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How to Protect Yourself from the Aerosol Spread of Covid-19

posted by Jason Kottke   Oct 02, 2020

A group of scientists who believe that WHO and the CDC are being too slow in acknowledging the role of aerosol transmission in spreading Covid-19 have written up a Google Doc of advice for the public: FAQs on Protecting Yourself from COVID-19 Aerosol Transmission.

The goal of these FAQs is to provide information to the general public in an efficient manner about how to prevent aerosol transmission of COVID-19, with the hope that this will allow more informed decision making by individuals or organizations. All of this information has been posted in Twitter and other forums, but can be difficult to find. Having multiple experts working together, and having the ability to update this information also improves its quality. These FAQs represent our best understanding at this time, and should always be similar or more stringent than information provided by CDC, WHO, and most regional & local health authorities. If your authority has a more stringent guideline than discussed here, follow that more stringent guideline.

The group was organized by chemist Jose-Luis Jimenez, who has been studying aerosols for 20 years. You may remember Jimenez from his excellent piece in Time magazine, where he used the analogy of smoke to explain aerosol transmission. Here’s a snippet from the FAQ, highlighting something I’ve been concerned about lately: people wearing face shields instead of masks and employees in stores not wearing masks behind plexiglass shields:

7.13. Are face shields and masks interchangeable?
No, face shields do not offer much protection against aerosols (also see this video), while masks do. Face shields are good for blocking ballistic droplets released by the wearer or that might fly into the wearer’s face when close to others. Face shields are considered a supplement to masks for partial eye protection (but less useful than closed glasses, as discussed above), but not a substitute for them.

7.14. Are plexiglass barriers helpful?
Plexiglass barriers are generally useful to avoid direct droplet infection and direct aerosol transmission whenever people are in close proximity and distance cannot be kept. Therefore, it is recommended to use them as a direct transmission suppression tool at such places, such as a supermarket checkout.

However, as aerosols follow the air movements indoors, the protective effects of the plexiglas barriers against aerosols will be limited. Plexiglas barriers alone are not a sufficient approach to protect against aerosol transmission. Their installation alone cannot protect against indoor aerosol transmission and should not be regarded as safe and sufficient protection.

MIT Technology Review’s Charlotte Jee interviewed Jimenez about the FAQ document.

We update the document all the time. We’re effectively having to be a little WHO or CDC. We’re saying the things that they should be saying. This is frustrating, but it’s the situation we find ourselves in. These organizations have been flat-out refusing to consider if aerosol transmission is important, which leaves people unprotected. So we feel it’s our duty to communicate directly with the public.

Right now, in my opinion as someone who has done a ton of reading about Covid-19, the most best accessible information on how individuals and societies can protect themselves and others during the pandemic (and why) is available in Jimenez’s Time article, Aaron Carroll’s NY Times piece about how to think about risk management, Zeynep Tufekci’s piece in the Atlantic about dispersion and superspreading, and now this Google Doc by Jimenez et al.