Case Studies

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Anonymised case study summaries showing how UK workplace ventilation, LEV and extraction projects are typically scoped, investigated and improved. The examples below are illustrative composites drawn from common assessment patterns in manufacturing, fabrication, commercial buildings and laboratories. They are not verified client testimonials and do not name specific organisations, locations or measured outcomes.

Why we publish anonymised composites

Workplace ventilation assessments often involve commercially sensitive process information, exposure data that belongs to the employer, and engineering details that could identify a specific site. Rather than publish client-identifying case studies, this page describes the kinds of project we routinely encounter and the assessment logic typically applied to each one.

The aim is to give prospective enquirers a realistic picture of what an LEV review, airflow investigation or extraction-system assessment looks like in practice — the problem framing, the measurements that matter, and the themes that usually drive improvement — without overstating the precision of an outcome that depends on a specific site and process.

Manufacturing extraction review

Problem: a production area with several existing LEV hoods is reporting persistent dust deposition on surfaces and intermittent operator complaints downstream of a powder-handling stage. Previous thorough examination records show borderline face velocities at two hoods, but no clear failure.

Assessment approach: review of the COSHH risk assessment and original LEV design intent; walk-through of the process to identify contaminant generation points and operator positions; measurement of hood face velocities, duct transport velocities and system static pressure; observation of operator practice and hood position relative to the contaminant source.

Typical improvement themes: hood geometry that no longer matches a changed process; duct loading reducing transport velocity; a single fan serving too many branches with unbalanced dampers; and procedural drift in how operators position work relative to capture zones. The recommended actions usually combine targeted engineering changes with updated user instructions and a clearer examination schedule.

Welding fume capture improvement

Problem: a fabrication workshop using a mixture of MIG and MMA welding has installed ambient extraction but continues to see visible fume drifting through the breathing zone of welders, particularly during longer runs and overhead work.

Assessment approach: identification of welding processes, consumables and duty cycles; assessment of existing capture arrangements against the source-to-receptor pathway; consideration of on-torch extraction, movable hood arms, downdraught benches and ambient capture-and-filter strategies; review of cross-draughts and general ventilation patterns that may be defeating capture.

Typical improvement themes: ambient extraction alone is rarely sufficient as the primary control for welding fume; on-torch or hood-at-source capture usually needs to be added for routine work; movable extraction arms must be repositioned for each new weld; and general ventilation must be designed not to short-circuit the capture system.

Commercial building IAQ investigation

Problem: occupants in a multi-tenant office report stuffiness, tiredness in the afternoon and intermittent odour complaints, particularly in densely occupied meeting rooms. There is no obvious industrial contaminant source.

Assessment approach: review of the ventilation strategy (mechanical, natural or mixed); measurement of CO₂ as a proxy for outside-air delivery per occupant; spot measurements of temperature, relative humidity and particulate levels; inspection of supply and extract terminals, filters and AHU operation; review of occupancy patterns versus design assumptions.

Typical improvement themes: outside-air delivery that has fallen behind actual occupancy; demand-controlled ventilation set points that are too conservative; blocked, dirty or undersized filtration; and meeting-room layouts that overload local supply. Most fixes are commissioning and control changes rather than new plant.

Laboratory airflow and fume extraction review

Problem: a research or QC laboratory has expanded the work carried out in its fume cupboards and is unsure whether containment, room pressure relationships and general extract are still appropriate.

Assessment approach: review of the substances handled and the containment requirement for each task; face-velocity measurement on fume cupboards across the working sash range; smoke visualisation to confirm capture and absence of roll-back; check of room pressure relationship to adjacent areas; review of make-up air arrangements and the impact on cupboard performance.

Typical improvement themes: face velocities outside the accepted operational range; make-up air imbalances that cause cupboard performance to fluctuate; sash management behaviour that undermines containment; and a need to clarify which tasks belong in a fume cupboard, which in a biosafety cabinet, and which require additional local capture such as a snorkel.

What an enquiry typically leads to

Most enquiries begin with a specific concern — a failed test, a new process, an upgrade decision, an occupant complaint — and end with one of three outcomes: a thorough examination and test against HSG258, a focused ventilation or IAQ assessment, or a scoped engineering review that informs a procurement specification. Where appropriate, the work is staged so that measurement comes before specification, and specification comes before procurement.