The ways of managing an HVAC system to reduce the risk as much as possible at the same time to reduce the airborne levels of COVID-19 as low as reasonably achievable can be quite different depending on the system’s file user and the typology of the duct layout. Thus, you have to refer to the specific system applications and typology. What is common to reduce the risk is the goal: to provide as much as possible outdoor air to dilute and remove through the exhaust air vents any possible SARS-CoV2-19 virus exhaled by an asymptomatic person present in the space or room serviced by the HVAC system. . This including sufficient and effective ventilation, possibly enhanced by particle filtration and air disinfection, and avoidance of air recirculation and avoiding overcrowding.