Local exhaust ventilation (LEV)

Local exhaust ventilation (LEV) is an engineering control that captures airborne contaminants (dust, fumes, vapours) at or near the source before they spread into the work area and the worker’s breathing zone. It sits among the higher-order controls in the WHS hierarchy, above respiratory protection.

What it is made of:

A hood or capture point at the source.
Ducting carrying the contaminated air away.
An air cleaner or filter (for hazardous construction dusts, an M- or H-class unit).
A fan and a discharge point.

In construction it shows up as:

On-tool dust extraction: the LEV is mounted on the power tool and captures dust as it is cut. The most common construction LEV.
Fixed or booth extraction: a hood or booth over a fixed work point such as a cutting station or welding bay.
Mobile dust extractors: portable units positioned near the work.

Why it matters: for respirable crystalline silica, welding fume, and wood dust, LEV (often combined with wet methods) is the primary engineering control, and PPE is worn on top, not instead. But LEV only works if it actually captures: the hood has to be close to the source with enough capture velocity, and the filter has to be the right class and kept clean. An undersized, poorly positioned, or clogged system gives a false sense of safety.

Maintain and test it: capture performance degrades with clogged filters, kinked ducts, and worn fans, so it needs checking, not just installing.

Also known as: LEV, source capture, extraction ventilation.

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