Covid-19 transmission: Going to office, school, college again? Here’s why you must pay extra attention on ventilation

To reiterate, Coronavirus infection spreads via respiratory route and in order to minimise the risk of infection, there is need to pay attention when it comes to managing air flow in indoor spaces like classrooms, restaurants, homes, offices and neighbourhood grocery stores among others. If the person infected with Covid-19 speaks, laughs, shouts, coughs or sneezes, there is a high chance they would emit droplets that are carriers of the virus. The droplets, also known as aerosols, vary in size and can be large or less than a millimeter in diameter.

Small and intermediate size droplets can be a cause of concern as they remain suspended in air for a few minutes while the large droplets fall to ground due to gravity within 1-2 metres of the person who emitted them. During this time, suspended aerosols can be transported to distances for over 8 metres. This is precisely why there is a dire need of good ventilation.

To be sure, this is the reason why people have been advised to put on masks or even double masks for the smallest aerosols, so they do not enter the nasal cavity. N-95 masks have been considered for standard protection and surgical masks can also be used for prevention to a greater extent.

According to a study published in Journal of Internal Medicine, bars and restaurants have become the epicentre of multiple recent superspreading events. People when sitting in bars and restaurants do take their masks off, even for a short while to eat. Eating and drinking are some activities that usually take place indoors and in most cases, involve loud speaking. Due to this, bars and restaurants can be noted as the “epicentre of multiple recent superspreading events.” Now this has to be considered at a time when many states in India are opening public places with decline in Covid-19 cases.

For indoor settings, ventilation is usually poorer when compared to outdoor locations. The risk of infection is higher indoors. Therefore, a report by The IE noted that an average air exchange rate needs to be maintained. Rooms need to have exhaust ventilation with a higher fan rating. Also, pedestal fans should also be placed near doors or windows which can prove to be very effective. To be sure, ceiling fans just circulate the air in a room and they may not be capable of venting the aerosols out directly. For ventilation, doors and windows need to be kept open along with ceiling fans.

To put in perspective, ventilating a room allows dilution as well as removal of potentially infectious aerosols and can help in decreasing the risk of Covid-19 infection. Small, closed, air-conditioned rooms can result in enhancement of the risk. With the onset of monsoon season in the country, it is advisable to reduce the use of air-conditioning and leave doors, windows open that will ensure through-flow of air.

While the importance of ventilation is known, it’s time that the concept is used emphasized sufficiently in the country’s future strategy of fighting the Coronavirus pandemic. Needless to say, it’s safer outdoors. When sitting in an outdoor environment, the normal draughts of wind are believed to be enough to wither away infected aerosols and prevent transmission by diluting the concentration. Outdoor places with dense crowds like markets or urban train stations pose a threat of viral transmission since a large number of people are present in close proximity. In such scenarios, fitted masks or double masks are a must.