COSHH and LEV: Your Legal Obligations as an Employer

If you operate local exhaust ventilation in the UK, the Control of Substances Hazardous to Health Regulations 2002 — COSHH — is the law that governs how you manage it. Not the only law, but the one that matters most for day-to-day LEV compliance.

COSHH isn't a vague set of principles. It places specific, enforceable duties on employers. Three regulations in particular create the framework around LEV systems. Here's what each one requires and how they connect.

What COSHH Is

COSHH is a set of statutory regulations made under the Health and Safety at Work etc Act 1974. It applies to every employer in the UK whose workers are or may be exposed to hazardous substances — dusts, fumes, vapours, mists, gases, biological agents, and any substance with a workplace exposure limit.

That covers most workplaces. If you run a woodworking shop, a bakery, a welding fabrication unit, a dental practice, a nail salon, a laboratory, a spray booth, or a commercial kitchen, COSHH applies to you. The HSE's COSHH guidance provides the full scope.

COSHH creates duties at every stage: assess the risk, control exposure, maintain your controls, test and examine them, monitor the workplace, carry out health surveillance where required, and train your people. LEV sits at the heart of this because it's the most common engineering control used to meet the duty to adequately control exposure.

Regulation 7 — Adequate Control of Exposure

Regulation 7 is where it starts. It requires every employer to ensure that exposure to hazardous substances is either prevented or, where prevention isn't reasonably practicable, adequately controlled.

COSHH sets out a hierarchy of control measures:

1. Eliminate the substance or the process that generates it
2. Substitute a less hazardous alternative
3. Enclose the process to contain the substance
4. Engineering controls — LEV sits here
5. Administrative controls and PPE — last resort only

LEV enters the picture at step 4. If you can't eliminate the hazard, substitute it, or fully enclose the process, you need engineering controls to capture the substance at source. That's what LEV does.

Critically, PPE (dust masks, respirators) should not be your primary control if LEV is reasonably practicable. An employer who hands out face masks instead of installing extraction where extraction would work is not meeting Regulation 7. The HSE's position on this is clear — PPE is supplementary, not a substitute for proper engineering controls.

What "adequate control" means

For substances with a workplace exposure limit (WEL), adequate control means keeping exposure below that limit. For carcinogens, mutagens, and substances causing occupational asthma, the duty is stricter: you must reduce exposure as far as is reasonably practicable, even if exposure is already below the WEL.

Your COSHH assessment (required under Regulation 6) is what determines which substances are present, what the exposure risk is, and which control measures are needed. If the assessment identifies LEV as necessary, you must install and operate it. There's no discretion once the assessment has been done properly.

Regulation 9 — Examination, Testing, and Maintenance

This is the regulation that most directly affects LEV management. Regulation 9 creates four duties:

1. Maintain LEV in efficient working order, efficient working condition, and good repair.

This is a continuous obligation. It means routine maintenance — replacing filters, repairing damaged ductwork, adjusting hoods, replacing worn belts — not just waiting for the annual examiner. A system that's technically "working" but performing below its design specification doesn't meet this duty.

2. Thorough examination and test (TExT) at intervals not exceeding 14 months.

Every LEV system provided as a COSHH control measure must be formally examined and tested by a competent person at least once in every 14-month period. This involves measured performance testing against the system's design specification, a physical inspection of all components, and a written report. It's not a service call — it's an independent assessment of whether the system is doing its job.

3. Keep records for a minimum of 5 years.

Every TExT report must be retained for at least 5 years and be available for HSE inspectors on request. HSG258 also recommends keeping records of user checks and routine maintenance.

4. Ensure LEV is properly used.

Workers must actually use the system when carrying out work that generates airborne contaminants. A dust extraction system that nobody switches on doesn't meet the legal requirement, regardless of how well it's maintained.

Regulation 12 — Health Surveillance

Regulation 12 requires health surveillance for employees exposed to certain hazardous substances, even when controls like LEV are in place. This applies when your COSHH assessment identifies exposure to substances known to cause identifiable diseases or adverse health effects, and there's a valid technique for detecting early signs.

