Definitions and Regulations
Respirable Crystalline Silica (RCS) Definition
Section 6.110 of the OHS Regulation defines RCS dust as any of the following that can be deposited in the lower gas exchange regions of the lung when inhaled:
- Respirable crystalline silica
- Respirable α-quartz
- Respirable cristobalite
Section 6.110 of the OHS Regulation defines silica processes as any process that may result in the release of RCS dust in concentrations likely to exceed the exposure limit, including:
- Cleaning of castings
- Abrasive blasting, grinding, sanding, or dressing of any surface that contains crystalline silica
- Blasting, cutting, crushing, drilling, grinding, milling, scaling, splitting or sieving, or other mechanical pulverizing or shattering, of rock, siliceous stone, or gravel
- Concrete or asphalt milling, shotcreting, pneumatic drilling, tunnelling, or other large-scale mechanical processes that may generate RCS dust
- Using heavy equipment or pneumatics to transfer sand, earth, aggregate, or other material that contains silica, and associated transport, recycling, and disposal operations
- A process in which silica flour is used, including using it as an additive in product manufacturing
- Manufacturing, dismantling, demolishing, or repairing of concrete, masonry, or other material that contains silica
- Using power tools or equipment to abrade, cut, grind, core, or drill concrete, masonry, or other material that contains silica
Air Monitoring for RCS Dust
WorkSafeBC-approved sampling methods include appropriate methods published by NIOSH or OSHA. In addition to WorkSafeBC-approved methods, the Airport Authority requires all samples to be sent to labs that are CALA or AIHA participants, and/or NVLAP accredited.
WorkSafeBC Occupational Exposure Limit
OHS Regulation Part 5 G5.48-1, Exposure Limits – Tables, shows the current 8-hour time weighted average (TWA) for crystalline silica to be 0.025 mg/m3.
RCS dust can be released into the air as a fine dust during activities such as sanding, cutting, drilling, grinding, crushing, demolition, and cleanup of silica-based materials.
A risk assessment must be completed for every work task, taking into account the amount of silica in the material, type of work, and potential for exposure to RCS dust.
As silica is classified by WorkSafeBC as an ALARA substance, Exposure Control Plans must be developed based on the risk assessment, and dust controls must be in place.
Airport Authority Minimum Control Expectations
The Airport Authority has minimum expectations that must be met when there is a potential for hazardous exposure to RCS dust.
- Avoid the use of products or materials containing crystalline silica.
- If it is not practicable to eliminate the risk of worker exposure to RCS dust, control the risk below the applicable exposure limit by applying control measures that include the following, in this order:
- Engineering controls:
- Appropriate dust reduction systems
- Containment of silica processes, and
- Provision and use of suitable work equipment and materials
- Administrative controls:
- Safe Work Procedures
- Personal protective equipment:
- Minimum half-mask respirators
- Engineering controls:
- Air monitoring:
- If there is no historical, peer-reviewed, or research data indicating that exposure to silica is below the occupational exposure limit for a similar task, conduct occupational air monitoring during the first shift and as necessary throughout the work activity or silica process to ensure that control measures are effective.
- Keep, for at least 10 years, records of the results of air monitoring.
- At the end of every shift, if practicable, clean all workplaces and work-related areas and equipment where RCS dust may accumulate using one or a combination of the following:
- Vacuum or similar device
- Wet cleanup methods
- Another method that is effective and in compliance with the safe work practices in the Exposure Control Plan
- If a vacuum or similar device is used, the vacuum or device must be:
- Designed for the task
- Maintained, tested, and used as specified by the manufacturer
- Equipped with an effective HEPA filter on the exhaust
- When a HEPA vacuum is not being used for cleanup, use wet cleanup methods. When the work is completed, any slurry generated by wet cleanup methods must be removed in a manner that avoids a secondary RCS dust exposure.
- Place waste in sealable containers and promptly dispose of it to prevent RCS dust from re-entering the workplace.
- Do not use blowers, compressed air, dry sweeping, or dry mopping to clean up or remove RCS dust.
- Any worker who is or may be exposed to RCS dust must have education and training on the following:
- Hazards and health effects of inhaling RCS dust
- Safe work practices and procedures
- Correct operation and use of any required equipment and engineering controls
- Purpose and limitations of PPE, and correct selection, fitting, use, care, and maintenance of that equipment
- Housekeeping practices