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We have heard that ventilation and improving air quality is important during the pandemic.
But is it true? How much does it help, really?
The importance of ventilation
If you spend ten minutes in a closed room with someone infected, the viral concentration in the air might slowly build up to very dangerous levels. Conversely, if you spend time in a well-aerated room with someone infected, the concentration of the virus in the air might remain low even as the other person keeps sneezing (because most of the virus exits the room as the air is replaced).
Ventilation is useful because it reduces the quantity of virus particles in the air.
This might not seem important to those who believe that spending time in a room with a low viral concentration represents the same infection risk as spending time in a room with a high virus concentration. However, in fact, higher viral concentrations in the air represent both a higher risk of infection and, if infection does happen, a higher risk of severe outcomes.
You can think about it as if your body were a country invaded by enemy soldiers (the virus). How many soldiers invade surely influences the chance of success of the invasion and how much devastation it causes.
Ventilation and other precautions
Ventilation also has a critical role in improving the effectiveness of other precautions.
For example, social distancing is rather useless if you sit in a poorly-ventilated restaurant room a few meters away from someone infected. This is because, earlier or later, the virus exhaled by the infected person will fill the room. However, if the room is well-ventilated, social distancing might be quite effective. Most of the virus might exit through the windows instead of traveling to your nose.
Think about smoking. If you sit at a poorly-ventilated restaurant and there’s a smoker sitting a few meters away from you, your clothes might smell of cigarettes – but less than the clothes of the person sitting next to the smoker. However, if the restaurant is well-ventilated, your clothes might not smell like cigarettes at all, whereas the clothes of the person next to the smoker will still smell like smoke, though less than in the scenario with no ventilation.
Similarly, masks work better in well-ventilated rooms. Immune systems work better in well-ventilated rooms. Not in the sense that the mask or immune system act differently – simply, they will have fewer virus particles to “fight.” Therefore, the chances that a significant number of them slip through our defenses will be lower.
How to improve air quality
Here are a few options to improve air quality:
– Ventilate by opening windows.
– Mechanical ventilation (making sure that the air flowing inside the room is clean, as opposed to it coming unfiltered from another room, which might contain infected people).
– Air purifiers (they are cheaper than commonly believed, with the so-called Corsi-Rosenthal Boxes starting at less than $100).
If you need to make sure that air quality is great, you might have to get professional advice on how to ventilate your room correctly. However, this shouldn’t stop you from just doing your best to ventilate as much as possible and perhaps buy an air purifier – any ventilation is better than no ventilation (again, with the possible exception of mechanical ventilation that might draw infected air in).
How to track air quality
Measuring carbon dioxide concentration (CO2) is a relatively good proxy for air quality – if a room has high CO2 concentration, it is inadequately ventilated for the people it contains.
Conclusions
Improving air quality is important to reduce both the chances and severity of infection.
The better ventilated indoor environments are, the less risky they are, and therefore, fewer additional precautions will be needed to keep risk relatively low (such as masking).
Air quality is probably our best option to make indoor activities safer without inconveniencing the participants. Therefore, it should be widely supported, especially by those who dislike alternatives such as masks or lockdowns.
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