Watch| WHO Expert Explains the Role Ventilation During COVID-19

The World Health Organisation's weekly show Science in 5 brings together some of the biggest scientists, experts and doctors who are working on the coronavirus to educate on the various aspects of the disease, the pandemic, vaccines and treatments.

The show is hosted by WHO's head of strategy, department of communications, Vismita Gupta-Smith. Do listen to Dr Maria Neira, WHO Director, Department of Public Health, Environment and Social Determinants of Health, who explains the role that ventilation plays in keeping indoor spaces safe from COVID-19

How important is ventilation and how does it make indoor spaces safe from COVID-19?

Ventilation represents a very important aspect, a very important factor to prevent the virus from spreading indoors. So, something as simple as natural ventilation means opening the doors, opening the windows, can provide this type of removal of the healthy air we want to breathe. And let me give you an example. Whenever it’s possible in public spaces or in buildings, ensure a natural ventilation, opening the windows. And, in in settings like schools or work places or tourist places, what we are recommending is to increase the rate of air change, increase the rate of ventilation by natural ways or mechanical ones, always try to avoid the recirculation of the air. And when you cannot avoid it, then having filters that are  properly and regularly maintained and changed as needed. Please don’t forget that ventilation is very important but it’s not the only measure. So this has to be an intervention part of a package. of interventions to prevent COVID-19 from being spread.

How can we be sure that enough outdoor air is circulating indoors?

Of course, we need to consider the space size. I mean, how big is the room or the space we want to ventilate, the occupancy rate, how many people are occupying that room and the activities that are carried out in that space. And, of course, there are formulas to calculate all of that but essentially what we know is to renew the air. To give you an example, if in one hour you renew, you change your air six times, I think that will provide quite a sensible way of making sure that we are reducing or preventing the spread of the virus indoors.

It is not always possible in heavily-polluted places to open doors and windows. How should we manage outdoor air pollution, preventing that as well as preventing COVID-19 and keeping our houses better ventilated?

Together with COVID-19, we very much are concerned by air pollution and as you know, this is a major public health issue still responsible for 7 million premature deaths every year.  So, my answer will be, we do whatever is needed to reduce air pollution outdoors by putting in place the different measures and interventions that are available and requesting the authorities to do so. But while this is not possible, we need to make sure that we still ensure some natural ventilation, except, of course, if you are very close to the source of emission or there are very heavy and very high levels of pollution. But in any case, you can consider as well, depending on your capacity of where you live, you can consider what they call air purifiers,  and of course the HEPA filters, that in some residential buildings are already available