Rocket Science: Air to Breathe

Better air quality is possible, but this needs some improvement in closed spaces.

Dear readers,

Today we are again dealing with the topic aerosols and how to protect yourself. It is not rocket science!

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Three observations, we repeatedly make:

A business is showing a poster at the entrance pointing to face masks being mandatory. This, we think makes sense. However, personnel are not wearing masks. Masks (usually simple medical masks) are donned in a flurry once customers are entering. This behavior is thwarting all precautionary measures to keep the virus at bay. Upon pointing out that these people are endangering themselves, the justification we hear is something along the line of “once in a while I like to breathe”. There is one – never mentioned – positive side effect of wearing N95 masks: In a business located next to a street with heavy traffic, the air you breathe through an N95 mask is a lot cleaner than without a mask.

Some businesses had installed plexiglass shields at the counters. These are a nice protection from spitting, but they do not help against aerosols. Cashiers who do not wear an N95 mask, are acting stupidly.

We are avoiding such places like the plague.

Even at temperatures above 15 °C there is NO ventilation. Where is the problem? Upon asking, we usually get replies such as “we have the assignment to open a window for five minutes once an hour”, or another classic “all windows were open right before you entered”.

There is one thing these people do not comprehend:

Unfortunately, SARS-CoV-2 has got the propensity to also be transmitted by aerosols. In closed spaces especially, this is leading to high virus concentrations in the air. Therefore, in such situations, keeping a distance and wearing a face mask are not sufficient.

A constant airflow is necessary.

Reports from classrooms or open-plan offices, where once an hour one window is being opened, are bringing us to the brink of a nervous breakdown.

There are two options here: A constant airflow across a room, enabling a regular air exchange. Alternatively, installation of an air condition that actively exchanges the air several times an hour. All this is feasible. Why is this not being implemented? Creating an airflow is easy.

The German government is funding lignite production. This money could be used in a better way.

To all those who want to know more about the benefits of air exchange in closed spaces, we want to recommend the following demonstration in the New York Times. It is picturing the results of a recent study by the Harvard University and their cooperation partners. It is illustrating very vividly why a regular (and correctly installed) air flow is necessary. This should be very instructive to teachers especially since they are working in a cramped space with too many people for hours a day.

From a study by the Harvard University, three exemplary situations are depicted. An opened window does dilute virus load, but not good enough to be protective. Only a directed air flow is having a significant effect on virus density.


What is the situation with one infected person spreading virus in a closed room?

Figure 1: One infected person, all windows are closed. The virus density in the air flow is shown (the darker the color, the higher the density).
Figure 2: Same situation as in Figure 1, illustrated in a different way. Virus density is shown on differen levels (the darker the color, the higher the virus density).

Figures 1 and 2 are showing the constant circulation and accumulation of contaminated air in a closed space.

What is the situation with one open window?

Figure 3: One infected person in the room, one window open. Virus density in the air flow is shown (the darker the color, the higher the density). The window is reducing virus density, but a significant amount of virus remains. Thus: One single open window is NOT enough!

What is the situation with one air cleaner and a fan blowing air from the outside into the room?

Figure 4: One infectoed person in the room, air cleaner and fan (blowing in) are installed. Airflow shown as in previous figures. This indicates that a fan needs to blow from the inside out to have a positive effect.

Bottom line: Airflow needs do go across the room, that means windows need to be open on two sides of the room.

Air cleaners and fans need to be installed correctly, resulting in an airflow from the inside out.

This is giving us the opportunity to point out that the reputable American periodicals (such as Washington Post, New York Times, The Atlantic among others) are making any content dealing with the COVID-19 pandemic freely available online without any subscription. This, we are missing with the German outlets.

Even now, there are ads for face shields. These face shields are fine for protection of your face and eyes from spit. They do not, however, protect from aerosols (!), neither you nor the person facing you. When wearing such shields, it is imperative to also don an N95 mask. Anything else is just a sham.

Most people are wearing a simple medical mask, in most cases not adjusted correctly, or over a full beard. It is not surprising that infection numbers are increasing sharply after lifting the measures. In Germany, we are facing exponential growth of infection numbers already now. Last week, 70,000 new infections were reported, this week we shall see more than 90,000.

Please inform yourself consulting trustworthy sources (you are reading one just now). Please, keep learning, please remember that it is not necessary to do all the things that are not outright forbidden. Use your common sense: Do I really need to enter a closed space cramped with people? Are these really 6 feet distance, or a mere 2 feet? Am I really having trouble to breathe wearing a face mask? Do I really need to hit the pedestrian zone on the day all businesses are reopening? This is called prioritization. With some exercise, it is easy.

The German economy has been moaning for months now. However, what may the economy do to protect their employees and their customers from infection? Ensuring fresh air in closed spaces would be a start. It is so easy.

Yours, Sabine and Jörg

SAJO is consulting all around infectious diseases. We are applying our know-how, that we have acquired in more than 20 years. We do what we can to fight this pandemic.

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This is our post No. 160. To our delight our blog is receiving a lot of acceptance, we love to share our knowledge. Single posts and contents are being adopted by others, also in media. We have learned how to correctly make a citation; this we would wish from others in return as well. Please feel free to share the link – it is an informative tool to fight this pandemic.

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