LEV Testing Under COSHH: A Duty Holder's Guide

Local Exhaust Ventilation (LEV) is engineering control equipment used to capture airborne contaminants at source — welding fume, wood dust, paint mist, solder fume, flour dust, pharmaceutical particulates, and many process emissions. Where LEV is the primary control measure for a hazardous substance, the Control of Substances Hazardous to Health Regulations 2002 (COSHH) require it to be thoroughly examined and tested at least once every 14 months by a competent person.

The duty holder — typically the employer — is responsible for ensuring LEV testing happens on time and that the report and label are retained as evidence of COSHH compliance. Failure is a common cause of HSE Improvement and Prohibition Notices, particularly in welding fabrication shops, woodworking facilities, paint and body shops, and process plants where the LEV system has slowly drifted out of specification without anyone measuring it.

When LEV testing is legally required

COSHH Regulation 9 imposes the duty to maintain LEV equipment in efficient working order, efficient state, good repair, and clean condition, and to ensure it is thoroughly examined and tested at suitable intervals by a competent person. Schedule 4 of COSHH then sets the statutory test interval at no more than 14 months for most LEV, with shorter intervals for specified higher-risk processes:

• 14 months — the default maximum interval for LEV serving the great majority of processes covered by COSHH.
• 6 months — required for blasting of castings and processes involving certain crystalline silica operations.
• Monthly — required for some asbestos processes (governed by the Control of Asbestos Regulations alongside COSHH).

The HSE guidance document HSG258 — Controlling Airborne Contaminants at Work: A Guide to Local Exhaust Ventilation — is the technical standard the examination is conducted against. A compliant LEV report demonstrates the system has been examined in accordance with HSG258 by an examiner holding the recognised P601 competence (the BOHS Initial Appointed Person LEV Examination and Testing qualification) or equivalent.

The 14-month interval is the longest the law permits, not the recommended interval. Where a system shows signs of degradation — reduced capture at a hood, visible dust escape, blocked filters between examinations — testing more frequently is the safer course.

What a compliant LEV examination covers

HSG258 sets out three layers of examination — visual, qualitative, and quantitative — and a compliant test must address all three:

• Visual inspection — the overall condition of every hood, duct run, junction, fan, motor, filter, and discharge point. Obvious wear, damage, blockages, missing parts, and modifications since the last test are recorded.
• Qualitative testing — smoke or dust testing at each capture point to visualise how air is being drawn into the hood. This catches the failures that pure airflow numbers miss: turbulence in the capture envelope, dead zones around large workpieces, draughts overpowering capture.
• Quantitative measurement — face velocity at each hood with a thermal anemometer or rotating vane anemometer, system static pressure at multiple points, duct velocity where applicable, and fan motor current. Each measurement is compared with the original design specification or against HSG258 benchmark values.
• Ducting integrity — joints, supports, condition of flexible sections, presence of accumulated deposits, leak testing where deficiencies are suspected.
• Filtration condition — pressure differential across the filter, condition of the filter media, leakage past the filter, and discharge cleanliness.
• Exhaust discharge — height, position relative to building openings and prevailing wind, evidence of re-entrainment into the workplace, condition of the stack and weather cap.

Each hood should be recorded individually in the report so the duty holder can see which specific capture points are compliant, which are marginal, and which are non-compliant. A single non-compliant hood doesn't necessarily mean the whole system fails — but it does mean the COSHH control at that workstation is not being delivered, and the duty holder needs to act on the specific deficiency.

Industries that typically require LEV testing

LEV examination is commonly required across:

• Welding and fabrication — weld fume extraction is high on the HSE's enforcement priority list since the 2019 reclassification of mild steel welding fume as a Group 1 human carcinogen.
• Woodworking and joinery — wood dust LEV on saws, planers, sanders, downdraft tables, and central dust collection systems.
• Vehicle bodyshops and paint spraying — paint spray booths, prep stations, and mixing rooms. Heavy enforcement focus from HSE.
• MOT bays and garages — exhaust gas extraction during testing, and brake dust extraction.
• Electronics manufacturing — solder fume arms, conformal coating extraction, and reflow oven venting.
• Food and beverage production — flour and sugar dust extraction in bakeries, mills, and food manufacturing.
• Dental laboratories — dust and aerosol extraction at workbenches and CAD/CAM milling stations.
• Pharmaceutical and chemical operations — fume cupboards, weigh booths, isolators, and process containment.
• Laboratories and research facilities — fume cupboards, ducted safety cabinets, and dedicated process extraction.
• Commercial kitchens — kitchen extract canopies under the same regulatory framework where they're the primary control.

Common LEV systems that fall under COSHH Regulation 9

LEV comes in many forms. The systems most commonly requiring examination are:

• Fume cupboards (laboratory and educational)
• Downdraft benches and grinding tables
• Capture hoods and on-tool extraction (welding, grinding, cutting)
• Weld fume extraction arms and high-vacuum systems
• Wood dust collectors (single-point and centralised)
• Paint spray booths (cross-draught, downdraft, semi-downdraft)
• Solder fume arms and bench extractors
• Kitchen extract canopies acting as primary COSHH control
• Process extraction on chemical reactors, dryers, and mixers
• Dust collectors, bag houses, and cyclone separators serving the above

What a compliant LEV test report should contain

Each LEV examination should produce a written report formatted to HSG258 plus a system label. A compliant report covers:

• System identification, location, and the process(es) it serves.
• Hood-by-hood photographs, measurements, and assessment.
• Comparison of measured performance against the original commissioning data or HSG258 benchmark values.
• Identified deficiencies and recommendations, categorised by urgency.
• An overall pass / fail conclusion for the system.
• The examiner's name, competence (P601 or equivalent), and signature.
• The recommended date of the next examination.

A green / amber / red label is typically affixed to the system itself summarising the result. The full report is retained by the duty holder; COSHH requires the previous five years' reports to be available for inspection by enforcement bodies.

Where deficiencies are identified, the system should be re-examined after rectification to confirm compliance. The re-examination is normally a shorter visit focused on the specific items raised in the original report.

How LEV testing fits with LOLER, PUWER, and PSSR compliance

Many duty holders find LEV testing falls in the same compliance cycle as LOLER and PUWER thorough examinations and PSSR pressure-system examinations. Garages, fabrication shops, woodworking facilities, and food production sites typically have all four regimes in scope.

EIS doesn't provide LEV testing directly — engage a P601-qualified LEV examiner for that. EIS does provide independent thorough examinations under the related regimes:

• LOLER inspections — lifting equipment, hoists, slings, dock levellers, accessories
• PUWER inspections for garage equipment — vehicle lifts, workshop machinery
• PSSR inspections — air receivers, steam systems, autoclaves, process pressure equipment

If you're coordinating multi-regime compliance across a single site, schedule LEV testing alongside the LOLER/PUWER/PSSR cycle so the operational disruption happens once.

Frequently Asked Questions