HSG258 Explained: A Duty Holder's Guide

HSG258 is the HSE's guide to LEV under COSHH Regulation 9 — duty holder obligations, the 14-month interval, and how LEV fits with LOLER and PSSR.

About this guide

This page explains HSG258 for duty holders researching the regulatory framework around Local Exhaust Ventilation (LEV). EIS does not provide LEV testing. This is a duty-holder reference covering the COSHH regulatory context and how it interacts with the LOLER, PUWER, and PSSR examinations EIS does carry out. For the practical examination-side detail, see the companion LEV duty-holder guide.

What is HSG258?

HSG258 is the Health and Safety Executive’s published guidance document titled Controlling Airborne Contaminants at Work: A Guide to Local Exhaust Ventilation. It is the operational guidance the HSE expects duty holders and competent examiners to work to when designing, commissioning, maintaining, and testing LEV systems under COSHH Regulation 9. HSG258 is free to download from the HSE website and applies to any workplace where airborne contaminants — dust, fume, vapour, mist — are generated and where LEV is used as the primary engineering control.

The guide is technical but accessible. It sits behind almost every LEV inspection report a duty holder will ever receive, and understanding its structure helps duty holders read those reports properly.

What HSG258 is and where it sits in the COSHH framework

HSG258 is operational guidance — not legislation itself. The legal duties sit in two places in the Control of Substances Hazardous to Health Regulations 2002 (COSHH):

• COSHH Regulation 7 — Control of exposure. Duty holders must prevent or, where prevention is not reasonably practicable, adequately control employee exposure to substances hazardous to health. Where engineering control measures (such as LEV) are used, those measures must be applied in line with HSE guidance.
• COSHH Regulation 9 — Maintenance, examination and test of control measures. Engineering controls used to comply with Regulation 7 must be maintained in efficient working order, in efficient state, in good repair, and in a clean condition. LEV specifically must be thoroughly examined and tested at suitable intervals by a competent person.

HSG258 is the operational guide that tells duty holders how to meet Regulation 9 for LEV. It describes what good LEV design looks like, what commissioning data should be captured at installation, what an examination must measure, what a compliant report should contain, and what records the duty holder must retain. The HSE’s enforcement officers refer to HSG258 when they look at LEV during workplace inspections — which is why a report formatted to HSG258 is the practical evidence of compliance.

It’s worth distinguishing HSG258 from the BOHS P601 qualification. HSG258 is the regulatory guidance — what should be done. P601 is the competence standard — held by the people who do the testing. The two are often confused; the section below covers the distinction.

Who HSG258 applies to

HSG258 applies wherever LEV is used as a primary control under COSHH. In practice that catches a very wide range of workplaces:

• Woodworking and joinery — dust extraction on saws, planers, sanders, downdraft tables, and centralised dust-collection systems.
• Welding and metal fabrication — weld fume extraction (on-tool, capture hood, ambient) is one of the HSE’s highest enforcement priorities since the 2019 reclassification of mild-steel welding fume as a Group 1 human carcinogen.
• Spray painting and surface finishing — paint spray booths, prep stations, and mixing rooms; heavy HSE enforcement focus.
• Soldering and electronics assembly — solder fume arms, conformal coating extraction, and reflow oven venting.
• Pharmaceutical and laboratory work — fume cupboards, weigh booths, isolators, dedicated process extraction.
• Food processing — flour and sugar dust extraction in bakeries, mills, and food manufacturing.
• Dental laboratories — dust and aerosol extraction at workbenches and CAD/CAM milling stations.
• Vehicle workshops, MOT bays, and bodyshops — exhaust gas extraction during diagnostic work, brake dust extraction, and paint booth systems.
• Construction — extraction fitted to grinding, sanding, cutting, and concrete-scabbling operations.
• Commercial kitchens — kitchen extract canopies acting as the primary COSHH control for cooking emissions.

Wherever LEV is the engineering control protecting workers from a COSHH substance, HSG258 is the operational standard the system is examined against. EIS works with duty holders across many of these sectors on the LOLER, PUWER, and PSSR side — but the LEV testing itself needs a separately-commissioned, P601-qualified examiner.

What HSG258 requires duty holders to do

HSG258 sets out the duty holder’s responsibilities across the full LEV lifecycle. The headline requirements:

• Design and selection (HSG258 Sections 2–4). LEV must be designed to capture the specific contaminants at source — generic extraction is not enough. The design should reflect the substance properties, the process, the operator position, and the volume of contaminant generated. Where a system is being specified, the duty holder is expected to commission a competent designer rather than purchase off-the-shelf equipment without an assessment.
• Commissioning and acceptance tests (HSG258 Section 5). When LEV is installed, an acceptance test should be performed and the commissioning data — face velocities, capture envelopes, system static pressures, motor currents — should be captured as the baseline against which all future examinations are compared. A duty holder who inherits a system without commissioning data will pay slightly more for the first thorough examination because the baseline has to be re-established from observation.
• Thorough examination and test at least every 14 months (HSG258 Section 6, COSHH Schedule 4). The statutory examination interval. Some processes — certain asbestos and crystalline silica operations — require shorter intervals. The 14-month maximum is the law; HSG258 sets the technical scope.
• Maintenance to design specification (HSG258 Sections 7–8). Between formal examinations, the LEV must be kept performing to its commissioned specification. Filter changes, fan belt tension, hood damage repair, and ducting cleaning all sit here.
• User checks. Operators using LEV equipment should perform daily or weekly visual checks — capture hood condition, smoke ribbon for visual airflow confirmation, gauge readings where fitted, audible alarms. HSG258 expects these to be documented in some form.
• Record keeping. Examination reports must be retained for at least five years. Many duty holders retain them indefinitely; the practical retention floor is five.

