Silica Is the Other Asbestos: Why Engineered Stone Changed the Risk (2026)

Respirable crystalline silica is classified as a Group 1 carcinogen, the same category as asbestos, meaning it is known to cause cancer in humans. The disease it is best known for, silicosis, is incurable.

What has changed recently is not the mineral but the material. Engineered stone countertops contain roughly 90 percent silica against about 40 percent for granite and 5 percent for marble, and cutting them has produced silicosis in workers in their thirties, with rapid progression rather than the slow decades-long course the disease used to follow.

Canada has no single exposure limit

This is the first thing to get right, because almost every article on this topic quotes an American number.

Exposure limits are set provincially and they differ by a factor of two. Ontario's regulation on designated substances sets a time-weighted average of 0.05 mg/m³ for respirable quartz. British Columbia's limit is 0.025 mg/m³, half that.

A contractor working across provincial lines is therefore subject to different numbers for identical work, and a control plan built to the looser limit is non-compliant in the tighter jurisdiction.

Crystalline silica is also listed under Schedule 1 of the Canadian Environmental Protection Act as a toxic substance, which brings emissions obligations alongside the worker exposure ones.

Confirm the limit that applies where you work rather than relying on a figure from a supplier's datasheet or an American guidance document.

Where it comes from

Crystalline silica is ordinary. It is in sand, stone, concrete, brick, block, mortar and engineered stone, and it becomes a hazard only when something makes it airborne in respirable form.

Cutting, grinding, drilling, crushing, chipping and abrasive blasting all do that. So does dry sweeping the debris afterward, which is one of the more common uncontrolled exposures because it happens after everyone has decided the job is done.

The exposed trades are broad: construction and demolition, masonry and concrete work, tunnelling and mining, foundry work, sandblasting, and countertop fabrication and installation.

The particles that matter are too small to see. A visible dust cloud tells you exposure is occurring; the absence of one tells you nothing, because respirable particles stay suspended and invisible.

Drywall finishing is a case worth naming because it surprises people. Joint compound can contain silica and sanding it produces fine dust, covered in our guide to PPE for painters and drywallers.

Engineered stone is a different hazard

Treating engineered stone as just another countertop material is the mistake that has produced a wave of young silicosis patients internationally.

CAREX Canada's occupational profile notes that engineered stone contains much higher levels of silica, around 90 percent, compared with granite at about 40 percent and marble at about 5 percent, and that workers are exposed through processes such as cutting.

The respirable dust is worse in proportion too. Peer-reviewed research on engineered stone fabrication found the respirable dust generated contained roughly 57 to 75 percent crystalline silica, against about 25 percent for granite.

The clinical picture that follows is distinctive: disease onset at an early age and rapid progression, rather than the slow accumulation over a working life that characterized classic silicosis. California identified cases from 2019 including fatal ones among workers in their thirties.

The same research found that the proportion of time spent processing engineered stone, and the time spent working without water suppression, were strongly correlated with silicosis risk. That is as close to a direct instruction as occupational research gets.

Water is the control, not the mask

The research finding above puts water suppression ahead of everything else, and it is worth being explicit about why.

Wet cutting suppresses dust at the point it is created, before it enters the air anyone breathes. On-tool local exhaust ventilation with a properly rated dust extractor does the same job where water is impractical. Both are engineering controls and both protect everyone in the area rather than one person.

Without controls, exposure during engineered stone fabrication has been estimated at roughly twelve times the regulatory limits used in exposure studies. With water suppression the same work came in at a fraction of that. The gap between those two numbers is the whole argument.

Work practice controls matter alongside: cutting outdoors or in a dedicated area where possible, keeping others out of the cutting zone, and never dry sweeping. Vacuum with a HEPA-filtered unit or wet clean instead, because a broom or shop vacuum puts the dust back into the air more efficiently than the cutting did.

Respiratory protection comes last, and it is not a substitute for any of the above. Some research indicates that where engineered stone is being fabricated, controls alone may struggle to bring exposures below regulatory limits, which is an argument for substitution rather than for a better mask.

The respirator question, answered carefully

We sell respiratory protection, which makes it important to be precise about what it does here.

A disposable N95 is a particulate filter and it addresses dust rather than gas or vapour, so the filter type is at least the right family for silica. That is a lower bar than it sounds.

For sustained cutting, grinding or fabrication work, a disposable is generally not the right answer. Higher-efficiency filters on a properly fitted elastomeric half or full facepiece, and in some situations powered air-purifying equipment, are what the exposure warrants. The selection follows from measured exposure rather than from what is in the van.

