Hack Chat Transcript, Part 1

A event log for PPE Testing Hack Chat

Breathing isn't as easy as it looks

Dan MaloneyDan Maloney 06/17/2020 at 20:050 Comments

Lex Kravitz11:46 AM

Lex Kravitz11:46 AM
Thanks for setting this up!

You bet. Thanks for suggesting it, and for your time today.

Lex Kravitz11:49 AM
You're welcome! I hope Hiram shows up, he's the one who actually knows about the testing procedures :)

William11:49 AM
Hi Lex, Hiram, did you get the email I sent to Dan?

Lex Kravitz11:50 AM
Yup, thanks for forwarding that info I think we'll start the chat with a discussion of that, and how these emergency adaptations are not FDA approved

William11:51 AM
I have been working with Ocean Reef Group, and using their APA adaptor for the Aria snorkel mask that you're showing here.

Lex Kravitz11:51 AM
Cool! Do you work in healthcare? Or medical devices?

William11:52 AM
I develop scientific equipment, I'm a PhD analytical chemist.

William11:53 AM
I have translated spectroscopy equipment to medical applications, and done in vivo human research at the University of Michigan Hospitals and at the VA.

Lex Kravitz11:53 AM
Cool I'm a neuroscientist but do a lot of 3D design and electronics work for our neuro experiments, and got in touch with Hiram back in March when he was looking for some help making scuba adapters for use in his radiology practice when they couldn't obtain adequate PPE due to shortages

William11:54 AM
Our group in Michigan tested out a couple of adaptors equivalent to the Pneumask and adaptors (simple mechanical adaptors from the snorkel mask to inline viral filters), and we found significant increases in CO2 in the inlet airspace compared to what we got when we used the mushroom-valve adaptor from Ocean Reef, so we discontinued our development project on the snorkel mask adaptors.

William11:55 AM
Have you guys tried the Ocean Reef APA adaptor in any of your testing? They have EN (european certifications) on their respirator solution, but haven't gotten the US CDC/NIOSH approvals for use in healthcare settings yet.

Lex Kravitz11:56 AM
Hiram did all of the testing, I'm not sure if he got the Ocean Reef adapter but he should be on the chat soon!

Hiram joined  the room.11:59 AM

William11:59 AM
The most complicated piece of this PPE is how so many people got feedback from FDA (CDRH) that the snorkel mask qualified as a face shield. But the snorkel masks are being used with air filters, which means they're respirators, and don't qualify under the FDA EUA as face shields, and instead need CDC NIOSH approvals.

Lex Kravitz12:00 PM
Hi Hiram!

Hiram12:00 PM
Hello, is this audio or just text

OK, looks like both Hiram and Lex are here, so let's get started. Welcome everyone, I'm Dan and I'll be moderating today. We have Lex Kravitz and Hiram Gay today to talk about testing for an emergency PPE they made.

Just text, Hiram.

Daren Schwenke12:01 PM
Only if you play Wargames.

Hiram12:01 PM

Daren Schwenke12:01 PM

Can we start out with a little about yourselves, Hiram and Lex?

Julie joined  the room.12:01 PM

@Daren Schwenke - Excellent classical reference

Lex Kravitz12:02 PM
Hi all! To give a quick introduction I am a neuroscientist at Washington University in St Louis, and I do a lot of 3D printing and electronics related to our neuroscience experiments. I was contacted by Dr. Hiram Gay in March to help with adapting scuba masks to be used as personal protective equipment PPE in his radiology clinic.

Hiram12:02 PM
My name is Hiram Gay, I am a radiation oncologist at WashU in St. Louis. Specialize in head and neck and prostate cancer

Nicolas Tremblay joined  the room.12:02 PM

Lex Kravitz12:03 PM
I can talk about the 3D design and some of out experiences there, Hiram can talk about the testing that we performed, and what it takes to test improvised solutions

Hiram12:04 PM
One of the satellite offices I direct treat between 20-50 patients a day. Each treatment course is from 1-44 days. Our therapists have a lot of patient exposure and can not social distance. This was the motivation for the snorkel project.

Lex Kravitz12:04 PM
We also did want to talk briefly about the issue of FDA approval - this is critical if a design is being distributed or sold for medical use. It is less of an issue for personal use, or in an emergency use situation in a medical clinic if FDA approved PPE isn't available, as happened in many facilities earlier this year

Lex Kravitz12:06 PM
There are many people working on adapting scuba masks for PPE. This project: has some good info on their experience with FDA approvals:

Joanna M joined  the room.12:07 PM

It makes sense when you think about it - physicians have always been able to use instruments of their own design to treat patients, right?

William12:07 PM
The Pneumask info is not up to date. FDA has clarified the position on the snorkel masks as being full face respirators.

