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Appendix 1 - Medical surveillance of silica-exposed workers
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.
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.
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.
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).
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.
Respirator Requirements & Other Measures and Procedures for Type 1, 2, and 3 Silica-Containing Operations
|Type||Operations||Required Respirator||Other Measures & Procedures|
|Type 1||Half-mask particulate respirator with N-, R-, or P-series filter and 95, 99 or 100% efficiency.|
Full-facepiece air-purifying respirator with N-, R-, or P-series filter and 100% efficiency.
Tight-fitting powered air-purifying respirator with a high-efficiency filter.
Full-facepiece supplied-air respirator operated in demand mode.
Half-mask or full-facepiece supplied air respirator operated in continuous-flow mode.
(In addition to Type 1 measures and procedures.)
|Type 3||Type CE abrasive-blast supplied air respirator operated in a positive-pressure mode with a tight-fitting half-mask facepiece.|
Type CE abrasive-blast supplied air respirator operated in a pressure-demand or positive pressure mode with a tight-fitting full-facepiece.
(In addition to Type 1 and Type 2 measures and procedures.)