Occupational Hygiene

Health & Safety Regulations in Ontario

In Ontario, the health and safety of workers is protected under several regulations made under the Occupational Health & Safety Act (OHSA).  This Act applies to almost every worker, supervisor, employer and workplace in Ontario that is not federally regulated.  Specific regulations made under the Act apply primarily to work environments such as industrial and manufacturing facilities and construction sites.  Key safety regulations include Regulation 851 “Industrial Establishments” and Regulation 213/91 “Construction Projects”.  These regulations primarily govern safety aspects for workplaces including requirements for providing proper guarding on machinery, fire prevention, material handling, and protective equipment, and proper use of ladders, scaffolds, etc.  Regulation 213/91 provides additional safety requirements for working in specific construction environments such as tunnels, excavations, or compressed air environments.

One of the primary regulations protecting the health of workers from exposure to airborne contaminants in Ontario workplaces is Regulation 833 “Control of Exposure to Biological or Chemical Agents”.  This regulation requires employers to protect workers from exposure to hazardous biological or chemical agents by restricting the amount and duration of exposure to over 700 hazardous substances.  Airborne exposure limits provided in Regulation 833 are known as Occupational Exposure Limits (OELs) and can come in the form of Time-Weighted Average Exposure Values (TWAEVs), Short-Term Exposure Values (STEVs) and Ceiling Exposure Values (CEVs), depending on whether the airborne limit is averaged over 8-hours, 15-minutes, or is a concentrations that should never be exceeded at any point in time.  The concentrations and averaging times listed in Regulation 833 have been set at levels that are expected to protect the majority of workers from the onset of specific adverse health effects (even with repeated daily exposures) and have been established based on the best scientific and medical evidence available.  This regulation requires employers to take measures to ensure that the airborne concentrations of contaminants remains below their respective OELs through the use of engineering controls, work practices, and if necessary, personal protective equipment.

In addition to Regulation 833 there are eleven individual contaminants in Ontario that have regulations applicable specifically for that one particular substance.  These contaminants are referred to as Designated Substances and include acrylonitrile, arsenic, asbestos, benzene, coke oven emissions, ethylene oxide, isocyanates, lead, mercury, silica and vinyl chloride.  Specific regulations were developed for these compounds due to their well documented, severe health effects that overexposure may pose.  The designated substances regulations not only provide regulated airborne exposure limits for each contaminant but also include additional requirements such as the completion of a hazard assessment and implementation of a control program when it is determined that a worker is likely to be exposed to the substance.  Components of control programs include measures that are to be taken to protect workers from exposure to the designated substance and procedures to monitor exposure and worker health.  Every control program includes provisions for engineering controls, work practices, and hygiene practices and facilities to control worker exposure to the substance and also includes provisions for monitoring worker exposure, record keeping and medical monitoring.

In order to ensure that workers are aware of and familiar with all potential hazardous aspects of products that they work with or are in proximity to, the Workplace Hazardous Materials Information System (WHMIS) was developed. WHMIS is a national system with consistent requirements across the country.  It requires suppliers of hazardous materials to provide information on those hazards to their customers, and requires employers to provide this information to workers with labels, Material Safety Data Sheets (MSDS), and worker education.  In Ontario, Regulation 860, “Workplace Hazardous Materials Information System (WHMIS)” regulates WHMIS.

For substances where no airborne exposure limits exist, the OHSA still requires employers of workplaces using any substance not covered by one of the above regulations to take reasonable precautions in the circumstances to protect the worker.  This clause in the OHSA is known as the general duty clause.