This talk from Melanie Gorman Ng gave key insights into practical tools for silica exposure reduction in workplaces.

1. EXPOSURE REDUCTION FOR
SILICA IN CONSTRUCTION
WORKPLACES
Melanie Gorman Ng
School of Population and Public Health, UBC
Nov 7th 2017

2. The Silica Control Tool
A risk assessment and educational tool for the
construction industry.

3. Silica in Construction
573
lung cancers

4. Silica in Construction

5. Silica in Construction
§ 380 000 Canadians
exposed
§ 56% in construction
§ 200 000 construction
workers exposed

6. Construction Industry Challenges
• Work sites change rapidly
• Workers and companies move between sites
• Tasks vary within and between work shifts
• ~95% of BC employers are SMEs (small and medium employers)
• Lack of exposure measurement data and hygiene expertize

7. Substance specific requirements for silica.
■ Requirement to monitor exposure for any “work activity
that generates RCS dust” and create Exposure Control
Plan
■ Monitoring can be based on “objective monitoring data,
that was collected during equivalent work operations
through industry surveys or peer-reviewed or scientific
studies…”
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Regulation Change

8. An On-Line Silica “Tool”
■ BCCSA partnership with UBC and WorkSafeBC
■ Help employers effectively use “Equivalent Work Operations”
clause
■ Educate employers
■ Reduce effort and cost
■ Improve quality of exposure data
■ Help produce effective ECP’s

9. Benefits of Quantitative Approach
■ Employers/employees become more knowledgeable
– See and compare objective evidence of
exposure, and control effectiveness
■ Monitor trends in exposures
– Provides benchmark data
■ Compare control options – identify “best practices”
■ More easily calibrated to other jurisdictions
■ Promote data sharing
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10. Silica in Construction Database
■ Database of silica in construction measurements compiled
by Beaudry et al. (2013)*: N = 11 845
■ Updated literature review in 2015: N = 3 653
■ Canadian companies and govt.: N = 294
■ Monitoring at BC worksites in 2015: N = 318
www.skcinc.com
*Beaudry C, Lavoué J, Suavé J-F et al (2013). Occupational
Exposure to Silica in Construction Workers: A Literature-Based
Exposure Database. J Occup Environ Hyg; 10(2):71-77.

11. Exposure Modelling
Restricted database to:
■ Personal samples
■ Chemical analysis for RCS (quartz or cristobalite)
■ Standardized sampling/analytical methods
N = 4550

12. Exposure Modelling
Linear Regression Model with Exposure Level as outcome variable
■ Sampling Duration
■ Silica Process (combines task, tool and material variables)
■ Engineering Controls
– LEV
– LEV integrated with tool
– Material wetting
– Water spray integrated with Tool
■ Industry Sector
■ Project type (new vs. renovation or demolition)
■ Work Environment (indoor or outdoor)
■ Region

13. Variability Simulation
§ Tool presents 95th percentile exposure estimate
§ Randomly generate 1000 values for each variable
(coefficient =GM, standard error = GSD)
§ Use simulated values to generate 1000 exposure estimates
§ Use 1000 exposure estimates to estimate 95th percentile

14. Tool Demonstration

27. Usage Statistics – As of Nov 3rd
■ 642 User Accounts
■ 1707 ECP project
■ New regulations took effect May 2017
- 476 new user accounts
- 1578 ECP projects

28. Continued Developments
■ BC Sampling– additional scenarios, refinement, temporal changes
■ Tool V2 released October 2017

29. Continued Development
■ Alberta OHS Futures –
– validation
– extension to another jurisdiction
■ Manitoba study
– extension to another jurisdiction
– refinement of modelling approach (bayesian framework)

30. Conclusions
• Project encourages exposure measurement and sharing by
employers (further development of database)
• Data can be used beyond one-time compliance measure
• Aim to update model and tool as new data become
available
• Working on bringing approach to other jurisdictions

31. Acknowledgments
■ Hugh Davies, UBC
■ Project Steering Committee:
– Nancy Harwood (Project Manager, Lawyer)
– Mike McKenna (Executive Director, BCCSA)
– Colin Murray (WorksafeBC)
– Don Schouten (WorksafeBC)
■ Jérôme Lavoué, Université de Montréal
■ Kelly Stuart, BCCSA
■ Mili Baghela, Marybeth MacDonald, Brendan Talbot
■ Funding – BCCSA, Alberta OHS Futures
■ Cooperation of many construction industry companies
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