The duty holder is the employer, building operator, or site operator with control of the LEV system. The duty cannot be contracted away — even where day-to-day maintenance is handled by a third party, the duty holder remains responsible for ensuring HSG258-compliant examinations happen on time.

The 14-month thorough examination and test interval

The most-asked question on HSG258 is why 14 months — not 12, not annual? The answer is practical. The HSE’s drafting recognises that requiring a fixed 12-month interval would force duty holders to chase calendar dates against operational shutdowns, holiday weeks, and staff availability. A 14-month maximum gives the system roughly two months of scheduling flexibility either side of an annual cadence without slipping past the legal interval between two consecutive examinations. In practice, most duty holders schedule LEV examinations on a rough 12-month rhythm and use the headroom to absorb operational realities — exactly as the regulation intends.

What a compliant HSG258 thorough examination covers (in scope-summary form):

• Visual condition of every hood, duct run, junction, fan, motor, filter, and discharge point.
• Qualitative testing at each capture point — smoke ribbon or dust tracer demonstrating how air is actually being drawn into the hood, including under operational conditions.
• Quantitative measurements — face velocity at each hood with a thermal anemometer, system static pressure at multiple points, duct velocity, fan motor current.
• Filter integrity — pressure differential across filters, condition of media, leakage past the filter, discharge cleanliness.
• Ducting integrity — joints, supports, condition of flexible sections, accumulated deposits, leak testing where deficiencies are suspected.
• Discharge of treated air — height, position relative to building openings and prevailing wind, evidence of re-entrainment into the workplace.

A compliant test report compares each measurement against the commissioning data (where available) or against HSG258 benchmark values. Every hood is recorded individually so the duty holder can see which capture points are compliant, marginal, or non-compliant. A single non-compliant hood doesn’t necessarily fail the whole system, but it does mean COSHH control at that specific workstation is not being delivered, and the duty holder must act on the specific deficiency.

Who can do the testing? A person holding the BOHS P601 qualification (Initial Appointed Person LEV Examination and Testing) or someone with equivalently demonstrable HSG258 competence. EIS does not provide LEV testing — engage a P601-qualified examiner directly. The companion LEV duty-holder guide covers what a compliant report should contain in more detail.

HSG258 vs P601 — which is which

Duty holders researching LEV compliance often see HSG258 and P601 named together and assume they’re the same thing. They’re not.

• HSG258 is the regulatory guidance. It tells duty holders and examiners what a compliant LEV system looks like and how it should be examined. It’s published by the HSE, free to download, and updated periodically. Every LEV examination report should be formatted to HSG258 — that’s the link between the testing work and the regulatory expectation.
• BOHS P601 is the competence qualification held by the people who carry out LEV examinations. It’s a structured course leading to a certificate of competence in the technical practice of LEV testing — measurement techniques, instrument calibration, report writing, and the science of airflow capture.

Read together: HSG258 is the standard; P601 is the proof that the person doing the work is competent against that standard. A compliant LEV report cites HSG258 as the technical reference and the examiner’s P601 (or equivalent) as their competence basis.

How LEV under HSG258 connects to LOLER and PUWER inspections

A great many sites that need LEV testing under HSG258 also need LOLER, PUWER, and PSSR examinations. Some examples of how the regimes commonly stack on a single site:

• Woodworking shops typically have lifting accessories (slings, chain blocks, eye bolts) under LOLER, fixed machinery under PUWER, and dust extraction under HSG258/COSHH.
• Welding fabrication shops have overhead cranes and lifting hoists (LOLER), pillar drills and grinding machinery (PUWER), and weld fume extraction (HSG258/COSHH).
• Pharmaceutical facilities have lifting equipment for vessel charging (LOLER), autoclaves and process pressure vessels (PSSR), and fume cupboards, weigh booths, and process extraction (HSG258/COSHH).
• Vehicle workshops have vehicle lifts (PUWER), brake and tyre tools (PUWER and LOLER for any lifting accessories), and exhaust gas extraction and bodyshop paint booth systems (HSG258/COSHH).

EIS provides independent thorough examinations under LOLER, PUWER, and PSSR but does not provide LEV testing. LEV needs to be commissioned from a P601-qualified examiner directly. Where multi-regime compliance work is being planned, scheduling LEV testing alongside the LOLER, PUWER, and PSSR cycle keeps the operational disruption to one compliance window even though the work is delivered by separate providers. That coordination is purely operational — it doesn’t require any commercial relationship between EIS and the LEV testing firm, and EIS doesn’t act as a broker for LEV work.

