Creating N-99 Masks for All Employees in the Middle of a PPE Shortage

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At Regenexx, we innovate, that’s what we do. However, these past two months we’ve had a problem. How can we keep our patients and employees safe? After all, physician offices are essential in the crisis and should be open. Hence, as an example of how we innovate, this is the story of how we made 3D printed N-99 masks for everyone in our Colorado office and for every Regenexx provider around the country who wants one.

The Problem

You’ve likely heard that we have a severe shortage of N-95 masks for front-line healthcare workers. The “95” means that the mask filters out 95% of all particles, including the small ones that float in the air after someone with COVID-19 coughs. However, physicians and staff who don’t work on the front-line in the emergency room, but who instead work in clinics also need these masks.

While you can find N-95 masks that used to sell for 50 cents for ridiculous prices online, every mask you buy takes one away from an ER doctor, a nurse in the ICU, or a paramedic who can’t control all aspects of their environment in the same way that we can in a private clinic. Hence, the idea of outfitting all of our employees with disposable masks that would rob thousands of units a month from that supply chain didn’t seem right. As a result, we needed a reusable N-95 mask that we could build that wouldn’t impact front-line health workers.

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A Solution?

A few weeks ago, my partner, John Schultz, M.D. sent me an email that was put out by a sales rep for a 3-D printer used in dental offices. The 3D file was for a reusable N-95 mask design. Intrigued, I hunted down several more 3D models online. Many of these involved cutting up large fiberglass HEPA filters for HVAC units, which I read could cause serious lung issues for the wearer. However, there was one design that looked like a winner. Someone in the 3-D printer community had redesigned the cut-up HEPA filter mask to use a series 700 Roomba HEPA filter. It turns out that the high-end robot vacuums like to clean your air as they do their thing. Some more online research showed that while this idea on its face sounded nutty, this could really work, as these HEPA filters were widely available, cheap, not made from fiberglass, and this option involved no dangerous cutting of air conditioner filters.

So John Schultz and I began working together to source a local professional 3-D printer company and I bought Roomba HEPA filters for about 90 cents apiece on Amazon. The pro-3D printer worked up a prototype, but the original design online didn’t really fit these cartridges well. In addition, the prototype was of a hard material that was going to be tough to wear all day. Hence, we opted for a rubber-type material and our 3-D printer professional made some edits to the 3D file to get the Roomba cartridges to fit tightly.

Prototypes and Final

The original second-generation prototypes were black, which was pretty off-putting (Darth Vader-esque). Hence, we finally went with medical white. The final product is below (story in the video above):

The Smoke Test

OSHA has a fit test that they use for healthcare workers and others that wear these respirators all day. They use a few different substances, but by far the most noxious of these is a chemical “smoke” irritant made from Stannic Chloride. You basically have a glass ampule where you break open both ends and the air causes the chemical reaction. You place this ampule on one the end of a rubber bulb and push smoke out of the other. How do you know it’s working? I got a small whiff of this stuff and immediately began violently coughing. Hence, if you can expose the person wearing the respirator to the chemical smoke and have them not react, the respirator is working well. That’s in the video above towards the end where you see Dr. Schultz wearing the swim goggles to protect his eyes.

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N-99 vs. N-95

HEPA filters are technically N-99 in that they remove 99% of the particles in the air down to 0.3 microns. Given that the small water droplets that hang in the air and contain the virus are in the 1-5 micron range, either N-95 or N-99 will work. However, because these masks use HEPA filters, they are classified as the higher rated N-99.

What Else We’re Doing

Every Regenexx clinic is going above and beyond to protect patients. This is what we’re doing in our Colorado HQ clinic:

Also, if you’re more comfortable staying at home and getting a new patient evaluation or follow-up that’s covered by insurance by using your computer, tablet, or smartphone, we have developed an entire Telemedicine system that allows you to watch a video on self-exam and fill out a form for your Regenexx physician. We have super-specialist physicians standing by all around the country to get you seen:

The upshot? We’ve been working overtime these past few weeks to innovate! We’re also supporting the front-line healthcare workers by reducing our PPE usage as we open our clinics back up to begin to perform elective procedures again!

[If you know a front-line healthcare worker that still can’t get a daily supply of N-95 masks, reach out to us in the Blog comments and I would be happy to supply them the name of our local 3D printer who has these files and who can print these in small, medium, or large. The mask can be made for about $45 and uses 90 cent HEPA cartridges that should last at least a week or more. It can also be sterilized daily with medical grade disinfectants. We don’t make anything off these masks, that’s the 3D printer’s price, so you will pay him directly!

Contact Info to get a mask printed:

Nick Yosha | VP of Sales and Marketing
3D Printing Colorado |
6901 West 117th Avenue, Unit 4 | Broomfield, Colorado 80020
303-466-0900 | [email protected]]

Chris Centeno, MD is a specialist in regenerative medicine and the new field of Interventional Orthopedics. Centeno pioneered orthopedic stem cell procedures in 2005 and is responsible for a large amount of the published research on stem cell use for orthopedic applications. View Profile

If you have questions or comments about this blog post, please email us at [email protected]

NOTE: This blog post provides general information to help the reader better understand regenerative medicine, musculoskeletal health, and related subjects. All content provided in this blog, website, or any linked materials, including text, graphics, images, patient profiles, outcomes, and information, are not intended and should not be considered or used as a substitute for medical advice, diagnosis, or treatment. Please always consult with a professional and certified healthcare provider to discuss if a treatment is right for you.

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