Background

O. Reg. 490/09 – Designated Substances (referred to as the regulation or O. Reg. 490/09 throughout the guide) is one of three main regulations under the Occupational Health and Safety Act (OHSA) addressing worker exposure to hazardous chemical and biological agents.

The other two regulations are:

Another related regulation under the OHSA is regulation 860 – Workplace Hazardous Materials Information System (WHMIS). WHMIS provides employers and workers information about hazardous materials used in the workplace.

O. Reg. 490/09 prescribes 11 chemical agents as designated substances under OHSA. They are: acrylonitrile, arsenic, asbestos, benzene, coke oven emissions, ethylene oxide, isocyanates, lead, mercury, silica and vinyl chloride. Definitions for some of these chemicals can be found in O. Reg. 490/09.

O. Reg 490/09 is the primary regulation addressing occupational exposures to the designated substances. Notable exceptions include exposures to asbestos addressed under O. Reg. 278/05 and exposures to these substances in workplaces not subject to O. Reg. 490/09, which are addressed under regulation 833.

In addition to setting occupational exposure limits (OELs), key features of O. Reg. 490/09 include workplace assessments, the engagement of joint health and safety committees (JHSCs) and the establishment of control programs addressing control measures (for example, engineering controls, work practices and hygiene facilities and practices), air monitoring, worker and supervisor training, medical surveillance examinations and record keeping.

2020 updates

Effective January 1, 2020, the respiratory, measuring and medical surveillance provisions in O. Reg. 490/09 were updated, streamlined and replaced. These changes are described in this guide.

Key changes include:

  • updating, consolidating and replacing the medical surveillance codes for nine designated substances with a new Code for Medical Surveillance for Designated Substances*
  • replacing 16 outdated Codes for Respiratory Equipment and Measuring Airborne Substances with new, updated respirator and air monitoring provisions**
  • amending the scope of an employer’s duty under section 15 to address the exposure of third party workers engaged in construction to designated substances depending on the circumstances
  • providing for the use of an OEL adjustment method used in Quebec that takes into consideration an agent’s health effects when determining exposures for extended work shifts

*The new Code for Medical Surveillance for Designated Substances applies to employers that are required to provide for medical examinations under subsection 20(4) of O. Reg. 490/09. It sets out the medical surveillance program requirements for asbestos, benzene, coke oven emissions, isocyanates, lead (inorganic and organic), mercury (alkyl and non-alkyl compounds) and silica.

**The new respirator and compressed breathing air requirements are aligned with, and in some cases expressly reference, sections of CSA Standard CAN/CSA-Z180.1-13 (R2018), Compressed Breathing Air and Systems (2018) or CSA Standard CAN/CSA-Z94.4 -18, Selection, Use and Care of Respirators (September 2018). These standards may be viewed on the ministry’s website for free or purchased from the CSA store.

Application

The application of O. Reg. 490/09 varies for each of the designated substances.

While the application of the regulation is highly fact specific, examples are provided in this guide for illustrative purposes only.

The presence of a designated substance in the workplace alone does not necessarily mean that the regulation applies. For instance, with the exception of ethylene oxide, the likelihood of worker exposure to the designated substance must also exist.

For example, with respect to lead, a workplace such as a retail establishment where the sole presence of lead is in the form of lead bullets being sold in boxes, employers and workers would not be subject to the regulation for this substance as there is no likelihood of exposure. On the other hand, employers and workers at a workplace operating an indoor firing range using lead bullets as ammunition where a worker is likely to be exposed to dust containing lead that is produced when a bullet is fired would be subject to the regulation.

Workplace parties should refer to the application provisions of the regulation to see the various circumstances in which it may apply.  (Note: Refer to Chapter 2.6 of this guide for specific routes of exposures for designated substances).

Employers subject to the regulation must also consider their duty to third party workers set out at section 15 of the regulation.

Construction projects and other exceptions

A notable exception to the application of the regulation is related to construction projects. The regulation does not apply, at a project, to an employer who engages in construction (section 14), although please see the note below in Chapter 2.5 that describes how an employer to whom the regulation applies has certain obligations to third party workers which may, depending on the circumstances, extend to workers engaged in construction. Except for circumstances where O. Reg. 278/05 applies to asbestos, exposures to the designated substances on construction projects are addressed under regulation 833. Where there are asbestos exposures in or on a construction project, O. Reg. 278/05 applies to every owner (excluding owners of certain private residences), constructor, employer and worker engaged in or on the project.

