COVID-19 frequently asked questions: General ventilation and air circulation
During the course of the current pandemic, public health experts advise that activities should be moved outdoors wherever possible. For activities that take place indoors, basic principles of good indoor air quality include supplying outdoor air to replenish indoor air by removing and diluting contaminants that naturally accumulate in indoor settings, especially in well-sealed buildings.
Can the virus that causes COVID-19 spread through a ventilation system?
At this time, there is no evidence that a building’s ventilation system, in good operating condition, is contributing to the spread of the virus.
What can I do to make sure my ventilation system is operating properly?
- It is a requirement for employers to ensure that heating, ventilation and air conditioning (HVAC) systems are designed, operated, and maintained as per standards and specifications for ongoing comfort for workers (Part 4 of the OHS Regulation).
- Ensure preventative maintenance is conducted (for example, regular filter changes and inspection of critical components).
- Make sure the system is properly balanced, which means verifying that the system meets its design conditions for air flow, temperature, pressure drop noise and vibration.
How can I ensure the healthiest indoor air quality in my workplace during the COVID-19 pandemic?
- Reduce air recirculation and increase the outdoor air intake as much as possible while maintaining comfortable indoor temperature and humidity. Check to ensure that 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, if you wish to save power.
What can I do to improve the ventilation if I don’t have a HVAC system for my workplace?
- If feasible, open windows and doors to promote air circulation.
- Post occupancy limits to allow for adequate physical distancing in every room, and do not allow overcrowding.
- Air cleaning devices that have a HEPA filter will reduce particles in the air and can be used in rooms with poor air circulation.
- If portable fans or air conditioning units are used, they should be set up to avoid blowing air directly from one person’s breathing zone to other occupants of a room. Horizontal cross breezes should be avoided. Rather, set up devices so that air flow moves downward from the ceiling.
What about ventilation in vehicles?
- Workers using company vehicles should turn the vents or air conditioning controls to allow outdoor air to flow in. Do not set the vents to recirculate.
- Windows should be left partially open to allow as much outdoor air as possible into the vehicle.
Is there anything special I have to do to my ventilation system before my employees return to work?
- If the building was unoccupied for a period of time, ensure your system is put back into operation after a thorough inspection. If your building system includes a cooling tower you must assess the risk of Legionella contamination and disinfect your system as required.
- Maintenance workers of HVAC systems are required to 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 for the virus is necessary when usual safe work procedures are followed.