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Appendix 1 - Medical Surveillance of Silica-Exposed Workers: Silica On Construction Projects

  • Issued: September 2004
  • Updated: April 2011
  • Content last reviewed: April 2011

Disclaimer: This resource has been prepared to help the workplace parties understand some of their obligations under the Occupational Health and Safety Act (OHSA) and regulations. It is not legal advice. It is not intended to replace the OHSA or the regulations. For further information please see full disclaimer.

Where construction workers are exposed to airborne silica, measures and procedures to control their exposure should be implemented. This Guideline has outlined (in Section 4) the types of controls that should be in place for various work activities. However, even with the appropriate measures to control the silica hazard, some workers may be affected. Workers should therefore be periodically examined to determine if they are experiencing any adverse effects.

The essential features of a silica medical surveillance program are presented below.

Medical Surveillance Program


The objective of a medical surveillance program is to protect the health of workers by:

  • ensuring their fitness for exposure to silica
  • evaluating their absorption of silica
  • enabling remedial action to be taken when necessary
  • providing health education.


The medical surveillance program should include the following:

  • pre-employment and pre-placement medical examinations
  • periodic medical examinations
  • clinical tests
  • health education
  • record keeping.

Medical Examinations

The medical examination should include the following:


The initial medical and occupational history should include enquiries about the worker's previous exposure to silica, personal habits (smoking) and history of present or past respiratory disorders (particularly tuberculosis). At the periodic examination, the history shall be updated to include:

  • information on the frequency and duration of exposure to silica since the previous examination; and
  • the occurrence of signs and symptoms of respiratory disease, e.g., dyspnea, cough, sputum, haemoptysis, wheezing and chest pain.

Physical Examination

Medical surveillance should include a general physical examination, with attention particularly directed to the respiratory system. The frequency of periodic examinations will depend on the intensity and length of exposure to silica and should be decided by the examining physician. It need not be the same for all workers but should not be less than once every two years.

Clinical Tests

X-rays and pulmonary function tests should be taken to assess a worker's fitness for continued exposure to silica. Refer to the Code for Medical Surveillance of Silica Exposed Workers in O. Reg. 490/09 for specific requirements.

To avoid unnecessary x-rays at a pre-placement medical examination, the examining physician should, where practicable, obtain the medical status from another facility if the worker has been previously examined in the past year. Radiographs should be closely examined for early signs of silicosis or other chest disease.

When exposure is discontinued, the frequency of X-rays and the period of surveillance will depend on the intensity and duration of exposure and the findings in previous X-rays. The examining physician shall determine the duration and frequency of follow-up

Pulmonary Function Tests

Pulmonary function tests should be taken in conjunction with the chest X-rays. Calibration of the instruments should meet current standards. Tests should include FEV1, FVC, FEV1/FVC per cent and a mid-flow rate such as FEF 25-75 per cent. All relevant data should be corrected to body temperature and pressure (BTPS).

Action Levels

An assessment of a worker's fitness for work should be based on both the clinical examination and clinical test results. For this reason, no specific action levels are stated for the latter. If silicosis is confirmed, the physician should then determine whether the worker is fit, fit with limitations or unfit for further exposure. A worker should not be removed from silica exposure before consultation with the Workplace Safety Insurance Board (WSIB). To qualify for compensation or rehabilitation further assessment by the WSIB will be necessary.

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Disclaimer: This web resource has been prepared to assist the workplace parties in understanding some of their obligations under the Occupational Health and Safety Act (OHSA) and the regulations. It is not intended to replace the OHSA or the regulations and reference should always be made to the official version of the legislation.

It is the responsibility of the workplace parties to ensure compliance with the legislation. This web resource does not constitute legal advice. If you require assistance with respect to the interpretation of the legislation and its potential application in specific circumstances, please contact your legal counsel.

While this web resource will also be available to Ministry of Labour inspectors, they will apply and enforce the OHSA and its regulations based on the facts as they may find them in the workplace. This web resource does not affect their enforcement discretion in any way.