Phoenix Journal · LEV Testing
Silicosis is the incurable lung disease sitting behind almost every silica dust rule you will read. Here is what it does, why the limits are so strict, and how proper LEV control keeps that fine dust out of people's lungs.
The disease behind the rules
Silicosis is one of the oldest occupational lung diseases we know of, and it sits behind almost every rule you will read about silica dust - because it is incurable, entirely preventable, and still killing workers today.
Silica is a natural mineral found in stone, sand, concrete, brick, mortar and the engineered materials made from them. On its own, sitting in a worktop or a wall, it is harmless. The danger appears the moment that material is cut, ground, drilled or polished, because the process throws off a cloud of extremely fine particles known as respirable crystalline silica, or RCS. These particles are small enough to travel deep into the lungs and lodge in tissue that has no way of clearing them.
Once they are there, the body reacts. Scar tissue forms around the trapped particles, the lung gradually stiffens, and its ability to move oxygen falls away. That scarring is silicosis. It cannot be reversed and there is no treatment that undoes it - once lung function is lost, it stays lost. In its worst form the disease leaves people breathless walking across a room, and it can be fatal. The International Agency for Research on Cancer classes RCS as a Group 1 carcinogen, a confirmed cause of lung cancer, and long-term exposure is also linked to chronic obstructive pulmonary disease.
This is why the rules around silica dust read so strictly. They are not written around a nuisance - they are written around a disease that arrives quietly, sometimes years after the exposure that caused it, and that the Health and Safety Executive estimates contributes to around 500 deaths every year in Great Britain. Every threshold, every control measure and every test exists to keep that fine dust out of people's lungs in the first place.
The cruelty of RCS is in its size. A single respirable particle can be less than a hundredth of the width of a human hair - far too small to see, and light enough to hang in the air long after the cutting has stopped. You can walk into a space that looks perfectly clear and still be breathing a hazardous concentration. That is the trap: the visible dust settles, but the dangerous fraction is the part you never notice.
Because of that, the UK sets the Workplace Exposure Limit for RCS at 0.1 mg/m³ averaged over an 8-hour day - one of the lowest limits on the list, precisely because so little does so much harm. It is worth being clear that this figure is not a safe level. Under the Control of Substances Hazardous to Health Regulations 2002 (COSHH), exposure must be reduced as low as is reasonably practicable, and the limit is simply the line you must never cross, not a target to aim at.
The other feature that makes silicosis so dangerous is time. Traditional silicosis develops slowly, often after ten or twenty years of exposure, which means the damage builds up unseen while everything appears fine. But high concentrations can compress that timeline dramatically. There are now documented UK cases of acute and accelerated silicosis in workers exposed to very high dust levels, where the disease took hold in months rather than decades. By the time symptoms appear, the harm is already done - which is exactly why prevention, not detection, has to come first.
Most people associate silica with construction, and with good reason: cutting kerbstones, chasing walls, grinding concrete and sweeping up brick dust are classic high-exposure tasks. But the material that has pushed silicosis back into the headlines is much closer to everyday life - the engineered stone used for modern kitchen and bathroom worktops.
Engineered, or artificial, stone is a mix of crushed quartz and resin, and it can contain up to around 95% crystalline silica - far more than most natural stone. When a fabricator cuts or polishes it dry, it releases RCS at concentrations that have proved devastating. Since the first UK cases were reported in 2024, further cases have been identified among stone workers, and the HSE has responded firmly. It has made clear that dry cutting of engineered stone is unacceptable, that water suppression and extraction are how the law must be met, and it has committed to a large programme of inspections across the trade, with enforcement against those who fall short. Real penalties have already followed - one stonemasonry firm was fined £18,000 for repeatedly failing to protect its workers.
So where does that leave a commercial kitchen? The everyday work of cooking does not generate silica dust. The risk sits at the edges - during fit-out, refurbishment and maintenance. If a worktop is being cut or dry-shaped on site, if flooring screed or tiling is being ground back, or if brick and concrete are being worked during a building alteration, RCS can be released into the same space your extraction and ventilation serve. Anyone specifying, refurbishing or maintaining a kitchen environment has a stake in understanding it, because the controls that protect a stonemason are the same family of controls - extraction, filtration and airflow - that keep a working kitchen safe day to day. Our companion guide on the health risks every site should know goes further into the tasks and materials that put people in the firing line.
COSHH sets out a clear order of priority. Wherever possible you design the dust out, then you suppress what remains, then you capture it at source. Water suppression - wetting the cut so dust cannot become airborne - and local exhaust ventilation (LEV), which draws contaminated air away from the breathing zone before it can be inhaled, do the heavy lifting. Respiratory protection matters, but it is the last line, not the first, and it only works when the controls behind it are doing their job.
LEV is only as good as its performance on the day, and performance drifts. Ducts clog, filters load up, fans wear, dampers slip and hoods get knocked out of position - all of it invisible until the system is quietly pulling far less than it should. That is why COSHH Regulation 9 requires a Thorough Examination and Test, known as TExT, of every LEV system, carried out by a competent person. For most systems this must happen at least every 14 months, and higher-risk processes need it more often.
A proper TExT is not a glance and a signature. It measures airflow against the system's original commissioning figures, checks the condition of hoods, ductwork and filters, and produces a written report confirming whether the system still controls exposure adequately - or setting out exactly where it has fallen short. Those records must be kept for at least five years and made available to an HSE inspector on request. In an enforcement climate this active, that paperwork is often the difference between demonstrating control and being unable to prove anything at all.
The thread running through all of it is the same one we started with: silicosis is incurable but entirely preventable. The dust rules are not red tape - they are the accumulated response to a disease that has taken far too many lives, and they reward the businesses that keep their controls maintained, tested and documented. Get the extraction right and prove it works, and you protect the one thing none of it can give back.
Questions
No. The UK Workplace Exposure Limit for respirable crystalline silica is 0.1 mg/m³ averaged over an 8-hour day, but this is a legal maximum you must not exceed, not a threshold below which exposure is harmless. Under COSHH you are required to reduce exposure as low as is reasonably practicable, which means using suppression and extraction to get well below the limit rather than treating it as a target.
Under COSHH Regulation 9, a Thorough Examination and Test (TExT) of your LEV must be carried out by a competent person at least every 14 months for most systems, and more frequently for certain higher-risk processes. The test measures airflow against the original commissioning data and checks hoods, ducts and filters, then produces a written report. Those records must be kept for at least five years and shown to HSE on request.
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