India: Ventilation is the key to combat Covid, experts explain

Mumbai - Poorly ventilated and closed offices or other facilities and crowded places ensure the transmission of the coronavirus.

With the reopening of restaurants, malls, gyms, offices, railway and metro networks, bus services and other public facilities in cities across India, there is growing realisation on the importance of ventilation to prevent Covid-19 transmission.

Poorly ventilated and closed offices or other facilities and crowded places ensure the transmission of the coronavirus. “To minimise the risk of infection, we must pay attention to the flow of air in indoor spaces such as homes, classrooms, restaurants, offices and grocery stores,” say a group of experts led by Guruswamy Kumaraswamy, professor of chemical engineering, IIT-Bombay.

According to them, crowded places such as railway stations or markets pose a higher risk for the transmission. “As India opens up, physical distancing will not always be possible,” they point out in an article published in a newspaper on Thursday. “There will be times when we will need to come into contact with people in closed rooms, in cafeterias, offices, or in social settings. An often-neglected fact is that even talking can spread Covid-19; our research shows that short, unmasked conversations can carry a significant risk of infection.”

Stressing on the importance of ventilation, the authors note that ventilating a room dilutes and removes potentially infectious aerosols, decreasing the risk of infection. “Well-ventilated airy rooms with open doors and windows reduce the risk of infection,” they note.

But specific parts of the room such as corners have pockets of air that form recirculating zones. “Pathogens trapped in these zones are not easily vented out. Our simulations indicate that droplets in these regions can stay for 10 times longer than in well-ventilated parts of the room. A person sitting in a recirculating zone will be more exposed to infectious pathogen, thus increasing the risk of infection,” the authors point out.

Small, closed, air-conditioned rooms carry an enhanced risk. With the onset of the monsoon season, it may be feasible to reduce the use of air-conditioning, leaving doors and windows open, ensuring that these spaces sustain a through-flow of air and that zones of recirculation are avoided, they note.

“The role of ventilation in ensuring safety against the transmission of Covid-19 has not been emphasised sufficiently so far, but should be a crucial part of India’s future strategy,” the authors say.