January 10, 2019
Your health, your company —  and silica dust

Your health, your company — and silica dust

Why dust is such a serious health hazard, and what you can do about it.


Dust is a reality for anyone in landscape construction. When you inhale dust from cutting or grinding concrete, mixing materials, dry sweeping or demolition, tiny quartz/silica particles penetrate deep into the lungs and cause scarring and disease.

The risks are so serious, regulations have been put in place for Canada by the Canadian Centre for Occupational Health and Safety (CCOHS) and for the U.S. by Occupational Safety and Health Administration (OSHA), to create awareness and manage this risk at worksites. The goal is to create safer work environments with reduced health risks for you, your employees and anyone exposed to construction dust. 

man cutting a stone paver with a stone sawDry cutting with a dust shroud to contain the silica dust.

Know the hazard

Crystalline silica is an extremely common mineral found in sand, stone, and concrete that becomes dangerous when disturbed. Cutting, crushing, grinding, or drilling of stone, brick or concrete generates a fine silica dust that, unless contained, will seriously contaminate the air. Inhaled silica dust causes fibrosis or scar tissue, as well as silicosis lung disease, both of which reduce the lungs’ ability to extract oxygen from the air. There is no cure for these often-fatal diseases.

Know the standard 

In Canada, the CCOHS is a great place to start for information. There are 14 jurisdictions that have their own Occupational Health and Safety legislation, including occupational silica exposure limits. You can find the exposure limits and links to the legislation for each province in the online version of this article at www.landscapetrades.com/silica.

In Ontario, for example, the legislation does more than specify exposure limits. It also requires employers to take steps to protect employees from the hazard and defines employer responsibilities if exposure takes place

In the U.S., the OSHA Silica Standard, implemented in 2016, limits silica exposure to a Permissible Exposure Limit (PEL) of 50 micrograms of respirable crystalline silica per cubic metre of air or 50 µg SiO2/m³ over an eight-hour time weighted average (TWA). OSHA recognizes using tools equipped with a water delivery system that supplies a continuous stream or spray of water at the point of impact, or using tools equipped with a commercially available shroud and dust collection system, as control methods that safely limit silica exposure.  man wearing a mask using a plate compactor on a driveway with lots of dustCutting, grinding, or drilling of hardscape materials generates a fine silica dust that contaminates the air.
Generally, Canadian regulations are comparable to U.S. regulations. However, violations in the U.S. are expensive; fines of over $7,500 per person are given for breach of the Silica Regulation. With the importance given to the silica issue in the U.S., we are likely to see similar enforcement and fines in Canada in the near future.

Know your exposure 

One way to determine silica exposure is through air monitoring. This may seem like a complicated, expensive process; however, it’s fairly easy once you understand what is involved.

Air monitoring equipment measures the air quality in a worker’s breathing area to determine silica exposure during a specific work practice. Air monitoring uses a battery-operated vacuum attached to an operator’s shirt collar, collecting air samples right where the operator breathes. Once you learn your exposure levels, you can decide what options are best suited to control silica exposure on your job sites.

Another way to determine silica exposure is by using objective data provided by tool manufacturers. In the U.S., OSHA defines Objective Data as “information, such as air monitoring data, from industry-wide surveys or calculations based on the composition of a substance, demonstrating employee exposure to respirable crystalline silica associated with a particular product or material or a specific process, task, or activity. The data must reflect workplace conditions closely resembling or with a higher exposure potential than the processes, types of material, control methods, work practices, and environmental conditions in the employer’s current operations.” When a manufacturer tests its equipment, if the work practice and materials used match job site conditions, OSHA allows this data to be used as objective data as part of a written silica exposure control plan (https://plan.silica-safe.org).

chart showing the various levels of silica exposureSafe and hazardous occupational silica exposure levels.
The PEL requires employers to limit worker exposures to respirable crystalline silica and take other steps to protect employees. Regardless of exposure control methods used, you should implement a Silica Safety Program including the following elements:
  • Hazard identification, assessment and solutions.
  • Trained staff member for implementation and monitoring.
  • Offer of medical exams.
  • Documented training.
  • Record keeping.
A detailed list of control plan components is posted in the online version of this story, www.landscapetrades.com/silica.

In my experience, the key to protecting yourself and your employees is to take responsibility and implement systems. Just because a tool is CCOHS Compliant, it does not automatically mean the company using the tool is compliant with the regulation.

