Silica - Approval of Quebec Model for Work Shifts Longer Than 8 Hours

Occupational health and safety is a paramount concern for any society, as it directly impacts the well-being of workers across various industries. Alberta, Canada, has taken a significant step in ensuring worker safety by granting approval for the use of the Quebec model to adjust Occupational Exposure Limits (OELs) for the substance of respirable crystalline silica during work shifts longer than 8 hours. This blog post delves into the details of this approval, the significance of the Quebec model, and the implications it holds for employers and workers in Alberta.

The approval is subject to certain terms and conditions to ensure its effective implementation. Employers must either use Alberta's Occupational Exposure Limit for respirable crystalline silica when applying the Quebec model (complex method) or use the adjusted Occupational Exposure Limits specified in the approval (simple method). The simple method provides exposure limits based on different average work hours per week, allowing employers to apply the most appropriate limit based on their specific schedules.
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Background on Occupational Health and Safety Act

The Occupational Health and Safety Act (OHSA) plays a crucial role in safeguarding workers' health and safety in Alberta. Under subsection 22(1) of the OHSA, a Director has the authority to issue approvals to individuals, provided they meet certain terms and conditions, to maintain the health and safety of all involved parties. Furthermore, under subsection 22(3), the Director has the power to impose additional terms and conditions on such approvals.
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IRSST - Quebec Model

The Occupational Health and Safety Code includes provisions for adjusting Occupational Exposure Limits for substances when work shifts exceed 8 hours. The Quebec model, developed and published by the Institut de recherche Robert-Sauvé en santé et en sécurité du travail (IRSST) du Quebec, is a recognized scientific method that uses the Haber method to calculate adjusted exposure limits.
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This model holds significant importance as it aligns with the Threshold Limit Values (TLVs) for chemical substances published by the American Conference of Governmental Industrial Hygienists. Moreover, Alberta's Occupational Exposure Limits for chemical substances are largely based on the TLVs, further highlighting the relevance of the Quebec model for the region.
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Approval of Quebec Model for Respirable Crystalline Silica

In a groundbreaking move to enhance worker safety, Mark Rice, a designated Director under the OHSA, has granted approval for the use of the Quebec model to adjust the Occupational Exposure Limit for respirable crystalline silica. Respirable crystalline silica, with CAS numbers 14464-46-1 and 14808-60-7, is a substance that poses health risks to workers, especially during extended work shifts.
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New Occupational Exposure Limits for respirable crystalline silica

The following adjusted Occupational Exposure Limits for respirable
crystalline silica (based on applying the Quebec model) (“simple method”),

• 0.025 mg/m3 for work schedules averaging less than 40 hours per week (e.g., three 12-hour shifts followed by four days of rest),
• 0.025 mg/m3 for work schedules averaging 40 hours per week (e.g., four 10-hour shifts followed by three days of rest),
• 0.024 mg/m3 for work schedules averaging 42 hours per week (e.g., seven 12-hour shifts followed by seven days of rest, or fourteen 12-hour shifts followed by fourteen days of rest),
• 0.021 mg/m3 for work schedules averaging 48 hours per week (e.g., six 8-hour shifts followed by one day of rest or four 12-hour shifts followed by three days of rest),
• 0.020 mg/m3 for work schedules averaging 50 hours per week (e.g., five 10-hour shifts followed by two days of rest),
• 0.017 mg/m3 for work schedules averaging 60 hours per week (e.g., six 10-hour shifts followed by one day of rest, twelve 10-hour shifts followed by two days of rest, five 12-hour shifts followed by two days of rest, or ten 12-hour shifts followed by four days of rest),
• 0.014 mg/m3 for work schedules averaging 72 hours per week (e.g., six 12-hour shifts followed by one day of rest, twelve 12-hour shifts followed by two days of rest, or twenty-four 12-hour shifts followed by four days of rest), or
• the lower of the two Occupational Exposure Limits specified in this list if the average hours in a work schedule falls between two adjacent items in this list.

Effective Date

This approval comes into effect on July 12, 2023. This approval shall be effective for a
period of ten (10) years from the effective date, unless varied, suspended or revoked under subsection 22(6) of the Occupational Health and Safety Act.

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How Can an Industrial Hygienist Help?

An industrial hygienist plays a crucial role in ensuring the health and safety of workers in industrial settings. Their expertise lies in identifying and controlling workplace hazards that could adversely affect the health and well-being of employees. Here are some ways in which an industrial hygienist can help:

1. Hazard Identification: Industrial hygienists conduct thorough assessments of the workplace to identify potential hazards such as chemical exposures, dust, noise, ergonomic issues, and biological agents. They use various monitoring and sampling techniques to measure the levels of contaminants in the air, soil, or water.
   
2. Risk Assessment: After identifying hazards, industrial hygienists evaluate the risks associated with exposure to these hazards. They analyze exposure levels, review health effects data, and determine if workers are at risk of injury or illness. Based on the assessment, they propose appropriate control measures.
   
3. Exposure Control: Industrial hygienists develop and implement control strategies to minimize or eliminate exposure to workplace hazards. These controls may include engineering solutions (e.g., ventilation, enclosure), administrative controls (e.g., work schedules, training), and personal protective equipment (PPE).