Crystalline Silica Safety in Canada: Exposure Limits & the Law

When concrete, stone, brick, or sand is cut, ground, drilled, or crushed, it can release respirable crystalline silica, dust fine enough to lodge deep in the lungs. Inhaling it can cause silicosis, an incurable and sometimes fatal lung disease. The International Agency for Research on Cancer (IARC) classifies crystalline silica dust in the form of quartz or cristobalite as a Group 1 human carcinogen. In Canada there is no single national exposure limit: the number, and the law behind it, depends on where you work. 1,2

What is crystalline silica, and where is silica dust found?

Respirable crystalline silica is airborne silica dust: crystalline silica particles small enough to reach deep into the lungs. It can be released when silica-containing materials like concrete, stone, and sand are cut, ground, or drilled. Quartz is the most common form of crystalline silica; cristobalite is another form. 4,2

Crystalline silica itself is a naturally occurring mineral found in sand, stone, concrete, brick, and mortar. The main occupational concern is breathing in the respirable dust generated when these materials are disturbed. That is why silica dust is a concern in construction, mining, quarrying, tunnelling, foundries, and manufacturing. The absence of visible dust does not show that the air is safe. 4,21,17

Quick facts: quartz silica

These classifications describe the specified substance and form. Consult the safety data sheet for the product being used. 1,3,2

What are the health effects of silica dust exposure?

Breathing in respirable crystalline silica damages the lungs and can affect other organs. Many of these effects take years to appear and cannot be reversed, which is why preventing exposure matters. 4,5

Silicosis

Silicosis is a progressive and incurable lung disease caused by inhaling silica dust. In chronic and accelerated silicosis, the particles cause inflammation and scarring (fibrosis), which steadily reduces the ability to breathe. Symptoms include shortness of breath, a persistent cough, and fatigue, and the disease can continue to worsen even after exposure stops. Silicosis is usually described in three forms: 4,21

• Chronic silicosis: the most common form, which usually appears after 10 or more years of exposure to lower levels of silica dust.
• Accelerated silicosis: develops within about 5 to 10 years of exposure to higher levels of silica dust and progresses faster.
• Acute silicosis: can develop after just weeks or months of exposure to very high concentrations. Fluid builds up in the lungs, and the disease can be fatal.

These are typical patterns, not guaranteed timelines. Because there is no cure, the focus is on preventing exposure and detecting disease early. 5

Lung cancer

The IARC classifies crystalline silica in the form of quartz or cristobalite dust as a Group 1 carcinogen, meaning it is known to cause cancer in humans. Occupational exposure causes lung cancer, including in non-smokers. 2

COPD and tuberculosis

Silica exposure increases the risk of chronic obstructive pulmonary disease (COPD). Workers exposed to silica, including those with silicosis, are also at increased risk of tuberculosis. 4,5

Kidney disease

Prolonged exposure may also increase the risk of chronic kidney disease, including chronic renal failure. 5,3

Is silica as dangerous as asbestos?

Both are serious workplace hazards that can cause lung cancer and irreversible lung damage. Their risk depends on the material, the work being done, and the exposure. Canada prohibits most uses of asbestos and asbestos-containing products, with limited exceptions; existing asbestos-containing materials still require careful management. Silica is present in everyday materials like sand, stone, and concrete, so employers must prevent and control the dust generated by their work. 6,4

What are Canada’s silica exposure limits?

There is no single silica exposure limit in Canada. For respirable quartz, many jurisdictions use 0.025 mg/m³. Quebec, Saskatchewan, the Northwest Territories, and Nunavut set 0.05 mg/m³. Ontario sets 0.10 mg/m³ for quartz and 0.05 mg/m³ for cristobalite. Yukon uses a dust formula rather than one fixed quartz concentration. The table links each value to its own legal basis.

The values below are for the respirable fraction of quartz, expressed as an 8-hour time-weighted average (TWA) in milligrams per cubic metre of air (mg/m³), except for Yukon’s formula. They are not limits for total dust or for every form of silica. Longer shifts and sector-specific rules may require a different assessment.

Respirable quartz exposure limits by Canadian jurisdiction

Yukon’s formula produces a permitted concentration of dust based on its quartz content; it is not directly interchangeable with the fixed respirable-quartz values in the other rows. Use the applicable sampling method and Table 10 calculation rather than treating Yukon as an ACGIH adopter. 27

An exposure limit is a legal maximum, not a safe target. Good practice, and in some jurisdictions the law, is to keep worker exposure as low as reasonably achievable. Air sampling is commonly used to confirm that controls keep exposure below the limit that applies to the workplace. 10,13,22

How is silica exposure controlled?