There are other important exceptions to the application of the regulation. These are summarized below at a high level.  However, the “application” sections (sections 3-14) of the regulation should be carefully reviewed to determine if the regulation applies to your workplace.

Summary chart of application – O. Reg. 490/09

Designated substanceWhere regulation appliesWhere regulation does not apply
All designated substancesMost workplacesAt a project to an employer who engages in construction. (s. 14)
To farming operations (O. Reg. 414/05, s. 4)
AcrylonitrileEvery employer and worker at a workplace where acrylonitrile is present, produced, processed, used, handled or stored; and
At which a worker is likely to be exposed to the designated substance. (s. s.3(1))		To an employer or the workers of an employer at a workplace where acrylonitrile is not produced, processed or used if a worker’s exposure results only from the presence, use, handling or storage of goods made in the last stage of a process using polymers made from acrylonitrile. (s.s.3(2)).
ArsenicEvery employer and worker at a workplace where arsenic is produced, processed, used, handled or stored or is a waste product or by-product of a process; and
At which a worker is likely to be exposed to the designated substance. (s.s.4(1))		To mining operations, including concentrating, milling, washing, crushing, grinding, sifting or conveying of a metallic or non-metallic mineral or mineral-bearing substance or rock, unless the operations are carried on in a plant where smelting, roasting or refining is carried on, or in or at a place contiguous to such a plant. (s.s.4(2)).
AsbestosEvery employer operating a mine or mining plant for the purpose of mining, crushing, grinding or sifting asbestos; and

Those workers of such employer who are likely to be exposed to the designated substance. (clause 5(1)(a))

Every employer processing, adapting or using asbestos in connection with manufacturing or assembling of goods or products; and
Those workers of such an employer who are likely to be exposed to the designated substance. (clause 5(1)(b))

Every employer engaged in activities set out in ss.5 (2) (repair, alteration or maintenance of machinery, equipment, aircraft, ships, locomotives, railway cars and vehicles; work on a building that is necessarily incidental to the repair, alteration or maintenance of machinery or equipment) and to those workers of such an employer who are engaged in those activities and are likely to be exposed to asbestos if, on or before December 16, 1985, the employer put into effect and maintained measures and procedures to control the exposure of workers to asbestos and incorporated those measures and procedures into a control program  that has been maintained in accordance with the regulations.

Note: Majority of employers engaged in activities set out in s.s.5 (2) are covered under O. Reg. 278/05.		Employers and workers engaged in activities set out in s.s.5 (2) that are not grandfathered under clause 5(1)(c).
O. Reg. 278/05 would apply to those employers and workers: see s. 2(3) of O. Reg. 278/05.
BenzeneEvery employer and worker at a workplace where a worker is likely to be exposed to benzene or a product containing benzene during its transportation or transfer, or during its manufacture, processing, use, handling or storage (s.s.6(1)).To pumping gas into the fuel tanks of motor vehicles, motorboats or other watercraft, or into a portable container at a service station or other premises (s.s.6(2)).
Coke oven emissionsEvery employer and worker who works at a metallurgical coke oven; and is likely to be exposed to the designated substance. (s.7)N/A
Ethylene oxideEvery employer and worker at a workplace where ethylene oxide is present (s.8).N/A
IsocyanatesEvery employer and worker at a workplace where isocyanates are produced, used, handled or stored; and
At which a worker is likely to be exposed to the designated substance. (s.9)		N/A
LeadEvery employer and worker at a workplace where lead is present, produced, processed, used, handled or stored; and
At which a worker is likely to be exposed to the designated substance. (s.10)		N/A
MercuryEvery employer and worker at a workplace where the mercury is present, produced, processed, used, handled or stored; and
At which a worker is likely to be exposed to the designated substance. (s.s.11(1))		To an employer who is engaged in the practice of dentistry or who has one or more workers who engage in that practice, and to a worker who works in such an employer’s office (s.s.11(2)).
SilicaEvery employer and worker at a workplace where silica is present, produced, processed, used, handled or stored; and
At which a worker is likely to be exposed to the designated substance. (s.12)		N/A
Vinyl chlorideEvery employer and worker at a workplace where vinyl chloride is present, produced, processed, used, handled or stored; and
At which a worker is likely to be exposed to the designated substance. (s.13)		N/A

Role of joint health and safety committees (JHSC)

Many of the requirements in the regulation must be implemented by the employer in consultation with the JHSC established under section 9 of the OHSA*.

