• The workforce is mobile. Workers move between tasks, trades and sites. Cumulative exposure across a career is the occupational disease risk, not a single shift.
• Multiple substances co-exist. On a live site, RCS, wood dust, diesel exhaust, cement and solvent vapour may all be present simultaneously in the same work area.

These factors mean that a construction COSHH assessment must be task-specific, substance-specific, and linked to the method of work — not a generic tick-box exercise.

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The Legal Duty: What the Control of Substances Hazardous to Health Regulations 2002 (SI 2002/2677) Actually Requires

The Control of Substances Hazardous to Health Regulations 2002 (SI 2002/2677) is the primary statutory instrument placing duties on employers to assess and control exposure to hazardous substances at work. (Control of Substances Hazardous to Health Regulations 2002 (SI 2002/2677))

The Regulations set out a chain of duties, each with its own regulation number:

• Regulation 6 — Assessment of the risk to health created by work involving substances hazardous to health. Employers must assess the risk before the work is carried out and identify the measures needed to comply with the Regulations.
• Regulation 7 — Prevention or control of exposure. Once the assessment identifies a hazardous substance, the employer must prevent exposure or, where that is not reasonably practicable, adequately control it.
• Regulation 8 — Use of control measures. Employers must ensure that control measures are properly used, and employees must make full and proper use of any control provided.
• Regulation 9 — Maintenance, examination and testing of control measures. Control measures — including local exhaust ventilation (LEV) — must be maintained in an efficient state, and where appropriate examined and tested at suitable intervals.
• Regulation 10 — Monitoring exposure at the workplace where monitoring is necessary to ensure adequate control or to protect health.
• Regulation 11 — Health surveillance where there is a reasonable likelihood that a disease or adverse health effect will result and surveillance is appropriate.
• Regulation 12 — Information, instruction and training for persons who may be exposed.

The assessment duty in Regulation 6 is not satisfied by a generic document. It must be suitable and sufficient for the specific substances, tasks and workers involved. On a construction site that means a separate — or clearly distinct — assessment for each substance group that presents a different health risk profile.

Note on asbestos: The Control of Asbestos Regulations 2012 operates as a separate regulatory regime for asbestos work. Do not assume COSHH 2002 covers licensed asbestos removal — it does not. Where asbestos-containing materials may be present, a separate asbestos management assessment is required. COSHH assessments should carry a cross-reference flag to this.

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Construction Substances That Trigger a COSHH Assessment: The Definitive Site List

The following substance groups appear on the vast majority of UK construction sites and require individual COSHH assessments:

Substance / Agent	Source on site	Primary health risk
Respirable crystalline silica (RCS)	Cutting/grinding concrete, stone, block, mortar	Silicosis, lung cancer, COPD
Wood dust	Carpentry, formwork, engineered timber cutting	Nasal cancer, asthma, dermatitis
Cement (wet)	Mixing, laying, rendering, block-laying	Skin sensitisation, chrome VI dermatitis
Diesel exhaust particulates (DEP)	Plant, generators, welfare units in confined or poorly ventilated spaces	Lung cancer, cardiovascular disease
Isocyanates	Spray foam insulation, two-part polyurethane coatings	Occupational asthma (sensitiser — irreversible)
Solvents (VOCs)	Adhesives, primers, waterproofing membranes, paints	CNS effects, skin/eye irritation
Epoxy resins	Structural repairs, bonding agents, floor coatings	Skin sensitisation, occupational asthma
Mould / biological agents	Demolition of existing structures, water-damaged materials	Respiratory disease, Farmer's lung type conditions
Asbestos — cross-reference only	Existing structure disturbance	Mesothelioma, asbestosis — Control of Asbestos Regulations 2012 applies, not COSHH alone

Workplace Exposure Limits (WELs) for most of these substances are set out in HSE's EH40 Workplace Exposure Limits document. Always consult the current edition of EH40 for the applicable 8-hour time-weighted average (TWA) and short-term exposure limit (STEL) values — do not rely on figures reproduced in secondary guidance, which may be out of date.