The snorkel masks are not approved for use in healthcare settings by the FDA, because they don't qualify under the FDA EUA for face shields, or the FDA EUA for respirators (which only cover NIOSH-approved respirators).


William12:08 PM
EUA is emergency use authorization.

Gotcha, thanks

Lex Kravitz12:09 PM
Hiram do you want to comment on this? How does this work in your clinic, especially if FDA-approved respirators aren't available?

Hiram12:10 PM
Yes, especially in the surgical fields. Radiation Oncology is a more hands off type of specialty, so except in the area of brachytherapy (radioactive sources), we usually don't come up with devices. If you see, most of the snorkel mask ideas were born in anesthesia departments since this is a more natural transition

William12:10 PM
Sorry- here's the link to the FDA COVID-19 EUA's for PPE:

Hiram12:11 PM
In the beginning there was a a big PPE shortage. Now it has eased. I think the snorkel mask idea solved the need for a face shield and a filtration system. At our hospital eventually we were allowed to bring any home PPE, and this allowed us to deploy the snorkel mask

Hiram12:12 PM
FDA approval takes a lot of time. My understanding is it takes about $600 per device, and you may be required to test 10, so the costs add up if there is no private or corporation sponsorship

William12:15 PM
Respirator approval goes through CDC's NIOSH group. The manufacturer needs to be approved, and the specific respirator combinations (mask + filters) need to be approved. It's several thousand dollars in fees, and requires the manufacturer of the device to be approved and meed good manufacturing practice (GMP) standards.

Hiram12:15 PM
Full face snorkel masks require a fit factor of 500, while half-face masks including N95 masks require a fit factor of 100. It is very challenging to meet these requirements. the fit factor formula is: the ratio of the average chamber concentration to the concentration measured inside the respirator

William12:16 PM
They perform testing of 3 masks and 10 filters. The testing is performance testing with the respirator sealed to a test fixture that then measures how much particulate passes through the device.

Concentration of what? Is there a tracer particle of some sort?

William12:17 PM


Current Standard Testing Procedures for Air-Purifying Respirators | NPPTL | NIOSH | CDC

NPPTL Standard Respirator Testing Procedures, Air-Purifying Respirators

Read this on Cdc

Lex Kravitz12:17 PM
We posted info on our testing procedures and equipment here:

Joseph Stavitsky joined  the room.12:17 PM

Hiram12:17 PM
The key to success is having a qualified filter, in our case we used commercial 3M filters, and an airtight system (good seal around the face and putty to seal the 3D printed adapter Lex created

dannyvandenheuvel12:18 PM

dannyvandenheuvel12:18 PM
I know it's hard to get it medical proved, I made a respirator and still in process to get it on track

Hiram12:18 PM
You can do the test with the normal air particles in the air, but if the concentration is to low the PortaCount machine will let you know. With the machine you can get a particle generator which basically aerosolizes salt particles

OK, cool - thought it might have been a smoke generator or something.

Lex Kravitz12:19 PM
Early on we tried some HEPA filters from vacuum cleaners - we tried them out because they were easy to obtain when most other respirator filters were out of stock. However these did not work!

dannyvandenheuvel12:19 PM
I made it open source #DP Ventilator

Sophi Kravitz12:19 PM
Hi everyone! Sorry if this has already been asked, how many people have used the snorkel design?

Hiram12:20 PM
There is a qualitative (not quantitative test) that uses a pungent smoke, but it is still less rigorous than the PortaCount

Sophi Kravitz12:20 PM
I'm really curious to hear more about on-person testing and how you were able to iterate the 3D printed parts

Bharbour12:21 PM
Is the test using a "standard head" or a live person?

William12:21 PM have distributed almost 18000. have distributed another 23500.

Hiram12:21 PM
The one we designed is used by our therapists when we treat a patient suspected of COVID. SO far have not treated a COVID patient. We have 6 therapists, Other snorkel masks have been used across the country. The Pneumask project from Stanford was the most ambitious and rigorous

Joseph Stavitsky12:21 PM
So how is the situation right now with filters? How quickly are orders being filled?

Hiram12:21 PM
Testing is with a real person

Sophi Kravitz12:22 PM
How does testing work?

Sophi Kravitz12:23 PM
Does the person pretend like they have a breathing issue?

Lex Kravitz12:23 PM
I believe for healthcare facilities the filter supply has gotten much better. In March/April we couldn't buy respirator filters anywhere (except for marked up prices on eBay). One thing the manufacturers (mainly 3M and Honeywell) started doing was limiting private sales and prioritizing healthcare sale.