The JHSC must be consulted and can make recommendations regarding the assessment the employer must carry out of the exposure or likelihood of exposure of a worker to a designated substance in the workplace** (subsection 19(3)) and the development of the control program (subsection 20(7)).

Every member of the committee must be given copies of both the assessment (subsection 19(4)) and the control program (subsection 20(8)).

The committee must be consulted with respect to industrial hygiene testing (clause 9(18)(f) and subsection 11(1) of OHSA) and provided with the results of air monitoring tests (section 25).

* All workplaces subject to the regulation (refer to Chapter 2.3 above) must have a JHSC (clause 9(2)(c) of OSHA).  A JHSC established under clause 9(2)(c) of OHSA is required as long as the regulation continues to apply to the workplace.

**The assessment for the purposes of subsection 19(3) differs from the preliminary assessment of the likelihood of exposure to determine whether the regulation applies.  For example, the assessment required under subsection 19 (3) is more detailed, must be conducted in consultation with the JHSC, includes a determination of whether or not the health of the worker could be affected by the exposure, and must be in writing.  Except for certain circumstances involving ethylene oxide, the results determine whether a control program is needed or not.

Employer duty to third party workers

Employers to whom the regulation applies have a general duty to take every precaution reasonable in the circumstances to ensure the protection of a worker who is not a worker of the employer, is working in the employer’s workplace, is exposed to the designated substance and whose health is likely to be affected by exposure to the designated substance (subsection 15(1)).

Workers are required to comply with the requirements set out by the employer for the protection of the worker (subsection 15(2)).

Note: While the regulation does not apply, at a project, to an employer who engages in construction, an employer’s duty in s. 15 may, depending on the circumstances, extend to workers who are engaged in construction.

Exposure to designated substances

“Exposure” is defined in O. Reg. 490/09 as meaning exposure by inhalation, ingestion, skin absorption or skin contact.

Inhalation is a major route of exposure for all designated substances.  Other routes of exposure may be more important for some substances than others. They are noted in the chart below and should be considered when assessing workplace exposures.

Summary chart of primary route(s) of exposure
SubstancePrimary r oute(s) of exposure
AcrylonitrileInhalation, ingestion, skin absorption, skin contact
ArsenicInhalation, ingestion, skin absorption, skin contact
AsbestosInhalation, ingestion
BenzeneInhalation, skin absorption, skin contact
Coke oven emissionsInhalation, skin absorption
Ethylene oxideInhalation, skin absorption
IsocyanatesInhalation, skin contact
LeadInhalation, ingestion, skin absorption (organic lead compounds)
MercuryInhalation, ingestion, skin absorption (organic mercury compounds)
SilicaInhalation
Vinyl chlorideInhalation, skin absorption

Employer duty to limit airborne exposure

Controlling exposure

Employers have a duty to take all necessary measures and procedures by means of engineering controls, work practices and hygiene facilities and practices to ensure that a worker’s airborne exposure to a designated substance  does not exceed the Occupational Exposure Limit (OEL) set out in O. Reg. 490/09 and, depending on the designated substance, is reduced to the lowest practical level (section 16).

Under certain conditions, the employer’s duty to limit airborne exposure to designated substances may include providing workers with respirators (section 18),

Details on these control measures and procedures must be included in the control program. More information on these controls is found in Chapter 4 of this guide.

When respirators can be used

Wearing respirators can be uncomfortable and their care and use must be closely monitored to ensure workers are properly protected. With some exceptions, respirators are normally considered to be the last line of defence or control against airborne hazards and there are restrictions on their use.

