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

Purpose

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.

Program

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:

History

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.

Respirator Requirements & Other Measures and Procedures for Type 1, 2, and 3 Silica-Containing Operations

TypeOperationsRequired RespiratorOther Measures & Procedures
Type 1
  • The drilling of holes in concrete or rock that is not part of a tunnelling operation or road construction.
  • Milling of asphalt from concrete highway pavement.
  • Charging mixers and hoppers with silica sand (sand consisting of at least 95 per cent silica) or silica flour (finely ground sand consisting of at least 95 per cent silica).
  • Any other operation at a project that requires the handling of silica-containing material in a way that may result in a worker being exposed to airborne silica.
  • Entry into a dry mortar removal or abrasive blasting area while airborne dust is visible for less than 15 minutes for inspection and/or sampling.
  • Working within 25 metres of an area where compressed air is being used to remove silica-containing dust outdoors.
Half-mask particulate respirator with N-, R-, or P-series filter and 95, 99 or 100% efficiency.
  • Clean-up after each operation should be done to prevent dust containing silica from spreading
  • Compressed air or dry sweeping should be avoided when cleaning a work area
  • Compressed air should not be used for removing dust from clothing
  • Workers exposed to silica should be provided with or have access to washing facilities equipped with clean water, soap, and individual towels
  • Silica dust on personal protective clothing and equipment should be removed by damp wiping or HEPA vacuuming
  • Contaminated personal protective clothing and equipment should be handled with care to prevent disturbing the silica dust and the generation of airborne silica dust
  • Washing facilities and laundering procedures must be suitable for handling silica contaminated laundry
  • Warning signs should be posted in sufficient numbers to warn of the silica hazard. There should be a sign, at least, at each entrance to the work area. The signs should display the following information in large, clearly visible letters:
    • There is a silica dust hazard.
    • Access to the work area is restricted to authorized persons.
    • Respirators must be worn in the work area.
Type 2
  • Removal of silica containing refractory materials with a jackhammer.
  • The drilling of holes in concrete or rock that is part of a tunnelling operation or road construction.
  • The use of a power tool to cut, grind, or polish concrete, masonry, terrazzo or refractory materials.
  • The use of a power tool to remove silica-containing materials.
  • The use of a power tool indoors to chip or break and remove concrete, masonry, stone, terrazzo or refractory materials.
  • Tunnelling (operation of the tunnel boring machine, tunnel drilling, tunnel mesh installation).
  • Tuckpointing and surface grinding.
  • Dry mortar removal with an electric or pneumatic cutting device.
  • Dry method dust clean-up from abrasive blasting operations.
  • The use of compressed air outdoors for removing silica dust.
  • Entry into area where abrasive blasting is being carried out for more than 15 minutes.

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.)

  • Other workers entering a work area where Type 2 operations are being performed should remain at least 10 metres away. Ropes or barriers should be set up to prevent unauthorized personnel from entering the work area. If this is not possible and there are workers within the 10-metre limit, the Type 2 operation should be enclosed to prevent the escape of airborne silica-containing dust ( partial or full enclosures).
Type 3
  • Abrasive blasting with an abrasive that contains ≥1 per cent silica
  • Abrasive blasting of a material that contains ≥ 1 per cent silica
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.)

  • While abrasive blasting is in progress or the airborne dust from abrasive blasting is visible,
    • any worker entering the work area where abrasive blasting is being carried out for less than 15 minutes for inspection and/or sampling purposes should wear a half-mask particulate respirator with N-, R-, or P-series filter and 95, 99 or 100% efficiency.
    • any worker entering a work area where abrasive blasting is being carried out for more than 15 minutes should wear a respirator with a NIOSH APF of 50
    • workers engaged in cleaning dust from abrasive blasting operations, should wear a respirator with a NIOSH APF of 50
  • Where abrasive blasting is conducted, barriers, partial enclosures and full enclosures should be in place to prevent other workers from being exposed to silica-containing dust and to prevent the spread of dust to other work areas.