Silica exposure is controlled using the hierarchy of controls. First consider eliminating the dust-generating task or substituting a less hazardous material or process. The most effective remaining measures remove or contain dust at the source; personal protective equipment is the last line of defence. 7,28

Engineering controls. Wet cutting and wet methods, local exhaust ventilation (dust extraction fitted to tools), and enclosed or isolated processes reduce airborne dust where it is created. These are key long-term controls. 28,22

Administrative controls and safe work procedures. Depending on the jurisdiction and the level and type of exposure, an employer may be required to develop a written exposure control plan (ECP), a code of practice, or other documented control procedures. These may cover tool-specific procedures, restricted access zones, work scheduling to limit exposure time, and training on high-risk tasks such as cutting or grinding concrete. 28,14

Personal protective equipment (PPE). Where respiratory protection is required, workers need an appropriately selected respirator with the required filter efficiency and assigned protection factor (APF), based on the assessed exposure and the applicable requirements. Tight-fitting respirators require fit testing. Protective eyewear and coveralls help limit exposure and contamination. A respirator only protects the worker if it is the right type for the task and is worn correctly. 1,15

Housekeeping and decontamination. Avoid dry sweeping and compressed-air cleaning, because they put silica dust back into the air. Use HEPA vacuuming or wet methods wherever practicable, and follow any restrictions that apply in your jurisdiction. Use the washing and changing facilities required by the workplace’s exposure-control procedures to avoid carrying dust into clean areas or home. 1,28

Air monitoring. Air sampling may be required and is commonly used to measure how much respirable silica workers are breathing, to assess exposure, and to verify that controls are working. 28,20

Health surveillance. Where required or indicated by the applicable occupational health surveillance program, medical monitoring such as lung function tests and chest imaging helps detect silica-related disease in workers who are at risk. Medical monitoring does not replace exposure prevention. 22,27,5

What are the silica dust regulations in Canada?

Federal legislation

In workplaces covered by Part II of the Canada Labour Code and the Canada Occupational Health and Safety Regulations, employers must identify hazards, control them, and train workers. The workplace exposure limit for quartz is set through the regulations’ incorporation of ACGIH values. The applicable TLV is 0.025 mg/m³ for respirable quartz. 29,7,8

Provincial and territorial legislation

Provincial and territorial occupational health and safety laws set their own silica requirements for workplaces under their jurisdiction. Exposure monitoring, a written exposure control plan or code of practice, and specific training are required where the applicable jurisdiction and the circumstances call for them. The exposure-limit table identifies the governing instruments. 13,28,22

In Ontario, construction employers must apply Regulation 833’s exposure limits as well as the dust-control requirements in O. Reg. 213/91, including section 46. An exposure-estimation tool can help plan controls, but it does not replace these legal duties. 15,16

Who must be trained on silica hazards, and who is responsible?

Employers are responsible for giving workers who may be exposed to respirable crystalline silica the information, instruction, and training they need to work safely. Each jurisdiction words this obligation differently. Training must address the actual hazards, work procedures, equipment, and protective measures workers will use. 29,7,28

Silica awareness training is needed in any industry where silica dust may be generated or present, including:

• Construction (for example, concrete sawing, jackhammering, and demolition)
• Mining and quarrying
• Foundries and metal casting
• Ceramics, glass, and brick manufacturing
• Oil and gas services (for example, hydraulic fracturing and abrasive blasting)
• Tunnelling and cement work
• Any work that involves cutting, grinding, or crushing silica-containing materials

Workers who perform high-dust tasks, or who work in confined spaces with poor ventilation, need training and controls that match their exposure risks. 4,21

Because silica awareness training is knowledge-based, it can be delivered in a classroom or online. Employers are responsible for choosing the right training for their workplace, so workers should confirm that their employer accepts the course. Online awareness training does not replace workplace-specific instruction or any required hands-on respirator training and fit testing. 7,28,15

What must workers be taught about silica, and does the training expire?

What must silica instruction cover?

Silica awareness training should cover the properties and health effects of respirable crystalline silica, routes of exposure, occupational exposure limits, engineering and administrative controls, safe work practices, air monitoring, and the purpose and limitations of personal protective equipment such as respirators. 7,28 Where British Columbia’s silica rules apply, instruction and training must also cover the correct selection, fitting, use, care and maintenance of the required protective equipment and the housekeeping practices for silica dust. Where the federal regulations apply, the employee education program must also include the hazard information on the safety data sheet and label, the procedures for safe handling and disposal, including emergency measures, and how to access the exposure reports, training records and safety data sheets. 28,7

A certificate issued by a course provider is evidence that the course was completed. It is not a government certification, and it does not replace the workplace-specific training and instruction that employers must provide under the applicable legislation. 7,28

Does the law set an expiry date for the training?

There is no single Canada-wide legal expiry period for a silica awareness course certificate in the legislation cited here. The eSafetyFirst Silica Awareness certificate carries a printed expiry of three years from completion; that is our program’s practice, not a legal requirement. The employer’s training duties continue regardless of a certificate’s date. For example, the federal regulations require the education and training program to be reviewed at least annually and when conditions or hazard information change. This is a program-review requirement, not an annual certificate expiry. 7

This three-year term is eSafetyFirst’s program policy, separate from statutory duties and the employer’s refresher requirements. Training should be revisited when the work, equipment, hazards, or a worker’s demonstrated understanding changes. 7,28

Key takeaways

Respirable crystalline silica is a serious hazard on Canadian worksites, and silicosis cannot be cured. Employers must know the exposure limit that applies where they work, control silica dust, and train the workers who may be exposed. Keeping dust out of the air, checking that controls work, and reinforcing safe work practices help protect workers from long-term harm. 4,28,7