Section 18 of the regulation sets out the conditions when an employer must provide a respirator to reduce worker exposure if the employer cannot comply with the strict duties imposed in section 16 for one of the following reasons:

  • an emergency exists (for example, where workers are exposed to immediate danger, such as process upset, a spill or equipment breakdown)
  • control measures/procedures do not exist or are unavailable
  • control measures/procedures are not reasonable or practical for the length of time or frequency of exposure or the nature of the process, operation or work
  • control measures/procedures are not effective because of a temporary breakdown of equipment

Regardless of the airborne levels of a designated substance, the regulation also provides that a worker who is exposed may at any time request a respirator and the employer must provide it (subsection 18(2)).

Where respirators are provided, the respiratory protection program provisions of the regulation must be complied with (subsection 18(3)). More information on the respiratory protection program can be found in Chapter 6 of this guide.

Occupational exposure limits (OELs)

OELs restrict the amount and length of time a worker can be exposed to hazardous biological or chemical agents, including designated substances.

There are three different OELs specified in the regulation:

  • The time-weighted average limit or TWA is the time-weighted average airborne concentration of the substance that a worker may be exposed to over the course of a workday or work week. It is based on an 8-hour workday or 40-hour work week.
  • The ceiling limit or C is the maximum airborne concentration of the substance agent to which a worker may be exposed at any time.
  • The short-term exposure limit or STEL is the maximum airborne concentration of substance to which a worker may be exposed in any 15-minute period, no more than four times during an eight-hour work shift and with at least one hour between exposures.

The OELs for the designated substances are set out in Table 1 “Exposure Limits” of O. Reg. 490/09. They are also found in Table 1 “Ontario Table of Occupational Exposure Limits” in regulation 833, which applies to workplaces that do not fall under O. Reg. 490/09 or, in the case of asbestos, a workplace that is subject to O. Reg. 278/05.

See a complete list of all OELs applicable to Ontario workplaces.

For some designated substances, employers are required to reduce airborne exposure to the “lowest practical level” (subsection 16(2)). The lowest practical level depends on the individual characteristics of the workplace. The employer should take into consideration what can realistically and reasonably be done to the workplace, equipment, processes and exposure control methods by way of improvement, modification and replacement to reduce exposures below the TWA.

Other isocyanates

For isocyanates other than those listed in Table 1 of the regulation, an employer must:

  • adopt and implement all such engineering controls, work practices and hygiene practices that are reasonable and practical
  • provide workers who handle, dispense, mix, apply, use, transfer, dispose of or deal with isocyanates and are likely to inhale or come into contact with isocyanates, with appropriate personal protective equipment (section 17)

Workers are required to wear and use the personal protective equipment provided by their employer when working with the above isocyanates (subsection 17(2)).

Measuring airborne exposures

Air monitoring refers to a procedure for determining the concentration of a contaminant in workplace air. The results are used in the assessment of worker exposures by inhalation.

Section 24 of the regulation sets out requirements for air monitoring and sampling to ensure that employers do so properly and that the results accurately reflect workplace conditions and worker exposures to airborne concentrations of the designated substance.

A key requirement of section 24 is that air monitoring be performed by or under the direction of a person who is qualified, because of knowledge, training and experience, in industrial hygiene practice. The procedures for monitoring, sampling and determining airborne concentrations and worker exposure to airborne concentrations of a designated substance must comply with:

  • a standard method for workplace air sampling and analysis, as defined in the regulation, or another method recognized in industrial hygiene practice
  • the rules set out in Part I of Schedule 1 of the regulation, “Airborne Measurement and Calculation of Exposure”

Employers must consult and provide information to the JHSC about proposed testing strategies and allow a worker JHSC member to be present at the beginning of the testing in certain circumstances (section 11 of OHSA).

The employer must do the following with the air monitoring results under a control program:

  • promptly post them in a conspicuous place(s) where they are most likely to come to the attention of workers who would be affected by them
  • leave them posted for at least 14 days
  • provide them to the JHSC
  • keep them for at least five years (section 25)

Further information on air monitoring and section 24 of the regulation is found in Chapter 7 of this guide.

Workplace assessments

Details on conducting an assessment are discussed in Chapter 3 of this guide.