For cost-side context on the regimes EIS does cover, the LOLER inspection cost guide and the PSSR inspection cost guide walk through what affects pricing on the inspection side — useful background when buyers are budgeting multi-regime compliance work that includes LEV from a separate provider.

What a duty holder should ask before commissioning LEV work

Duty holders frequently read HSG258 looking for a buyer’s checklist — questions to put to a prospective LEV testing provider to confirm the work will actually meet the standard. A short list that surfaces the structural questions:

• Are you P601-qualified, or what equivalent demonstrable competence do you hold? The HSE expects the examiner’s competence to be specifically cited on the test report.
• Will the report be formatted to HSG258? A compliant report follows the structure HSG258 describes — visual inspection, qualitative testing, quantitative measurement, hood-by-hood recording, comparison against commissioning data.
• What measurements will you take at each hood? Face velocity, capture velocity, and static pressure at minimum; HSG258 also expects duct velocities where applicable. Ask which instruments are used and when they were last calibrated.
• Will the report compare measurements against the original commissioning data? If no commissioning data exists, the examiner should explain how the baseline is being re-established and what reference values are being used.
• How are defects reported and rectification recommendations communicated? A useful report categorises deficiencies by urgency (immediate, prompt, observation) rather than lumping them together.
• What’s the record retention provision? The duty holder needs reports retained for at least five years; the examining firm typically retains a copy too, but the duty holder’s responsibility is primary.
• Will a system label be affixed showing the result? HSG258-compliant practice typically includes a green/amber/red system label so operators can see the result at a glance.

These are the questions HSG258 essentially writes for the duty holder — knowing them in advance turns a quote comparison from a price line-up into a meaningful conversation about competence and scope.

Where to find HSG258

HSG258 is published by the HSE and free to download from the HSE’s publications area at hse.gov.uk. Search the HSE site for “HSG258” or “Controlling Airborne Contaminants at Work” to find the current edition. The HSE updates HSG258 periodically — always check the date on any downloaded copy against the current version listed on the HSE site.

Frequently Asked Questions

What is HSG258?

HSG258 is the HSE’s published guide titled Controlling Airborne Contaminants at Work — the operational guidance that underpins how Local Exhaust Ventilation (LEV) systems should be designed, commissioned, maintained, and tested under COSHH Regulation 9. It’s the technical reference any compliant LEV examination report is formatted against.

When does HSG258 apply to my workplace?

HSG258 applies wherever LEV is used as a primary engineering control under COSHH Regulation 7 — woodworking, welding, spraying, soldering, food processing, dental laboratories, pharmaceutical and laboratory work, vehicle workshops, construction grinding/cutting operations, and commercial kitchens are common settings. Whenever the LEV is what’s protecting workers from a COSHH substance, HSG258 sets the standard the system is examined against.

How often does LEV need testing under HSG258?

The default statutory maximum interval is 14 months, set by COSHH Schedule 4. Some specified higher-risk processes require shorter intervals — six-monthly for certain crystalline silica operations and casting blasting, and monthly for some asbestos processes. The 14-month maximum is the law; most duty holders schedule on a rough 12-month rhythm and use the headroom to absorb operational realities.

Who can carry out LEV testing under HSG258?

A person holding the BOHS P601 qualification (Initial Appointed Person LEV Examination and Testing) or someone with equivalently demonstrable HSG258 competence. The examiner’s competence should be specifically cited on the report. EIS does not provide LEV testing — engage a P601-qualified examiner directly. EIS does provide LOLER, PUWER, and PSSR examinations on related compliance work.

Does HSG258 apply if my LEV system was installed before COSHH 2002?

Yes. HSG258 applies to any LEV currently in use as a primary control, regardless of when the system was installed. The challenge with older systems is that original commissioning data may not exist, which means the first examination must re-establish baseline performance from HSG258 benchmark values rather than the original design specification. That’s a more involved piece of work than a routine recall examination on a documented system.

What records does HSG258 require duty holders to keep?

Examination reports must be retained for at least five years. Many duty holders retain them indefinitely as part of their broader health and safety record-keeping. The system label affixed to the LEV is typically a summary; the full report is the authoritative document and should be available for inspection by enforcement bodies.

Does EIS provide LEV testing?

No. EIS does not offer LEV testing as a service. This guide explains the HSG258 regulatory framework for duty holders. If you need related LOLER, PUWER, or PSSR thorough examinations on the same site, EIS does carry those out — see our lifting equipment and PSSR inspection service pages, or the companion LEV duty-holder guide for the LEV-side regulatory context.

How does HSG258 interact with COSHH Regulation 9?

COSHH Regulation 9 is the legal duty to maintain, examine, and test engineering controls (including LEV). HSG258 is the operational guidance that tells duty holders how to meet that legal duty for LEV systems specifically. Compliance with HSG258 is the practical evidence of compliance with Regulation 9 — the HSE’s enforcement officers refer to HSG258 when assessing LEV during workplace inspections, which is why HSG258-formatted reports are the standard form of compliance evidence.