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Step-by-Step: How to Complete a COSHH Assessment for a Construction Task

Step 1 — Identify the substance(s) List every substance involved in the task: those brought to site (from SDS), those generated by the process (dusts, fumes, vapours), and those present in existing structures (legacy materials, contaminated ground).

Step 2 — Determine the hazardous properties Using the SDS, EH40, and HSE construction guidance, identify: health hazard classification, primary exposure route (inhalation, skin, ingestion), acute versus chronic effects, and whether the substance is a sensitiser, carcinogen, or mutagen.

Step 3 — Evaluate who is at risk and how Name the job roles exposed. Estimate the duration, frequency and intensity of exposure. Consider bystanders and adjacent trades — not just the operative doing the task.

Step 4 — Assess the level of risk (severity × likelihood) Score severity (consequence of uncontrolled exposure: 1–5) and likelihood (probability of exposure occurring at that level: 1–5). Multiply to produce a risk rating. This step drives the urgency and level of control required.

Step 5 — Apply the control hierarchy (Regulation 7) Work down the hierarchy; do not jump to RPE:

1. Elimination — can the task be redesigned to avoid the substance entirely?
2. Substitution — can a less hazardous substance or method be used (e.g. pre-cut components instead of on-site cutting)?
3. Engineering controls — on-tool dust extraction (H-class vacuum), local exhaust ventilation (LEV), wet suppression, enclosure.
4. Administrative controls — job rotation to limit exposure duration, segregation of dusty tasks, worker information and training.
5. RPE — respiratory protective equipment as the last resort, selected to achieve adequate protection factor for the substance, worn only after all higher-level controls are in place.

Step 6 — Identify monitoring and health surveillance needs Where engineering controls alone may not reliably keep exposure below the WEL, air monitoring should be specified. Certain substances (e.g. isocyanates) require health surveillance under Regulation 11.

Step 7 — Record the assessment Document all of the above in a structured format. The assessment must be accessible to workers, supervisors and the PC.

Step 8 — Set a review date and review triggers See the review log template in the asset section below.

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Worked Example: COSHH Assessment for Concrete Cutting and RCS Exposure

Unique Asset — Worked Example This worked example is specific to construction sites. Review and adapt it to your own site conditions, task details and contractor before use. It is not a substitute for a site-specific assessment completed by a competent person.

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COSHH ASSESSMENT — WORKED EXAMPLE

Field	Detail
Assessment reference	COSHH-001
Date of assessment	[Insert date]
Assessed by	[Name, competency]
Review date	12 months or earlier if trigger event occurs
Task	Concrete floor cutting using a floor saw (diamond blade)
Location	Ground floor slab, new-build commercial unit — partially enclosed
Substance	Respirable crystalline silica (RCS) generated from cutting concrete
Substance source	Process-generated — no SDS; refer to HSE EH40 for WEL
Exposure route	Inhalation (primary); incidental ingestion (secondary)
Persons at risk	Floor saw operator (direct); groundworker clearing debris; adjacent carpenter (10 m bystander)
Duration of exposure	Cutting: approx. 3 hours cumulative per shift
Severity score (1–5)	5 — Silicosis is irreversible; RCS classified as a Group 1 carcinogen by IARC
Likelihood without controls (1–5)	5 — Dry cutting of concrete produces very high dust concentrations
Uncontrolled risk rating	25 — Unacceptable

Control hierarchy applied:

Control level	Measure specified
Elimination	Not reasonably practicable — cut required to achieve drainage fall
Substitution	Pre-cut off-site sections specified for all straight runs >1 m; on-site cutting minimised
Engineering — wet suppression	Continuous water feed to blade at point of cut; blade guard with water feed attachment fitted
Engineering — on-tool extraction	H-class vacuum extraction unit connected to blade shroud for residual dry swarf
Engineering — enclosure / segregation	Temporary hoarding erected around 4 m exclusion zone; signage posted
Administrative	Daily tool-box talk covering dust controls; buddy check on controls before start; job rotation if cutting >2 hours per operative
RPE (last resort)	FFP3 disposable half-mask (or P3 reusable) fitted and face-fit tested for all persons within exclusion zone. RPE worn in addition to, not instead of, engineering controls

