LEV Requirements for Welding Operations

Local exhaust ventilation sits at the engineering control level of the hierarchy of control, making it the most effective reasonably practicable measure for reducing welding fume exposure after elimination and substitution have been considered. The incoming December 2026 workplace exposure limits for manganese, chromium VI, and nickel are so low that general dilution ventilation alone cannot achieve compliance for most welding operations. LEV works by capturing fume at or near the point of generation before it enters the worker's breathing zone. A properly designed and maintained LEV system can reduce welding fume exposure by 90 per cent or more compared to relying on general ventilation alone. The WHS Regulation 2025 requires PCBUs to implement engineering controls before relying on administrative controls or respiratory protective equipment, and regulators will expect to see LEV as the primary control measure for any welding operation that generates airborne contaminants above the applicable WEL.

Fabrication workshops can deploy several types of LEV depending on the welding process, component size, and workshop layout. Extraction arms are the most common LEV type in fabrication workshops. These are flexible ducted hoods mounted on articulating arms that can be positioned within 300 mm of the weld zone. They must provide a capture velocity of at least 0.5 m/s at the fume source to be effective. Downdraft benches extract fume downward through a perforated work surface and are highly effective for welding, grinding, and cutting of components small enough to fit on the bench. Enclosed welding cells contain the welding operation within a physical enclosure with mechanical exhaust ventilation, providing the highest level of fume control and also protecting bystanders. Fume extraction welding guns incorporate extraction into the MIG welding torch itself, capturing fume within centimetres of the arc. Back-draft benches use a vertical extraction slot at the rear of the workbench to draw fume away from the welder. Each system type has advantages and limitations, and most fabrication workshops will need a combination of two or more types to cover all welding stations and processes.

The effectiveness of any LEV system depends on two factors above all others: the capture velocity at the fume source and the distance between the extraction point and the fume source. Capture velocity is the air speed measured at the point where fume is generated. For welding fume, a minimum capture velocity of 0.5 m/s is required at the fume source. However, capture velocity decreases rapidly with distance. At twice the hood diameter from the face of a plain circular hood, the capture velocity has dropped to approximately 7 per cent of the face velocity. This means that an extraction arm positioned 600 mm from the weld zone provides only a fraction of the capture effectiveness of the same arm positioned at 300 mm. Workers must be trained to reposition extraction arms as they move along a weld, and supervisors must verify correct positioning during workplace inspections. For downdraft benches, the face velocity across the perforated surface should be at least 0.5 m/s measured with all slots open. For enclosed welding cells, the exhaust rate must achieve at least 6 air changes per hour within the enclosure volume to maintain fume concentrations below applicable WELs.

LEV systems degrade over time through filter loading, duct blockage, fan belt wear, and damage to extraction arms and hoods. The WHS Regulation 2025 requires PCBUs to maintain engineering controls in effective working order. For LEV systems, this means establishing a documented maintenance and testing schedule that includes daily visual checks of extraction arm positioning and airflow indicators, monthly filter condition checks and replacement as needed, quarterly face velocity measurements using a calibrated anemometer, and annual thorough examination and testing by a competent ventilation engineer. The thorough examination must include face velocity measurements at every extraction point, duct velocity measurements to detect blockages, filter pressure drop readings, fan performance verification against design specifications, and a written report identifying any deficiencies and required corrective actions. All test results must be recorded and retained for at least five years. EHS Atlas automates LEV testing schedules, sends reminders when testing is due, and stores test reports for audit-ready retrieval.

The most common reason LEV systems fail to protect welders is that workers do not position extraction arms close enough to the fume source. This is a training and supervision issue that no amount of engineering investment can overcome without behavioural reinforcement. The second most common failure is blocked or loaded filters that reduce airflow below effective levels. Visual airflow indicators such as manometer gauges or tell-tale streamers at extraction points give workers immediate feedback on whether the system is operating effectively. The third failure mode is damage to extraction arms and flexible duct sections that creates air leaks, reducing capture velocity at the hood. The fourth is inadequate duct sizing that creates excessive pressure drop and reduces extraction volume. The fifth is failure to commission the system properly after installation, meaning it never achieved design performance in the first place. Fabrication businesses should address each of these failure modes in their LEV management procedures and ensure that commissioning verification, worker training, and maintenance testing are all documented and auditable.