Understanding air filtration in dusty work environments.

Air filtration works by pulling contaminated air through a filter that traps the particles and lets clean air through. Simple enough. In practice, what decides whether it works on site is everything around the filter: catching dust close to where it’s made, moving the air fast enough to keep particles suspended, matching the filter to the dust, then sending it outside or back into the room. 

Get the capture wrong and the filter never sees the dust. That’s where most systems fall over. 

Overview. 

• Four steps: capture, convey, filter, discharge or return. A weak link anywhere drags the rest down. 

• Particle size sets the filter grade. The dust that does the damage is usually invisible. 

• From 1 December 2026, Australia’s workplace exposure standards become workplace exposure limits, and dozens of numbers drop. 

• Catching dust at the source beats cleaning the room, and regulators expect engineering controls before respirators. 

• Filtering air on the way in is a different job from extracting it on the way out. 

How a filtration system actually works. 

Four things have to happen, in order. 

Capture. The hood, on-tool shroud or extraction arm has to sit close to where the dust is made. Too far away and as a result it escapes into the general air, where nothing downstream will recover it. 

Convey. Air moves along the duct fast enough that particles stay suspended rather than dropping out along the way. 

Filter. The medium traps the particles. 

Discharge or return. Cleaned air goes outside, or back into the room if the filtration is up to it. 

Fume extraction runs the same way: capture the contaminated air, pass it through filters such as activated carbon, release the cleaned air back into the space. Fanquip’s guide to fume extraction systems goes through the different setups. 

The dust you can’t see is the dust that matters. 

Although dust isn’t one thing, the distinction that matters is inhalable versus respirable. Larger inhalable particles settle in the nose and upper airways. Respirable particles reach the deepest part of the lungs, and those are the ones that cause lasting damage. You generally can’t see them. 

Silica is the clearest case. Respirable crystalline silica comes off cutting, grinding, drilling, polishing and crushing, and the workplace exposure standard is 0.05 mg/m³ as an eight-hour time weighted average. It must not be exceeded. 

That distinction between inhalable and respirable is also what drives equipment selection, because particle size decides the filter grade: 

Carbon does what a particle filter can’t. Gases and vapours pass straight through HEPA, which is why welding setups often run both. Fanquip’s negative air units use AS 1324 tested HEPA filtration for enclosed and confined spaces, and the filtration range covers air purifiers, filter fans and filtered supply air as well. 

The numbers your system was sized against are about to move. 

On 1 December 2026, Australia’s workplace exposure standards are replaced by workplace exposure limits. It’s the biggest reset of airborne contaminant limits in a generation, and because there’s no transition period, the new numbers apply from day one. 

The dust limits that drop. 

For anyone running dust extraction, these are the ones to know: 

Meanwhile the trap is that nothing at the site has to change for a compliant workplace to become non-compliant. The number moves, the site doesn’t. For example, a workshop with respirable manganese at 0.04 mg/m³ was sitting at 4% of the old standard. Against the new 0.02 mg/m³ limit, however, the same reading is double the limit. 

The carcinogens that lose their limits. 

There’s a second change that filtration people should read closely. Thirty-three carcinogens lose their limits entirely, including hexavalent chromium, which comes off any stainless steel welding. As a result, there’s no number to pass. Instead the duty is to eliminate, substitute or reduce exposure so far as is reasonably practicable, and documented source capture is therefore the strongest evidence a site can put forward. 

Fanquip has pulled the full set of changes, the industry-by-industry impact and a readiness plan into one document: The 2026 Workplace Exposure Limit Changes. 

Catching dust at the source beats cleaning the room. 

The breathing zone is a 300mm hemisphere in front of the worker’s face. Catch dust before it crosses that distance and consequently you move less air, pay for a smaller filter, and leave no window where dust is airborne. That’s why regulators put engineering controls above respirators. Fanquip’s mobile fume extractors capture at the weld with a flexible arm, and the extraction range covers roof, wall, exhaust, axial and centrifugal fans for whole buildings. 

Extraction is half the loop. Filtered supply air replaces what comes out and catches dust on the way in. Switch rooms and control enclosures need the same, running filtered air under slight positive pressure so dust can’t get in through the gaps. That’s what filter fans do. 

Getting ahead of the change. 

There are roughly ten weeks until the new limits take effect, and that’s enough time to do this properly. Since a pass against the old standards tells you very little, start by re-baselining monitoring against the December numbers and the right fractions. From there it’s a matter of scoping what needs to change, and in most cases it’s less than people expect: the capture geometry, not the whole system. 

Sites that scope and order engineering controls this year install on their own schedule. Sites that wait for a failed survey install on the regulator’s. Fanquip’s engineers assess sites in person and design around the process and the budget. Talk to Fanquip’s team, or read The 2026 Workplace Exposure Limit Changes for the full set of changes and a readiness plan. 

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