Hiram12:23 PM
I spent hours with the PortaCount and testing designs Lex created on myself. At first it was very frustrating because I could not get fit factors reliably above 100. Once we used the 3M filters and sealed the connection with the adapter, we got close to a commercial 3M mask

Joseph Stavitsky12:24 PM
So, what is a reasonable expected timeframe between ordering and shipping?

Lex Kravitz12:24 PM
@Joseph Stavitsky I haven't purchased respirator filters, but in my lab we are able to order other forms of PPE (gloves, masks) normally at this point. Like ~1 week including shipping. We order through healthcare channels though.

Hiram12:25 PM
The testing is standardized and lasts about 7 and a half minutes. I believe a shorter version of the test has been approved

William12:26 PM
Some filters have continued to be readily available throughout the crisis, such as the 22mm inline bacterial/viral filters.

Lex Kravitz12:26 PM
@Sophi Kravitz Hiram put info on the testing setup here: The person simulates several types of breathing and positions during the test

Hiram12:26 PM
Normal breathing

Deep breathing

Head side to side

Head up and down


Bending over

Normal breathing

Overall fit factor

Hiram12:26 PM
Above are the parts of the testing, missing is grimace

Sophi Kravitz12:27 PM

Sophi Kravitz12:27 PM
I suppose if you're having trouble breathing, grimace is going to happen

de∫hipu12:27 PM
grimace is inevitable

Hiram12:27 PM
Head up and down, bending over and talking are usually the weaker links that may result in failing the test

Hiram12:28 PM

Joseph Stavitsky12:28 PM
I currently have retail access to rubber gloves. I am planning a nonprofit to make masks and faceshields. Would it be possible for any of you to reach out to your medical contacts and get back to me with order wait times?

How does the face shield perform in terms of fogging? Every time I wear a mask or a respirator it fogs up my glasses something fierce. I'd imagine breathing onto the surface of the face shield would do the same.

Hiram12:29 PM can be a good source for filters and PPE

Joseph Stavitsky12:29 PM
And following up on Dan's point, is there a demonstrated benefit to covering the eyes?

William12:29 PM
Our nonprofit has been working on PPE (including getting regulatory approval) for the past 3 months. It's been a long grind.

Lex Kravitz12:30 PM
@Hiram related to Dan's question - were people in your clinic able to wear the scuba mask for long durations?

William12:30 PM
Yes, there has been a lot of research indicating a benefit to providing physical barrier protection like face shields or goggles, as well as respiratory protection against aerosols.

Joseph Stavitsky12:31 PM
@Hiram thanks for the link. Is there a specific model I should look at?

Hiram12:31 PM
The design of the OceanReef masks minimizes fogging. The air flows in such a way that it exits through a mouth valve or the filters. The mouth valve open won't protect patients if the user has COVID. The mouth valve can be sealed, but the mask is less comfortable and the humidity content will increase. Still you can see

Lex Kravitz12:31 PM
@William Thanks for your work with!

And I'd imagine there are a lot of things that radiation oncology techs handle that really don't belong in their eyes

Joseph Stavitsky12:32 PM
@william could you please point at some links for eye protection?

Hiram12:32 PM
The preprints of the project lists various filters

Hiram12:32 PM
In the coming week there should be a 3rd version of the manuscript and we will be submitting to a peer reviewed journal soon

Hiram12:33 PM
If you have access to a legit 3M full face mask, that is the way to go. It works very efficiently since the filters connect directly to the mouth compartment

Hiram12:34 PM
Eye protection could be anything from swim goggles, ski goggles, or as fancy as a full faced mask. There are many options out there

Hiram12:35 PM some masks

Lex Kravitz12:35 PM
Yes I think that's a big take-home here: these improvised solutions can be useful when the supply of commercial respirators isn't there, but if you can get a real respirator it will likely function better than anything improvised.

William12:35 PM
One of our collaborators has a company that specializes in snorkeling and scuba equipment. They have many goggles and snorkel masks (with adaptors) in stock:

Hiram12:36 PM this is another good website for PPE and filters

I was just looking at the offerings that Ocean Reef has. Snorkeling has changed a LOT since I was doing it back in the 80s

Lex Kravitz12:37 PM
haha @Dan Maloney I had that same thought when I saw the Ocean Reef site!

Hiram12:38 PM
CO2 rebreathing is a problem with some snorkel mask designs. Ocean reef minimizes this. We tested O2 saturation to verify this was not being compromised. Stanford did the tests in a more sophisticated way

Joseph Stavitsky12:39 PM
I mean, I get that commercial manufacturers are always going to be better but doesn't the current situation show that we need a logistics infrastructure in place when they can't meet demand?

Lex Kravitz12:39 PM
@Joseph Stavitsky Yes I think so!