Ventilation Effectiveness in Reducing Aerosol Particle Concentrations in Classrooms and Graduate Student Offices Pertaining to the COVID-19 Pandemic

The SARS-CoV-2 virus can be spread by inhalation of infected saliva aerosol particles produced when coughing, sneezing, laughing, singing, talking, or breathing. Indoors, these fine particles will continue to spread through the air in the room and a person can be exposed by a nearby infected person speaking or coughing. In this research, our motivation is to investigate the spread of airborne saliva aerosol particles in classrooms and graduate student offices. Graduate student offices can also also be considered as a good representative of any closed office space. The testbed will be classrooms and offices at the Faculty of Science at McGill University. While the amount of endogenous saliva aerosols is small compared to the overall values of particle concentrations in the air, it is these human-produced saliva particles that are of concern for airborne transmission of COVID-19. Therefore, we propose measurements that will estimate the amount of endogenously versus exogenously generated aerosol particles in occupied classrooms and offices. The classroom measurements will consider the following six occupancy scenarios: (1) 20 males and ventilation system on; (2) 20 females and ventilation system on, (3) 10 males and 10 females and ventilation system on; and (4-6) same as (1-3) but ventilation system off. In all cases, a lecturer will be an additional person in the classroom giving a 30 min talk. The measurements will be initiated 15 min before people enter the classroom to estimate the ambient (i.e., exogenous) concentration values of aerosols. Moreover, the measurements will be performed at different heights and locations in the investigated rooms to estimate how the concentrations vary spatially. In addition, we shall measure air temperature, relative humidity, and CO2 concentrations to support the interpretation of aerosol concentration data. The office measurements will be performed with 4 graduate students in an office with and without a ventilation system.