The assessment

The regulation requires an assessment to determine the extent to which workers are exposed to a designated substance. Assessments must comply with the requirements in section 19 and, if a further assessment is required due to a change in the workplace, the requirements in section 22. Assessments should be undertaken in a step-by-step manner and tailored to the specific workplace. The following information in this chapter outlines key steps that may help guide you in conducting an assessment.

Step 1: information collection

In your workplace, identify materials that contain the designated substance, determine how the substance is used in the workplace and the quantities of the substance used. To assist, review safety data sheets and packaging information on products.

Obtain a copy of the workplace layout and process flow diagrams and develop a process flow sheet for each process that shows what happens to the designated substance from the time it enters the workplace until it leaves or until there is no longer a risk of exposure.

Obtain existing data on processes and current control measures and procedures in place and record the following information, if available:

• engineering controls:
  • location and types of ventilation systems used
  • measures taken to isolate or physically enclose the equipment or process
• work practices, including administrative controls, to reduce the duration of worker exposure
• hygiene facilities and practices to prevent contamination of skin and clothing
• use of personal protective equipment and clothing
• air monitoring and results
• contingency plans for spills or equipment breakdowns
• medical surveillance programs, if in existence
• training programs on health effects of the designated substance and control measures

Step 2: workplace site inspection

Using the workplace layout and process flow sheets as a guide, carry out a workplace inspection, observing each process to determine the potential for exposure of workers to the substance. All information collected during the inspection should be recorded.

One method of recording information is to develop a chart based on the workplace layout, survey the locations/processes where the designated substance is present , produced , processed , used , handled and/or stored and then record findings.

The inspection should be carried out at a time that is most representative of the work conditions. Change in exposures as a result of intermittent or infrequent operations, differences in night versus day operations and seasonal differences in workplace conditions (for example, windows open or closed) should be noted and taken into consideration.

The employer is required to carry out the assessment in consultation with the JHSC, which may make recommendations. Both worker and management members of the JHSC should participate in the inspection. As the inspection proceeds, the following items should be noted:

• Where and how is the substance used?
• Is there a possibility of the substance being released into the air and in what form?
• How many workers are in each area/performing each job? How long?
• Do workers encounter the substance? If yes, what is the risk of exposure (such as, inhalation, ingestion, skin contact or absorption)?
• Is there evidence of contamination and poor housekeeping practices? (for example, dust on workers or equipment, strong smell)
• Location and type of engineering controls.
• Hygiene facilities and practices.
• Do workers use respirators and other personal protective equipment? If yes, what type and how often?
• Have workers complained of any acute or chronic health effects (for example, headaches, shortness of breath, coughs) that may be related to exposure to the designated substance in the workplace?  
• Are workers aware of safety precautions and procedures when working with the designated substance?  

Step 3: air sampling

Following the inspection, arrangements for air sampling should be made if either:

• t here is reason to believe that the health of workers may be affected by exposure to a designated substance
• t he airborne concentration of a designated substance may be near or greater than the OELs

See chapter on air monitoring and exposure records, for details.

Step 4: data analysis

All information gathered from the review of existing data, workplace inspection and, if carried out, air sampling, should be analysed to determine:

• the actual and potential exposure of workers to the designated substance
• the adequacy of existing control measures
• any further measures necessary to control exposures

Step 5: assessment findings and report

The assessment report should include a summary of the information gathered and analysis of any data, including sampling data. Prior to finalization, the assessment should be reviewed with the JHSC.

The report must state whether there is a likelihood of worker exposure to the designated substance and whether the health of a worker may be affected by the exposure, which informs whether a control program is necessary under s. 20. The conclusion of the assessment will determine whether or not a control program is necessary.  

The following provides examples of scenarios and conclusions as to whether a control program is required depending on the results of the employer’s assessment per s. 19. As with all examples provided in this guide, they are provided for illustrative purposes only and are not determinative.

Note: The workbook for designated substances assessments prepared by Workplace Safety & Prevention Services may be a useful resource and is available for free.