Hello Andy, Thank you for your thoughtful reply. While the use of masks without a N95 fit tested quality do not prevent airborne pathogens such Covid 19, a disposable mask that does not retain the moisture as a cotton material mask would be a better droplet precaution barrier than no mask at all. Of course, this is theoretical, as a randomized control trial would be unethical. While your explanation of fluid dynamics is correct, the purpose of a non-N95 mask is for droplet precautions rather than airborne precautions. By no means am I promoting use of such non-fitted masks to allow general public interaction. Rather, consider it an option for necessary public outings, such as getting groceries, toilet paper, delivering items to home bound residents, etc. As for subpar ppe, I agree that it is dangerous, and the lack of appropriate supply for healthcare professionals is of grave concern. There is a national shortage of N95 masks for this pandemic, and HC professionals are resorting to use droplet precautions only as N95s are being "saved" for use when the surge amplifies. These non-N95, non-fitted surgical masks are also not of unlimited quantity. If businesses not deemed a critical industry help divert standarized quality surgical masks to HC professionals as well as others in a critical infrusture industry (police, firemen, sewage/waste/utility personnel...), then less masks that offer droplet barriers are available to the general public. Thus, there is a definite need for the DIY masks for the general public to use when necessary outings are made. Lastly, I strongly recommend sheltering in place, but if you must leave, do take precautions. - Junwen Law, MD On Tue, Mar 24, 2020, 11:30 asc pgh <asc.pgh@gmail.com> wrote:

You may attain N-95 filtration specification but have you provided for seals around the margins of the mask with your face?

Tighter filtration creates higher inspiratory and expiratory pressures to pass through the filter matrix and these pressures will find the easiest route, which is NOT through the filtering matrix of a mask without adequate seals. Leakage is unfiltered, period. Not better than nothing, just equal to it. N-95 masks in healthcare are fit tested to individuals and donned under direct observation. Facial hair (beyond trim moustaches) eliminates any possibility of any benefit of any mask by preventing a seal.

Subpar PPE is dangerous. If you assume the risk, that's understandable for you, but with the latency of COVID-19 symptoms after being infected and contagious, you will hazard the entire community by using such a mask to leave the shelter of home if believing that some degree of protection has been afforded. The king really isn't wearing any clothes in this case.

Please, if you wouldn't leave your home without a mask, for yourself and the rest of us, don't leave your home wearing a homemade one.

Andy

On Tue, Mar 24, 2020 at 10:23 AM Junwen Law <junwenlaw@gmail.com> wrote:

...

Consider making masks with an ultrafine Hepa filter (deconstruct a furnace filter) While not as effective as a N95, would be better than no mask or cotton material.

Junwen

On Sun, Mar 22, 2020 at 2:56 PM Lauren Sims <lauren.sims03@gmail.com> wrote:

...

*"Charity is giving people what they need to get instead of what you want to give."*

The urge to help in times of crisis is powerful and wonderful. If a health care worker directly requests a homemade face mask, *make her one by all means.* *However, be aware that many health care workers in our area are actively avoiding homemade cloth masks. *Don't be offended. Here's the reason why:

A cluster randomised trial of cloth masks compared with medical masks in healthcare workers <https://bmjopen.bmj.com/content/5/4/e006577>

"Laboratory tests showed the penetration of particles through the cloth masks to be very high *(97%)* compared with medical masks (44%) (used in trial) and 3M 9320 N95 (<0.01%), 3M Vflex 9105 N95 (0.1%).... *The physical properties of a cloth mask, reuse, the frequency and effectiveness of cleaning, and increased moisture retention, may potentially increase the infection risk for HCWs.* The virus may survive on the surface of the facemasks,29 <https://bmjopen.bmj.com/content/5/4/e006577#ref-29> and modelling studies have quantified the contamination levels of masks.30 <https://bmjopen.bmj.com/content/5/4/e006577#ref-30> ."

*Instead, here are three ideas that will help give a boost to ALL health care workers:*

1) If you can, give blood! https://www.vitalant.org/Home.aspx

2) Pool your resources with friends to support health care workers AND your local restaurants at the same time: order takeout for 20-30 people to be sent to your neighborhood hospital.

3) Follow Valerie Sweeney's lead in her email "Medical professionals and PPE" and try some local advocacy to help track down medically approved personal protective equipment.

*Thank you for being great neighbors.*

Lauren