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Crystalline silica

Regulatory amendments

Since June 8, 2023, regulatory changes to the Safety Code for the construction industry have been in force. For more information on these changes, consult subdivision 3.25 of the Safety Code for the construction industry.

In addition, new permissible exposure values to prevent exposure to crystalline silica have come into force on April 28, 2024. For example, the permissible value for the quartz form of crystalline silica have been reduced to 0.05 mg/m3. For more information, consult the regulation published in the Gazette officielle du Québec.

Quartz is the most common form of crystalline silica. Quartz is found in brick, mortar, concrete, ceramics, foundry sand and granite. Activities such as demolition, crushing, drilling, sawing, grinding, sanding and dry sweeping materials containing crystalline silica expose workers to crystalline silica dust.

Exposure to crystalline silica dust can cause silicosis, which is characterized by respiratory difficulties ranging from shortness of breath on exertion to severe respiratory failure. It can also lead to asthma, emphysema and lung cancer, among others.

The employer is responsible for implementing measures to control crystalline silica emissions at source to reduce them to a minimum. Where necessary, they must provide respiratory protective equipment (RPE) (in French only), put a respiratory protection program in place and train workers on the wearing, care and storage of RPE. RPE must be certified by the National Institute for Occupational Safety and Health (NIOSH).

For their part, workers must wear the RPE provided by the employer and use the controls at source that have been put in place.

Safety rules

 Zero tolerance 

If any of the rules mentioned below are not followed, the CNESST will stop the work and those at fault will be liable to criminal prosecution.

For more information, see the Zero tolerance – Crystalline silica sheet (in French only).

Specific measures to be applied in construction

To reduce exposure to crystalline silica dust when carrying out certain activities, the employer must put dust control measures in place, provide workers with appropriate RPE and make sure they wear it.

Activities targeted by this rule

Targeted activities on a construction site are sawing, jackhammering, confined drilling, grinding, sanding, roughening and drilling.

Specific requirements apply during abrasive blasting work.

Specific measures that must be applied in establishments

To reduce exposure to crystalline silica dust, the employer must put controls in place, provide workers with appropriate RPE when required and make sure they wear it. Workers are required to wear RPE when the permissible exposure values provided for in Schedule 1 of the Regulation respecting occupational health and safety (ROHS) are exceeded.

Activities targeted by this rule

Targeted activities in establishments are activities that can expose workers to higher than standard concentrations of respirable crystalline silica, such as polishing, manual cutting, cutting and crushing.

Specific requirements apply during abrasive blasting work.

Other mandatory preventive measures

Depending on the tasks to be carried out, one or more of the following measures must be taken by the employer to control the risks associated with crystalline silica: Note that the sections of the SCCI apply only to work carried out on a construction site. The sections of the ROHS that also apply to construction sites are clearly indicated below.

  • Implement or improve the effectiveness of measures to control crystalline silica emissions at source. For example:
  • Develop and implement a respiratory protection program and train workers on the wearing, care and storage of RPE
  • Train and inform workers on the risks associated with exposure to crystalline silica, prevention methods and safe working methods
  • Make sure that the equipment used to prevent silica dust emissions is in working order and operating optimally during operating hours
  • Operate and maintain equipment to control dust in accordance with the manufacturer’s instructions
  • Inspect mechanical ventilation systems at least once a year
  • Delimit the work area where workers are required to wear RPE and limit access to the workers who are carrying out the work and who are wearing appropriate RPE
  • Ensure that a worker who carries out work that requires RPE to be worn takes off their work clothes or cleans them using appropriate methods before leaving the work area and removing their RPE
  • When cleaning the work area, do not use methods that cause dust to become suspended in the air
  • Wet debris from materials presumed to contain or containing crystalline silica or use an equivalent means to prevent them from being dispersed
  • Ensure proper maintenance of the premises by limiting dust
  • Where possible, replace silica containing materials with silica free materials or materials that contain less silica

Protective measures

Laws and regulations