by Thomas B. Cross – Executive Director Pandemic Tech Alliance
Among the many great Einstein sayings comes this, “if you can’t explain it simply, you don’t understand it well enough.” Nowadays a more common saying is “keep it simple stupid” or KISS.
What is a simple way to minimize virus spread in an enclosed area? Simple, open a window.
The challenges to doing so are outside weather, security and windows which do not open. Warehouses and meatpacking plants likely don’t even have windows or nearby doors. High-rise buildings likely do not have windows that open or doors to the outside.
To keep occupants from potentially getting infected, you need to make sure the fresh air is blowing rather hard into your store, office or home.
For those of you inside buildings with inoperable windows, you can now start screaming at me using the f-word. In this situation, simply work from home. If you can’t do that, stop screaming at me for a minute and try to talk to the air handling department for guidance regarding this and share the link to this article.
There is also a report in Msystems that says – “Viruses are frequently found associated with larger particles (e.g., complexes with water, proteins, salts, etc.) in a range of sizes. Even though some of these particles have been identified in sizes that could potentially penetrate high-efficiency filters, ventilation and filtration (FFF) remain important in reducing the transmission potential of SARS-CoV-2.”
This is a nice way of saying even the experts don’t know enough and frankly every building, home, or store is completely different so the idea of one solution for all is also ridiculous but good FFF and DDD (below) just might keep you safe.
Negative Air Pressure
The report and other sources explore the benefits of negative air pressure systems. As Einstein might say, “air comes in from the top and is sucked out the bottom.” See figure below. However, the hard part is that you would likely need to rebuild your building to accomplish this so you can go back to screaming at me.
Bottom-line – Like with cybersecurity, you are never safe, nor ever safe with real viruses either. Protect yourself and others – remember DDD – Distance – Dose – Duration
- Increase distance to 10+ feet or more.
- Reduce dose by wearing a shield/mast.
- Reduce duration to less than 10 minutes.
Background Research
CBS News put out a good story on air handling mainly about restaurants but no discussion of offices or all the other BE or built-environments that exist. The report shows a model of how coronavirus can spread farther than 6 feet.
Look at how the air flows below and imagine that breathing, speaking, and coughing have escalating viral shed quantities. The resulting viral “plume” travels from one person to everyone else.
The CBS news reports also refers to an American Society of Microbiology paper which covers a lot of details. Called 2019 Novel Coronavirus (COVID-19) Pandemic: Built Environment Considerations To Reduce Transmission, it is specifically related to air handling. Here are some details and benefits of using a negative pressure system shown below.
The diagram above represents the ideal airflow to keep viral shedding between occupants to a minimum. Even if the virus is passed between people, the idea is the viral load is sufficiently reduced as airflow is directed downward with significant force.
These are some ideas to keep in mind as you continue to, or return to, work. In order to have safe environments for customers and workers, we need to reimagine our buildings, offices and workspaces.