When an assessment is required

An assessment is required at every workplace to which the regulation applies (section 19). It is a detailed examination of the workplace and workplace practices to determine:

  • whether workers are exposed to the designated substance at present or whether   they are likely to be exposed in the future
  • whether or not the health of a worker may be affected by exposure to the substance

The employer must carry out the assessment in consultation with the JHSC. The JHSC may make recommendations respecting the assessment. Workplace personnel familiar with work processes, and if necessary, specialists in occupational health and industrial hygiene should be engaged.

If an employer chooses to engage an outside party to perform the assessment, the employer remains responsible for ensuring that the assessment is conducted in accordance with the regulation.

The completed assessment must be in the form of a written report and the employer must give a copy of the report to each JHSC member.

Conclusions reached in the assessment will assist the employer and the JHSC in deciding whether a control program is required.

Further assessments are needed whenever there is a change* in a workplace that could result in a significant difference in the exposure of a worker to a designated substance (section 22).

* For the purposes of section 22, “change” means, (a) a change in a process involving a designated substance or in the methods and procedures in which the substance is produced, mined, processed, used, handled or stored, as the case may be; and (b) in the case of coke oven emissions, a change in metallurgical coking operations (subsection 22(1)).

What to consider when conducting an assessment

In performing the assessment, the employer must consider and take into account different factors depending on the designated substance, including:

  • the methods and procedures used or to be used in the operation involving the designated substance
  • the actual and potential extent of a worker’s exposure to the designated substance
  • the measures and procedures necessary to control exposure by means of engineering controls, work practices and hygiene facilities and practices

Control programs

More information on control programs can be found in Chapter 4 of this guide.

When a control program is required

A control program sets out the measures and procedures to protect workers from exposure to the designated substance, monitor the exposures and monitor worker health. It must be developed when the assessment reveals or would reveal that a worker is likely to be exposed to the designated substance and that the health of the worker may be affected by such exposure (subsection 20(1)).

The employer is responsible for developing, establishing, putting into effect and maintaining measures and procedures that are incorporated in the control program and must do so in consultation with the JHSC. Control programs must provide for the basic requirements set out in section 20 of the regulation.

Note: Special exceptions to the requirements for control programs apply to ethylene oxide in certain circumstances. Refer to section 21 of the regulation for details on the emergency program respecting ethylene oxide.

What must be included in a control program

Every control program must provide for the following:

  • Engineering controls, work practices and hygiene facilities and practices to control worker exposure to the designated substance (subsection 20(2), para. 1). See Chapters 5 and 6 of this guide for more information.
  • Methods and procedures to monitor both the airborne concentrations of the designated substance in the workplace and worker exposure to the substance (subsection 20(2), para. 2). See Chapter 7 of this guide for more information.
  • Workers’ personal records of exposure to the designated substance at the workplace maintained by the employer (subsection 20(2), para. 3 and subsection 20(6), paras. 1 and 2).
  • Note: A copy of these records must be given by the employer to the physician who examines the worker or supervises clinical tests on a worker (section 27).
  • Workers’ personal records of medical examinations and clinical tests maintained by physicians who have examined a worker under the control program or who performed or supervised clinical tests on a worker (subsection 20(2), para. 3 and subsection 20(6), para. 3).
  • A training program for supervisors and workers on the health effects of the designated substance and the measures and procedures to control worker exposures (subsection 20(2), para. 4).
  • In the case of a control program respecting coke oven emissions, the specific requirements set out in Part II of Schedule 1 to the regulation (subsection 20(3)).
  • In the case of a control program respecting asbestos, benzene, coke oven emissions, isocyanates, lead, mercury or silica, medical examinations and clinical tests in accordance with the Code for Medical Surveillance for Designated Substances (subsection 20(4)). Refer to Chapter 8 of this guide for more information.

The completed control program must be in the form of a written document. The employer must give a copy of the control program to each JHSC member and must make it available to workers in English and in the majority language of the workplace. The employer must also acquaint every worker affected by the program with its provisions (subsection 20(8)).

Handling disputes

In the event of a dispute between the employer and the JHSC over an assessment, measures and procedures, a control program or, in the case of ethylene oxide, an emergency program, either the employer, the JHSC or a JHSC member may notify a ministry inspector* of the dispute and the inspector must investigate and give a decision in writing to the employer and joint health and safety committee (section 23).

* Notification to the Ministry’s Health and Safety Contact Centre at 1-877-202-0008 fulfills this requirement.