Field	Detail
Residual risk rating	6 — Acceptable with controls in place
Monitoring required?	Air monitoring recommended if wet suppression system fails or is impractical — engage hygienist
Health surveillance required?	Yes — ongoing lung function monitoring for operatives with >1 year cumulative RCS exposure; record in health surveillance file
Review triggers	See trigger-event log below
RAMS cross-reference	Method Statement ref MS-004, Risk Assessment ref RA-003

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The Control Hierarchy — Applying It on Site, Not Just on Paper

The hierarchy under Regulation 7 is a priority order, not a menu of equivalent options. The practical failure mode on construction sites is reaching for RPE as the primary response because it is cheap and immediate, while skipping engineering controls that are more effective but require planning.

Signs that the hierarchy has been inverted on your site:

• Workers wearing FFP3 masks but no wet suppression or extraction in place during concrete cutting.
• "PPE as required" listed as the only COSHH control in the method statement.
• No face-fit test records despite RPE being specified.

LEV (local exhaust ventilation) is an engineering control under Regulation 9 — it must be kept in an efficient state and examined and tested as required by the Regulations. For on-tool extraction this means checking that the H-class vacuum filter is intact, the shroud seal is unbroken, and airflow is adequate at the start of every shift, not just at first use.

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How a COSHH Assessment Fits Inside Your RAMS Document

RAMS (Risk Assessment and Method Statement) is the combined document package that operatives, supervisors and principal contractors use to manage safe working. A COSHH assessment is a distinct statutory document but it must be consistent with — and referenced from — the RAMS.

COSHH Assessment vs RAMS: Shared and Unique Fields

Data field	COSHH assessment	Risk assessment (RAMS)	Method statement (RAMS)
Task description	✅ Required	✅ Required	✅ Required
Substance identification	✅ Primary field	Referenced from COSHH	Referenced from COSHH
Exposure route	✅ Primary field	Summarised	—
Health hazard classification	✅ Primary field	Referenced	—
WEL / EH40 reference	✅ Required	Optional cross-ref	—
Severity × likelihood scoring	✅ Required	✅ Required	—
Control hierarchy (all levels)	✅ Required in full	✅ Required	Described as work sequence
RPE type and face-fit test ref	✅ Required	✅ Required	✅ Referenced
Monitoring / health surveillance	✅ Required	Referenced	—
Safe working procedure / sequence	—	—	✅ Primary field
Emergency arrangements	Referenced	Referenced	✅ Primary field
Review date / triggers	✅ Required	✅ Required	On revision
Document reference number	✅ Cross-ref to RAMS	✅ Cross-ref to COSHH	✅ Cross-ref to COSHH

Practical rule: Write the COSHH assessment first. Extract the substance, exposure route, hazard classification and control hierarchy — then populate the corresponding RAMS fields by reference. This eliminates contradictions between documents (a common reason for PC rejection) and avoids duplicating information that then gets maintained inconsistently.

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Who Can Carry Out a COSHH Assessment on a Construction Site?

The Regulations place the duty on the employer. The employer may delegate the practical task of completing the assessment, but they cannot delegate the legal responsibility.

The person carrying out the assessment must be competent — meaning they have sufficient knowledge, training and experience to:

• Identify the substances present (including process-generated substances that have no SDS).
• Understand the health effects, exposure routes and relevant WELs for construction substances.
• Apply the control hierarchy correctly and identify whether engineering controls are adequate.
• Recognise when specialist input (occupational hygienist, health surveillance provider) is needed.

