Ventilation and air circulation

Prevent the spread of communicable disease

Public health experts advise that moving activities outdoors whenever possible can minimize the spread of communicable disease. For indoor activities, you can improve indoor air quality by supplying outdoor air, which will help remove and dilute contaminants that naturally accumulate in indoor settings, especially in well-sealed buildings.

Frequently asked questions

At this time, there is no evidence that a building’s ventilation system, in good operating condition, contributes to the spread of communicable disease.

Employers must ensure that a place of employment is adequately ventilated by mechanical ventilation that conforms to ASHRAE standard 62-1989, “Ventilation for Acceptable Indoor Air Quality." See section 20(1)(b) of Regulation 91-191.

Make sure preventative maintenance is conducted according to the manufacturer’s requirements (for example, regular filter changes and inspection of critical components).

Make sure the system is properly balanced. Verify that the system meets its design conditions for air flow, temperature, pressure drop, noise and vibration.

If you’re using portable fans or air conditioning units, make sure they’re set up to avoid blowing air directly from one person’s breathing zone to other occupants of a room. Avoid horizontal cross breezes. Instead, set up the devices so air flow moves downward from the ceiling.

Reduce air recirculation and increase the outdoor air intake as much as possible while maintaining a comfortable indoor temperature and humidity. Make sure outdoor air dampers are operating properly.

Do not turn off the ventilation system while the building is occupied. After working hours or on weekends, consider turning the system down, rather than turning it off.

Workers using company vehicles should adjust the vents or air conditioning controls to allow outdoor air to flow in. Do not set the vents to recirculate.

Leave windows partially open to allow as much outdoor air as possible into the vehicle.

If the building has been unoccupied for an extended period of time, make sure your system has a thorough inspection before it’s put back into operation. Refer to the manufacturer specifications for details on inspection requirements. If your building system includes a cooling tower, you must assess the risk of Legionnaire’s Disease contamination and disinfect your system as required by the manufacturer.

HVAC maintenance workers must follow their usual safe work procedures, including the use of personal protective equipment normally worn to conduct maintenance. No special cleaning or disinfecting of the system is necessary when usual safe work procedures are followed.

Employers must ensure that a place of employment is adequately ventilated by natural ventilation, which introduces outside air provided by openings having a combined area equal to at least five per cent of the floor area. See section 20(1)(a) of Regulation 91-191.

When advised by Public Health, post occupancy limits to allow for adequate physical distancing in every room. Don’t allow overcrowding.

Air cleaning devices that have a High Efficiency Particulate Air (HEPA) filter will reduce particles in the air. You can use them in a room with poor circulation.

E-News Sign-up