And a respirator that has not been fit tested is not protection at any rating, because the leak path around a poor seal bypasses the filter entirely. Our guide to respirator fit testing under CSA Z94.4 covers what that involves and why facial hair defeats it.

We do not stock wet cutting systems, on-tool extraction units or HEPA vacuums, which are the controls that actually matter here. Those come from tool and dust control suppliers.

What it does to a worker

Silicosis is scarring of the lung tissue that does not reverse. There is no treatment that removes it, and the damage accumulates with exposure.

The classic form develops over ten to thirty years of exposure. Accelerated silicosis develops over roughly five to ten years at higher exposures, and acute silicosis can develop within months where exposures are very high. The engineered stone cases sit in the accelerated and acute end.

Beyond silicosis, respirable crystalline silica is associated with lung cancer, chronic obstructive pulmonary disease and kidney disease, and silicosis increases susceptibility to tuberculosis.

Early symptoms are easy to attribute to something else: shortness of breath on exertion, a persistent cough, fatigue. Any worker with a silica exposure history and those symptoms should be assessed rather than waiting to see.

Health surveillance belongs in a program where significant exposure exists, because the disease progresses silently and by the time breathlessness is obvious, substantial lung function has already gone.

Building a control plan

Start by identifying the tasks rather than the trades. The same worker may have negligible exposure most of the week and a high-exposure hour on Thursday, and the assessment follows the task.

Then work down the hierarchy honestly. Can the cut be eliminated by ordering material to size? Can a lower-silica material be substituted? Can water suppression or on-tool extraction be fitted? Only then does the respirator enter the conversation.

Written exposure control plans are required in several jurisdictions where silica work occurs, covering the tasks, the controls, the housekeeping and the respiratory protection. That document is also what an inspector asks for first.

Train the crew on the specifics, including the two things people get wrong: that invisible dust is the dangerous fraction, and that dry sweeping undoes the controls.

Eye protection and hearing protection belong in the same task assessment, since cutting is loud and throws fragments. See our safety glasses guide and hearing protection guide. Changeable clothing keeps dust out of vehicles and homes, covered in our comparison of coveralls and bib overalls, and hand protection in our guide to work gloves.

For the wider programme see the complete PPE checklist for Canadian workers, our guide to PPE requirements for Canadian construction sites, our guide to who pays for PPE in Canada, our guide to CSA Z1220 first aid kit requirements and our guide to CSA certified versus CSA compliant.

Frequently Asked Questions

What is the silica exposure limit in Canada?

There is no single national limit. Exposure limits are set provincially and differ by up to a factor of two: Ontario sets a time-weighted average of 0.05 mg/m³ for respirable quartz, while British Columbia's limit is 0.025 mg/m³. Confirm the limit where the work is performed rather than using an American figure.

Why is engineered stone more dangerous than granite?

Silica content. Engineered stone contains roughly 90 percent silica against about 40 percent for granite and 5 percent for marble, and the respirable dust it generates runs about 57 to 75 percent crystalline silica compared with around 25 percent for granite. The resulting disease appears earlier and progresses faster.

Is silicosis treatable?

No. Silicosis is scarring of lung tissue that does not reverse, and there is no treatment that removes it. It also increases susceptibility to tuberculosis, and silica exposure is associated with lung cancer, chronic obstructive pulmonary disease and kidney disease.

Is a respirator enough for silica work?

No. Research on engineered stone fabrication found that time spent working without water suppression was strongly correlated with silicosis risk, which puts wet cutting and on-tool extraction ahead of respiratory protection. A respirator is the last control, it must be selected against measured exposure, and it must be fit tested.

If I cannot see dust, am I safe?

No. The respirable fraction that reaches deep into the lungs is too small to see and stays suspended in air. A visible cloud confirms exposure is happening; the absence of one confirms nothing. Dry sweeping after a job is a common uncontrolled exposure for exactly this reason.

Which trades are exposed?

Construction and demolition, masonry and concrete work, tunnelling and mining, foundry work, abrasive blasting, and countertop fabrication and installation. Drywall finishing also counts, since joint compound can contain silica and sanding produces fine dust.

This guide is general workplace safety information, not medical or legal advice. Occupational exposure limits and silica control requirements are set by provincial and territorial regulation and differ between jurisdictions. Confirm yours with the occupational health and safety authority that governs your workplace. Anyone with a silica exposure history experiencing breathlessness, persistent cough or fatigue should be assessed by a healthcare professional.