Office Ventilation Increases COVID-19 Risk: Cambridge Study

The University of Cambridge announced on Wednesday, 30 September, that a research team, including Indian-origin expert Rajesh Bhagat, found that ventilation systems used in modern office buildings may increase the risk of exposure to the novel coronavirus.

According to a Hindustan Times report, the study found that the widely used ‘mixing ventilation’ systems, which are designed to keep conditions uniform in all parts of the room, disperse airborne contaminants evenly throughout the space. These contaminants may include droplets and aerosols, potentially containing viruses.

The novel coronavirus is transmitted primarily through smaller aerosols and larger droplets, which are emanated when people cough, talk, sneeze or breathe.

The data available on viral spread so far indicates that indoor transmission is far more likely than outdoor transmission. This is possibly due to increased exposure times and decreased dispersion rates for droplets and aerosols, the study led by Paul Linden of the Department of Applied Mathematics and Theoretical Physics (DAMTP) says.

The study, published in the Journal of Fluid Mechanics, examined various modes of viral expulsion, including speaking, breathing, laughing - both with and without face masks. The researchers imaged the heat associated with breath for each instance, to observe its movement through space.

“You can see the change in temperature and density when someone breathes out warm air – it refracts the light and you can measure it. When sitting still, humans give off heat, and since hot air rises, when you exhale, the breath rises and accumulates near the ceiling.”

Dr Rajesh Bhagat

The results of the experiment indicated that air circulation in closed rooms is turbulent and can change dramatically depending on the type of ventilation, movement of the occupants, the opening and closing of doors and, and for naturally ventilated spaces - changes in outdoor conditions. They also noted that masks are effective in limiting the transmission of exhaled aerosols.

Laughing in particular was found to create a greater disturbance. The researchers suggested that if an infected person were to laugh in an outdoor setting without a mask on, it could increase the risk of viral transmission.

(With inputs from The Hindustan Times)