On most construction sites this will be a competent SHEQ professional, a qualified site manager with relevant training, or a specialist subcontractor with documented competence for their trade. For complex or high-risk substances (isocyanates, novel chemicals, potential carcinogens), commission an occupational hygienist.

Competence is not conferred by membership of an industry accreditation scheme alone. Schemes such as CHAS and SSIP assess management systems — they are not a legal standard for COSHH assessment competency and should not be cited as such.

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Review, Record-Keeping and Audit: What You Must Do After the Assessment

When must a COSHH assessment be reviewed?

An assessment is not a one-off document. It must remain valid for the work it covers. Review is required when:

Trigger-Event Review Log Template

#	Date of change	Nature of trigger	Details	Action taken	Reviewed by	Sign-off date
1		New substance introduced
2		New task / change to work method
3		WEL exceedance identified (monitoring result)
4		Incident, near-miss or ill-health report
5		Change in workforce / new trades on site
6		Engineering control failure (e.g. LEV breakdown)
7		Manufacturer / SDS update for a substance in scope
8		12-month periodic review cycle reached

Complete a new row for every review event. Attach the updated assessment as a new version; retain the superseded version.

Record-keeping

The assessment must be recorded in writing where it is required under the Regulations. Retain all versions of the assessment, the trigger-event log, monitoring records, and health surveillance records. For specific retention periods, consult current HSE guidance — do not rely on figures quoted in secondary sources, which may not reflect current requirements.

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Eight-Point COSHH Assessment Completion Checklist for Construction

Use this checklist before submitting a COSHH assessment to your principal contractor or filing it in your safety management system.

#	Checkpoint	✅ / ❌	Notes
1	Substance(s) identified — including process-generated dusts and fumes, not only labelled products. SDS obtained for all packaged substances.
2	Exposure routes stated — inhalation, skin absorption, ingestion identified separately for each substance.
3	All persons at risk named by role — operator, bystanders, adjacent trades. Vulnerable workers (young persons, those under health surveillance) specifically considered.
4	WEL cross-referenced — current edition of HSE EH40 consulted for applicable 8-hour TWA and STEL. Isocyanates, RCS, wood dust, cement dust checked specifically.
5	Control hierarchy applied in sequence — elimination and substitution considered before engineering controls; RPE specified only as last resort with face-fit test reference included.
6	Monitoring / health surveillance requirement stated — decision to monitor or not monitor is documented with reasoning; health surveillance need assessed for sensitisers (isocyanates, chrome VI, epoxy resins) and dust-generating tasks.
7	Asbestos cross-reference flag — if existing structure is disturbed, confirmation that a separate asbestos assessment under the Control of Asbestos Regulations 2012 has been completed or is not required (with basis stated).
8	RAMS cross-reference confirmed — assessment reference number appears in the corresponding risk assessment and method statement; no contradictions between documents on substance identification, controls, or RPE specification.

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Frequently Asked Questions

What is a COSHH assessment and why is it legally required on construction sites? A COSHH assessment is a documented evaluation of the health risks from hazardous substances used or generated during work, and a record of the controls applied. It is required by the Control of Substances Hazardous to Health Regulations 2002 (SI 2002/2677), which place a duty on employers to assess and control exposure before work involving hazardous substances begins.

Which substances on a construction site require a COSHH assessment? Any substance that is hazardous to health requires an assessment. On construction sites this routinely includes RCS (from concrete, stone and masonry cutting), wood dust, wet cement, diesel exhaust particulates, isocyanates, solvents, epoxy resins and mould. Asbestos requires a separate assessment regime under the Control of Asbestos Regulations 2012.

What is the difference between a COSHH assessment and a general risk assessment? A general risk assessment covers all hazards associated with a task (mechanical, physical, environmental, health). A COSHH assessment specifically addresses substances hazardous to health — their identification, exposure routes, WEL comparison, and a control hierarchy focused on health outcomes. Both documents are required; the COSHH assessment provides the substance-specific detail that a risk assessment summary cannot adequately capture.