For LEV operators, health surveillance is most commonly relevant when workers are exposed to:

• Wood dust — associated with nasal cancer and occupational asthma
• Welding fume — linked to lung cancer and occupational asthma (HSE updated its enforcement position on welding fume in 2019, following evidence that all welding fume — not just stainless steel — poses a carcinogenic risk)
• Isocyanates — found in spray paints and foam production, a leading cause of occupational asthma
• Flour dust — causes baker's asthma
• Silica dust — causes silicosis

Health surveillance might include lung function tests (spirometry), skin checks, or symptom questionnaires, depending on the substance. The results can also tell you something about your LEV's effectiveness. If workers develop symptoms despite LEV being in place, the system may not be controlling exposure adequately — which circles back to Regulation 7.

How COSHH Assessments Connect to LEV

The COSHH assessment is the foundation. Without it, you don't know what substances your workers are exposed to, what control measures are needed, or whether LEV is required.

A COSHH assessment must:

• Identify the hazardous substances present in your workplace
• Assess the risk of exposure — who's exposed, how, and how much
• Determine what control measures are needed to prevent or adequately control exposure
• Be reviewed regularly and updated whenever work processes change

If the assessment identifies LEV as a control measure, the system must be installed, maintained, tested, and recorded in line with Regulation 9. If you skip the assessment, you've breached Regulation 6 — and you've also got no basis for knowing whether your existing controls (including any LEV) are adequate.

Many businesses install LEV but never revisit whether the system still matches the work being done. A dust extraction system designed for one type of wood processing may be inadequate if you switch to composite materials that generate finer particles. The COSHH assessment should be a living document, reviewed whenever processes, substances, or working patterns change.

Common COSHH Mistakes With LEV Systems

These come up repeatedly in HSE enforcement actions and inspection findings.

Treating PPE as the primary control. Handing out dust masks to workers while a perfectly viable extraction point sits unused (or uninstalled) is a Regulation 7 failure. PPE supplements LEV. It doesn't replace it.

Overdue TExT examinations. The HSE ran 4,000 targeted dust inspections in 2024/25. Overdue or missing TExT reports are among the most common findings. Less than half of companies with LEV systems regularly test them.

No user checks between examinations. A TExT confirms the system works on one day. Without regular user checks, you have no evidence the system was working on the other 400+ days between examinations.

Missing or incomplete records. Having the test done but losing the paperwork puts you in the same position as not testing at all. The law requires you to produce records, not just have them somewhere.

No COSHH assessment, or an outdated one. Without a current assessment, you can't demonstrate that your LEV is the right control measure, or that it's adequate for the substances and processes in your workplace.

Modifying LEV without re-assessment. Adding a new extraction point to an existing system, extending ductwork, or changing the process can all affect system performance. Any modification should trigger a review of whether the system still meets its design specification.

Practical Compliance Steps

Meeting your COSHH obligations around LEV comes down to a repeatable process.

1. Complete your COSHH assessment. Identify substances, assess exposure, determine control measures. If LEV is required, document why.
2. Install appropriate LEV. Designed for your specific substances and processes, not a generic off-the-shelf unit unless it genuinely fits.
3. Commission and record the baseline. When the system is installed, record its design specification and commissioning data. This becomes the benchmark for all future TExT examinations.
4. Set up user checks. Train someone to carry out daily or weekly inspections. Use a sector-specific checklist and record every check.
5. Schedule TExT within 14 months. Book your competent examiner. Use the due date calculator to track the deadline. Set reminders well in advance.
6. Store records securely. Keep TExT reports and user check logs for at least 5 years. Make them accessible for inspection. The record-keeping requirements checker can help identify gaps.
7. Act on findings. Fix problems identified in TExT reports and user checks. Record the repair.
8. Review your COSHH assessment. Revisit it whenever processes, substances, or working conditions change. Update it at least annually as good practice.

COSHH compliance around LEV isn't a one-off project. It's an ongoing cycle of assess, control, maintain, test, record, and review. LEVproof will be a digital tool designed to keep that cycle running without the administrative overhead. Join the waitlist for early access.

Sources

• Control of Substances Hazardous to Health Regulations 2002 (COSHH) — legislation.gov.uk
• COSHH main page — HSE
• HSG258: Controlling airborne contaminants at work — HSE
• LEV guidance for employers — HSE
• Local exhaust ventilation (LEV) guidance — HSE
• Work-related lung disease — HSE

This guide summarises published HSE and government guidance. It does not constitute legal advice. Consult a qualified professional for advice specific to your situation.