Crystalline Silica: The “Asbestos” of the 21st Century?

Lisa Scolaro, B.Sc., ROH, CRSP, CHSC | June 2023


Did you know that silica is one of the most common hazards in the workplace in Ontario? CAREX Canada estimates that 142,000 Ontarians are exposed to silica in their workplace daily! Silica has been called by some the “asbestos of the 21st century”, but why exactly is that? What’s so dangerous about silica?

So, what is silica?

Silica is actually one of the most common minerals found in the crust of the earth. There are two forms of silica: crystalline and non-crystalline or amorphous.


Crystalline silica is the type of silica that has negative impacts on health. It is formed from amorphous silica by high pressure or heat. The most common type of crystalline silica is quartz, which is naturally found in sand, gravel, clay, granite, diatomaceous earth, and many other rock forms. Small particles of crystalline silica are released in dust form through processes such as blasting, cutting, drilling, or grinding materials that contain silica. A wide range of construction materials contain crystalline silica and include (but are not limited to):

  • Bricks
  • Concrete blocks
  • Gravel
  • Stone
  • Concrete
  • Mortar
  • Glass
  • Ceramics
  • Artificial (or ‘engineered’) stone countertops
  • Granite
  • Some types of fiberglass
  • And more…

The highest risks of exposure are found in the construction, mining, oil and gas, manufacturing, and agricultural sectors, but exposure can occur anywhere where any silica-containing material is cut, drilled, grinded or blasted without proper precautions in place.

Why is silica a health hazard?


Breathing in small crystalline silica particles can increase your risk of developing silicosis, a serious and irreversible lung disease (not dissimilar to asbestos-caused asbestosis). Crystalline silica particles range in size from approximately 0.01 to 100 micrometres in diameter. To put this into perspective, the average human hair is approximately 100 micrometres in diameter.

When inhaled, silica particles become trapped in the lung tissue, causing inflammation and scarring and reducing the ability of the lung to take in oxygen. The damage caused to the lung is permanent and debilitating. The resulting health impacts include a chronic cough, shortness of breath, fatigue and chest pain.

Typically, silicosis occurs after 10 or more years of exposure to respirable crystalline silica; however, heavy exposure can result in the development of silicosis much quicker. Silica can exposure further puts workers at a risk for developing several other serious disease such as lung cancer, chronic obstructive pulmonary disease (COPD), kidney failure, autoimmune diseases, and increased susceptibility to tuberculosis, to name a few.


In Ontario alone, 2.5% of lung cancers that are diagnosed each year are caused by silica exposure.

Why is Crystalline Silica called the “Asbestos of the 21st Century”?

In its original form, asbestos is actually a naturally occurring fibrous silicate mineral. As such, asbestos is really a form of a silicate material, in the same way that silica dust is. Even though they have similarities in their composition and the target organ in the human body, there still continues to be differences in attitudes towards asbestos and silica.

The hazards of asbestos are now well detailed in the media, the asbestos abatement industry, and reflected in numerous laws worldwide. Yet the process of hazard recognition, documentation and legislation took time. It wasn’t until decades after exposing workers to asbestos that we began to see the devastating long term health effects of asbestos exposure. While the appropriately stringent guidelines were eventually put in place regarding asbestos exposure, sadly, much of it was after the fact and the damage had been done. Now, there is a lot more awareness and caution around asbestos exposure, but are you as aware of the hazards and precautions needed around crystalline silice?

Despite similar health hazards, the dangers of crystalline silica exposure are not fully communicated and widespread…yet. Over the last decade, as more people are diagnosed with silicosis, there has been a large push amongst both industry and regulating bodies to put into place the necessary framework to bring awareness to silica exposure and protect from its harmful effects.

What are my requirements as an employer?

Silica is identified as a designated substance under Ontario Regulation 490/09. Ontario Regulation 490/09 applies “to every employer and worker at a workplace where silica is present, produced, processed, used, handled or stored and at which a worker is likely to be exposed to silica”. A key element of this regulation requires the completion of an assessment to determine the potential for, and likelihood of, worker exposure to crystalline silica. Where there is a potential for any exposure to respirable crystalline silica, a control program is required. A control program will include:

  • Controls for limiting worker exposure,
  • Methods for testing airborne concentrations,
  • Worker training, and
  • Retention of records related to the control program.

If your workers cut, drill, grind, blast or otherwise disturb crystalline silica-containing materials,
your workplace needs a silica control program.

How do I protect myself or my employees from silica exposure?

The best way that you can protect yourself or others is to eliminate any sources of silica dust exposure. Recognizing that this is not possible in many of the industries where silica is present, risk controls can be put into place. Controlling the risk of exposure can include such measures as:

  • Local exhaust ventilation,
  • Utilizing water to prevent dust from becoming airborne, or
  • Enclosing areas where dust is generated.

Administrative controls, such as exposure control plans, warning signs, safe work procedures and movement of employees away from areas where silica dust is generated are also effective. As a last line of defence, and in conjunction with other controls, personal protective equipment, including respirators, can also be utilized by workers who have received respirator training and fit testing.

What are the next steps?

Across the globe, the recognition of the hazards of silica are mounting. Numerous regulatory bodies and private organizations are looking at positive changes to reduce worker exposure to silica:

  • In conjunction with both federal, state and territory governments, Safe Work Australia is currently reviewing existing regulations and discussing new regulations which ban engineered stone. The Australian National Construction Union has also called for a ban on engineered stone by July 1, 2024.
  • The U.S. Department of Labour’s Mine Safety and Health Administration has recently launched a new enforcement initiative to protect workers from repeated exposure to respirable crystalline silica. This initiative includes increased inspections and sampling at coal and non-metal mines, increase enforcement for known silica hazards and an uptick in training for miners regarding their rights.
  • Throughout 2022, the Ontario Ministry of Labour, Immigration, Training and Skills Development (MLITSD) conducted a compliance initiative which included workplace inspections to ensure that employers were taking action to assess and address crystalline silica exposure. Moving in to 2023, the MLITSD continues with inspections as they relate to respiratory protection programs.

Can ECOH help me?

Absolutely! Our Occupational Health and Safety team can help you complete an assessment for crystalline silica exposure, complete air sampling, design a control program, provide respirator fit testing and train your workers. Get in touch today and we can help you protect your workers and stay in compliance.

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