Phoenix Journal · LEV & Air Quality
Cut stone, concrete or brick and you release a dust fine enough to reach the deepest part of the lung and stay there. Silica dust kills more construction workers than almost anything else, and it does it quietly, over years.
Silica is one of the most common minerals on earth, present in the rock, sand, concrete, brick and stone that construction and stoneworking handle every day. That ubiquity is what makes it so dangerous. When those materials are cut, ground, drilled or polished, they release respirable crystalline silica, a dust so fine it is invisible in ordinary light and small enough to be breathed into the deepest part of the lung, where the body cannot clear it. The HSE ranks it as the biggest risk to construction workers after asbestos, and the comparison is not made lightly.
The harm is severe and often irreversible. Respirable crystalline silica causes silicosis, a progressive scarring of the lung tissue that permanently reduces the ability to breathe and has no cure. It is classed by the International Agency for Research on Cancer as a Group 1 carcinogen, a confirmed cause of lung cancer, and long-term exposure is also linked to chronic obstructive pulmonary disease and kidney disease. The workplace exposure limit is 0.1 milligrams per cubic metre as an eight-hour average, one of the lowest limits the HSE sets, and even so employers are expected to keep exposure well below it, because for a carcinogen there is no level known to be safe. HSE-linked estimates attribute hundreds of construction worker deaths a year to silica.
The engineered stone problem
What has pushed silica back into the headlines is engineered stone, the man-made quartz composite used for kitchen worktops. It looks and behaves like premium natural stone at a fraction of the cost, but it is made largely of crushed quartz bound in resin, and it can contain over 90 per cent crystalline silica, far more than granite or sandstone. Cutting and polishing it dry generates enormous quantities of respirable dust, and clusters of accelerated silicosis, the disease appearing in younger workers and progressing fast, have been linked to worktop fabrication and installation. The concern is serious enough that some countries, including Australia, have banned high-silica engineered stone outright, and UK cases have prompted calls for tighter regulation.
The UK regulator has responded on the health side. In March 2025 the HSE updated its guidance on health surveillance for those exposed to respirable crystalline silica, specifically naming worktop manufacturing and installation, along with stone masonry, as high-risk occupations where health surveillance must be considered. Where workers are regularly exposed and silicosis could develop, that surveillance, a scheme of repeated health checks, is a legal requirement under COSHH, because control measures are not always reliable and early detection can catch harm before it becomes disabling. Surveillance does not replace control; it is the safety net beneath it.
Because the dust is invisible and the disease is slow, silica rewards exactly the wrong instincts: if you cannot see a problem today and you feel fine, it is easy to assume the controls are adequate. They often are not. Dry cutting with a power tool can generate silica at many times the limit in a single task, and dust drifts and lingers, so a worker who walks into an area after cutting has finished can still be exposed. Compressed air used to blow dust off clothing or surfaces, still a common sight, throws a massive cloud of it straight back into the breathing zone and is prohibited under COSHH for exactly that reason.
How it is actually controlled
Controlling silica is a textbook case of working down the levels rather than reaching for a mask, the discipline set out in the hierarchy of control for real workplaces. On-tool water suppression, which wets the dust at the point of cutting, and on-tool extraction using an H-class vacuum designed for hazardous dust each cut airborne levels dramatically, and used together they are more effective still. Ordinary site vacuums are not enough; the particles are too fine for anything but H-class filtration. Respiratory protection, fit-tested to the wearer, then covers the residual, but only after the engineering controls have done the heavy lifting.
Proving control, not assuming it
The hardest part of silica is that you cannot trust your eyes, so control has to be demonstrated rather than assumed, and that is where a properly run COSHH assessment, done as it actually should be, earns its keep. That means identifying every task that disturbs silica, applying suppression and extraction, keeping the extraction thoroughly examined and tested, and, where uncertainty remains, measuring exposure in the breathing zone to confirm it is under the limit. With a hazard this serious and this quiet, the difference between believing you are controlling it and proving you are is the difference that shows up, years later, in someone's lungs.
Questions
Respirable crystalline silica causes silicosis, an irreversible scarring of the lungs, and is a Group 1 carcinogen that causes lung cancer. Long-term exposure is also linked to chronic obstructive pulmonary disease and kidney disease. The effects often take years to appear, which is part of what makes silica so easy to underestimate on site.
The workplace exposure limit for respirable crystalline silica is 0.1 milligrams per cubic metre as an eight-hour time-weighted average, one of the lowest limits the HSE sets. Because silica is a carcinogen, employers are expected to keep exposure as far below that figure as is reasonably practicable, not merely under it.
Engineered stone used for worktops can contain over 90 per cent crystalline silica, far more than most natural stone, so cutting and polishing it releases very high levels of respirable dust. This has been linked to clusters of accelerated silicosis in fabrication and installation workers, and in March 2025 the HSE named worktop work as a high-risk occupation for health surveillance.
Phoenix Duct Clean · by the numbers
Silica control needs water suppression and H-class extraction that works. Phoenix supports LEV that is examined and proven, not assumed. UK-wide.