Published July 8, 2021
Lab Department of Mechanical and Aerospace Engineering
University at Buffalo
Air is the primary carrier of pathogens that can be transmitted through respiratory actions such as breathing, talking, sneezing, and coughing. These pathogens are released as droplets at varying velocities and diameters. Small droplets linger in the air for a prolonged period, increasing the risk of infecting to other individuals present in the same room. Larger droplets fall to surfaces within a few seconds, increasing the risk of infection through direct contact. Therefore, the flow dynamics of air plays an important role in determining the movement and concentration of pathogens. The air sterilization technology SteriSpaceTM, developed by a local company You First Services, destroys airborne biological pathogens and can be a stand-alone unit for a room or integrated into a building air handling system and can be customized for different configurations. Computational fluid dynamics (CFD) can be used to predict the air flow patterns in an indoor space to optimally determine the location of the return ducts such that most of the pathogens exit the room.
A clinical setting is modeled where a patient might visit a doctor or dentist. The patient is seated and two people are present wearing face masks. If the patient is contagious and sneezes, it is possible to visualize where the air and virus travel. The ventilation uses a single exhaust (return) vent above the patient and a single diffuser (supply) vent. The first case (movie 1) demonstrates how the sneeze transports within a room using a conventional ventilation system that operates with 3 air changes per hour. The second case (movie 2) demonstrates how the SteriSpace Air Sterilization unit improves the removal of pathogens and sterilizes them. The SteriSpace unit increases air flow providing 6 air changes per hour. It can be seen that there are more sneeze particles in the air above the patient for the conventional system scenario than a room utilizing a SteriSpace system. The air and respiratory particles are recirculated through the conventional system, and what enters the supply vent are still virus-containing, whereas the particles using the SteriSpace system are sterilized (thus no pathogens are visible). As time continues to elapse, there are more particles diffused through the room with the conventional ventilation system and far less contagious particles in a room that uses SteriSpace.