Disclaimer: This web 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.
The Regulation for Health Care and Residential Facilities (O. Reg. 67/93, s. 19) made under the Occupational Health and Safety Act (OHSA) requires that mechanical ventilation systems in the workplaces to which the regulation applies be inspected by a qualified person at least every six months. It also requires that a report on each inspection be filed with the employer and with the Joint Health and Safety Committee or the Health and Safety Representative, if any.
This guide identifies issues related to the inspection, service, and maintenance of ventilation systems to help employers and persons carrying out these tasks to determine how to comply with the requirements of the regulation and achieve a healthier workplace.
The two major types of mechanical ventilation systems, namely general ventilation (heating, ventilating and air-conditioning – HVAC) and local exhaust ventilation are discussed in this document.
The inspection must be carried out by a person who is qualified by training and experience to do so. He or she may be a worker in maintenance or some other area of the facility who has detailed knowledge of the system, and its operation and maintenance requirements. A qualified contractor with expertise in ventilation systems who is familiar with the system may also be qualified to conduct the inspection.
It is recommended that information about each ventilation system be recorded and be kept readily available at the workplace. The record should include:
For an air supply or re-circulating HVAC system, the records should include descriptions of:
Employers often find it helpful to keep a log or record of indoor air quality complaints and associated conditions.
Local exhaust ventilation systems, generally have four basic components: hood(s), duct network (including the exhaust duct, discharge stack and/or recirculation duct), air cleaning device and fan. The records for these systems should include descriptions of:
A good way to help ensure that a ventilation system is operating properly is by regularly checking the direct measurement of air flow rates/velocities at appropriate points.
For laboratory ventilation (e.g., general use laboratory hoods), flow rate or face velocity measurements are good indicators of system performance. For a local exhaust ventilation system, hood static pressure measurements can also serve well. Details of how and where to measure air flow may be obtained from ventilation references, such as Industrial Ventilation: A Manual of Recommended Practice for Design, 27th ed., 2010, published by the American Conference of Governmental Industrial Hygienists (ACGIH).
Indirect methods of assessing outdoor air supply of a mechanical ventilation system can be used with assumptions and limitations. For example, carbon dioxide (CO2) measurements may be used to assess the adequacy of general mechanical ventilation in general occupancy areas where human respiration is the main source of CO2. However, this method is not appropriate for assessing ventilation adequacy in areas where hazardous airborne contaminants are being, or may be, released (e.g., sterilizer rooms, surgery and recovery rooms, incinerator rooms).
Where CO2 measurements are appropriate, they should be taken at a time of relatively high occupancy and under both summer and winter conditions. The American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) standard 62.1- 2010 Ventilation for Acceptable Indoor Air Quality recommends an outdoor air ventilation rate of 17 cfm (cubic feet per minute) per person/8.5 litres per second per person for a typical office space, based on an estimated maximum occupancy of five (5) people per 1,000 ft2 (100 m2). At this ventilation rate, a steady-state CO2 concentration of greater than about 600 ppm above outdoor levels in a typical office space (assuming that make-up air is of satisfactory quality and outside CO2 concentrations are in the 300 to 500 ppm range) may indicate an insufficient supply of fresh outside air. This should trigger a visual inspection of the relevant ventilation system(s).
However, whether or not testing is done, for ongoing ventilation system effectiveness, regular visual inspections under a preventive maintenance program are necessary. Visual inspection is needed to ensure the integrity, cleanliness and proper operation of the system. A list of some recommended items/ventilation system components to be checked during a semi-annual inspection is provided in Section 5.
Check each of the following items, as applicable:
The person conducting the semi-annual inspection is required to file a report with the employer and with the Joint Health and Safety Committee or the Health and Safety Representative, if any. It is recommended that the report states what was inspected, when and by whom. It should describe any deficiencies observed during the inspection. If deficiencies are found, action should be taken to correct them. Deficiencies and the corrective action(s) should be documented in the system records.
O. Reg. 67/93, s. 19 (5) requires mechanical ventilation system:
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