Know your options 

The construction industry and associated technologies are rapidly changing. Wet cutting and dry cutting without a vacuum have been the main applications for cutting concrete, asphalt and masonry materials for decades. Three main dust control strategies are available to today’s contractors:
  • Wet cutting. 
  • Dry cutting with a dust shroud.
  • Dry cutting with integrated dust collection. 
Wet cutting works well when you have a cutting station, but it can be very messy and can create problems like water damage to the base and/or bedding sand layer (if cutting pavers or walls in place), and staining with the wet dust sticking to the paver surface. Dustless vacuum systems and dust collecting systems vary in efficiency and effectiveness, but integrated systems can capture over 99 per cent of particulates.

close up of a table mounted wet stone saw cutting paverWet cutting is a good choice when a cutting station is available, but can be a messy alternative without.
No matter what tool you’re using, it’s essential to wear personal protective equipment such as eyewear and ear attenuators. Know exactly what you’re cutting so you can implement proper control methods. Following a control hierarchy, listed below from most to least efficient, is the best way to control dust hazards:
  • Elimination: Physically remove the hazard.
  • Substitution: Replace the hazard.
  • Engineering controls: Isolate people from the hazard.
  • Administrative controls: Change the way people work.
  • Personal protective equipment: Least efficient, but mandatory.

Silica summary

Know the hazard Understand the hazard and risks associated with silica exposure.
Know the standard Understand the CCOHS Permissible Exposure Limit and what it means to you, your business and your workers.
Know your exposure Understand how to use air monitoring to measure silica exposure levels — and understand the results.
Know your options Understand your options, including tools, work practices and educational resources for controlling silica exposure on your job sites.
Jurisdiction Regulation 8 Hour Exposure Limit
Federal Canada Occupational Health and Safety Regulations Use ACGIH TLVs
Quartz and Cristobalite (respirable): 0.025 mg/m3
British Columbia Occupational Health and Safety Regulation
Part 5 Chemical Agents and Biological Agents
Quartz and Cristobalite (respirable): 0.025 mg/m3
Alberta Occupational Health and Safety Code 2009
Part 4 Chemical Hazards, Biological Hazards and Harmful Substances
Cristabolite (respirable): 0.025 mg/m3
Quartz (respirable): 0.025 mg/m3
Saskatchewan The Occupational Health and Safety Regulations, 1996
Cristobalite (respirable): 0.05 mg/m3
Quartz (respirable fraction): 0.05 mg/m3
Tripoli, as quartz (respirable): 0.1 mg/m3
Manitoba Occupational Health and Safety Regulation Use ACGIH TLVs
Quartz and Cristobalite (respirable): 0.025 mg/m3
Ontario Regulation 833: Control of Exposure to Biological or Chemical Agents Quartz/Tripoli (respirable): 0.10 mg/m3
Cristobalite (respirable): 0.05 mg/m3
Quebec Regulation respecting occupational health and safety Cristobalite: 0.05 mg/m3               
Quartz: 0.1 mg/m3
Tridymite: 0.05 mg/m3
Tripoli: 0.1 mg/m3
New Brunswick General Regulation Use ACGIH TLVs
Quartz and Cristobalite (respirable): 0.025 mg/m3
Nova Scotia Workplace Health and Safety Regulations Use ACGIH TLVs
Quartz and Cristobalite (respirable): 0.025 mg/m3
Newfoundland and Labrador Occupational Health and Safety Regulations, 2012 Use ACGIH TLVs
Quartz and Cristobalite (respirable): 0.025 mg/m3
Prince Edward Island General Regulations Use ACGIH TLVs
Quartz and Cristobalite (respirable): 0.025 mg/m3
Northwest Territories Occupational Health and Safety Regulations Cristobalite (respirable): 0.05 mg/m3
Quartz (respirable): 0.05 mg/m3
Tripoli, as quartz: 0.1 mg/m3
Nunavut Consolidation of Occupational Health and Safety Regulations Cristobalite (respirable) : 0.05 mg/m3
Quartz (respirable): 0.05 mg/m3
Tripoli, as quartz: 0.1 mg/m3
Yukon Occupational Health Regulation Quartz: 300 particles/mL
Cristobalite: 150 particles/mL
Tridymite: 150 particles/mL

Frank Bourque is a speaker, writer, consultant, entrepreneur and Interlocking Concrete Pavement Institute instructor who coaches hardscape pros across North America. Thanks to iQ Power Tools and Hulton Tool for photos and information used in this article.