Knowledge Base

We have an ISO level 8 facility air exchange in certain rooms of once an hour. Does high-volume air exchange affect some of the precautions as far as distancing and additional PPE? Are there some specifications on air exchange?


In general, while there is plausibility of COVID-19 transmission by inhaled virus in air particularly in crowded, poorly ventilated settings, there is limited epidemiological evidence that this occurs. Specifically, the overall scientific evidence does not indicate that transmission of COVID-19 occurs via HVAC systems at this time. Although viral RNA has been detected in air and HVAC systems, the viability of virus in or infection from air circulated through HVAC systems has not been demonstrated. 

Enhancing outdoor air ventilation and good maintenance of HVAC systems will complement other public health measures to reduce COVID-19 transmission, e.g., screening, self-isolation when sick, physical distancing, hand hygiene, respiratory source control, environmental cleaning and disinfection 

Good ventilation is important in indoor environments for the general health and comfort of occupants. Optimization of HVAC systems can be done on the basis of best practices for ventilation, as COVID-19 transmission from HVAC systems has not been observed. In general, avoiding stagnant air conditions and ventilating indoor environments with fresh outdoor air, whether by increasing the outdoor air ratio of the HVAC system or by opening windows, will dilute exhaled air from the occupants including any infectious particles. Thus, most guidance encourage ventilation with outdoor air, avoiding recirculation as far as practically possible and ensuring clean filters  


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).