Who is competent to carry out a COSHH assessment on a construction site? The employer holds the duty, but a competent person — with knowledge of construction substances, exposure routes, WELs and control methods — carries out the assessment in practice. For high-risk or novel substances, commission an occupational hygienist.

How often must a COSHH assessment be reviewed? At a minimum, periodically (most organisations use a 12-month cycle as standard practice), and immediately upon any trigger event: new substance, new task, WEL exceedance, incident, ill-health report, SDS change, or engineering control failure. Use the trigger-event log above to document every review.

What records must be kept and for how long? The written assessment, all superseded versions, monitoring records and health surveillance records must be retained. Consult current HSE guidance for the specific retention periods applicable to your substances and sector.

How does a COSHH assessment interact with a RAMS document? The COSHH assessment is the primary document for substance hazard detail. The RAMS draws from it — the risk assessment summarises the controls; the method statement describes how they are implemented in the work sequence. Write the COSHH assessment first and cross-reference both documents to eliminate contradictions. See the mapping table above.

What does a Legionella COSHH assessment for a construction welfare unit need to cover? As a minimum, identify all water storage, distribution and outlet points, assess where water may stagnate or sit at temperatures that allow bacterial growth, and specify control measures — typically flushing regimes, temperature checks, and, where appropriate, disinfection. ACoP L8 requires dutyholders to appoint a responsible person, prepare a written scheme to prevent or control the risk, and keep records of precautions taken. Treat this as a live document: welfare units reconfigured or decommissioned mid-project present a changing risk profile that should trigger a reassessment.

Is lead covered by COSHH, and what do I need to know when stripping old paint or carrying out demolition? Lead is explicitly excluded from the scope of the Control of Substances Hazardous to Health Regulations 2002. Work involving lead — including stripping lead-based paint, cutting lead-flashed structures, or demolishing buildings where lead is present — is governed by its own dedicated regulatory regime with an associated Approved Code of Practice. Your COSHH assessment should carry a cross-reference flag to this, in the same way the page already flags asbestos, to ensure assessors do not inadvertently treat a lead task as a routine COSHH matter.

Where should lead appear in a construction RAMS document set? Because lead falls outside COSHH, it requires a standalone assessment referencing its own regulatory framework rather than a COSHH assessment form. In practice, the method statement should identify activities with lead exposure potential — paint removal by heat gun or abrasive methods, demolition of pre-1970s structures, or working with heritage leadwork — and direct the reader to the separate lead assessment. Cross-referencing both documents within the RAMS pack is good practice and helps a principal contractor verify that the correct regime has been applied.

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How Ramsdocs Helps Construction Teams Produce and Store COSHH Assessments

Product functionality — not a legal obligation

Ramsdocs provides construction-specific COSHH assessment templates pre-structured around the Regulation 6 duty, with substance-group prompts for RCS, wood dust, cement, DEP, isocyanates, solvents and epoxy resins built in. The platform:

• Guides assessors through each step of the control hierarchy in sequence, preventing RPE-first shortcuts.
• Cross-links COSHH assessments to the corresponding RAMS document within the same project, flagging field contradictions before submission.
• Stores the trigger-event review log against each assessment and sends review reminders at user-defined intervals.
• Maintains a version history of all assessments, supporting audit and record-keeping obligations.

COSHH assessments produced using Ramsdocs are designed to be PC review-ready and to reduce RAMS rework — but every assessment must be reviewed and adapted to your specific site, task and contractor by a competent person before use.

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Disclaimer: The content on this page is intended as educational guidance on COSHH assessment practice for construction sites. It does not constitute legal advice. The worked example and templates provided must be reviewed, completed and adapted to your specific site conditions, substances, tasks and workforce by a competent person before use. Ramsdocs does not guarantee that any document produced will be accepted by a principal contractor, the HSE, or any other body. Always consult current HSE guidance and, where required, a qualified occupational hygienist or health and safety professional.