SILICA IN THE WORKPLACE
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About this Guide
Silica, meaning crystalline silica in the respirable form, is a designated substance under the Occupational
Health and Safety Act (OHSA), and the subject of the Ontario Regulation O. Reg. 490/09: Designated
Substances made under the OHSA. This Regulation applies to workplaces in which silica is present,
produced, processed, used, handled or stored. It establishes the time-weighted average exposure to silica
in a typical 8 hour work day or 40 hour work week and also provides calculations of the TWA exposure
for extended work shifts. The law provides for assessment of worker exposure, and for implementing a
control program, should certain conditions be met.
The purpose of this guide is to provide general information about silica to employees, members of joint
health and safety committees, supervisors, and managers. The guide outlines uses and health effects
of silica, and provides guidelines for setting up a program to determine and control workplace exposures.
To make best use of this guide you may wish to find out how much you know already about silica and
its hazards. The following questions were prepared to help you. We suggest that you try to answer them
before reading further. The answers are found inside.
1. Which forms of silica pose a hazard in the workplace?
2. How can you determine whether a hazardous form of silica is present?
3. Does all dust containing a hazardous form of silica pose the same hazard? Explain.
4. Does the potential for inhaling a hazardous form of silica exist in your job?
5. How do the hazardous forms of silica affect the body?
6. How can a doctor identify a silica-related disease?
7. How can silica exposure in the workplace be controlled?
8. Describe the silica control program that is in effect at your workplace?
9. What is the importance of a medical surveillance program?
