has not been tested. This device in no way is meant to replace existing
and approved masks and devices such as N95 mask and commercial PAPRs
when they are available. If you make this device or use the concepts of a
wearable powered HEPA filter you do so at your own risk. This device is
designed to be used as a 'crisis capacity strategy' for PPE as defined
by the CDC when the surge in demand for PPE leads to severe shortage or
unavailability of the approved protective equipment. As a physician I
have worn multiple types of N95 masks and PAPRs and I find our mask is
easy to use and breathe in. The HEPA filter should successfully filter
the coronavirus. Although distance between fibers in the HEPA filter is
0.3 microns and the corona virus is smaller at .12 microns in size, the
HEPA is able to filter close to 100% of coronavirus sized particles. The
HEPA filter accomplishes this based on the multiple methods of capture
the filter uses and the speed of which air is forced through the filter.
Almost counter intuitively, the slower the velocity of the air passing
through the filter, the more efficient the HEPA filter becomes at
removing even the smallest particles in the air. Although very
technical, the science behind this concept is illustrated [here](https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20170005166.pdf) in this scientific paper by NASA engineers.
We
like the use of the swim mask because it works as a face shield and
creates a 'airtight' seal around the face. In the event there is not a
complete seal, the positive pressure of the PAPR pushes air away from
the mask preventing outside particles from gaining access to inside the
mask. In addition those who have used a PAPR with the hood know how
difficult it is to hear inside the hood with the fan on. Our design
leaves the ears outside the mask for better hearing. Because of this
design, our mask can be used with a stethoscope, a feat that cannot be
accomplished with a traditional PAPR hood. The unit is also easily
deconstructed and the mask can be washed with soap and water and/or
appropriate cleanser and reused.
This project is a work in
progress and will most surely evolve, as does our fight with
coronavirus, and we will update the product design as we improve it. Any
suggestions or comments are welcome. We understand that this build
might not be for everyone as they may not be able to obtain the
necessary resources and or have the technical capability to manufacture
the device. For those who want to help in our fight I would like to
direct you to Team Shield. We have partnered with [Team Shield](https://teamshieldnorcal.squarespace.com/home) who are a an energetic group of students from Davis and Roseville
California that have come up with a surprisingly simple yet brilliant
solution to PPE equipment shortages. Their products and equipment are
currently in use at Northern California hospitals. Please check them
out because through Team Shield anyone can help our frontline healthcare
workers by making shields or making donations.
Also we are not alone in innovation in making PPE as a crisis strategy. Please read these excellent articles from [Make Magazine explaining how we ended up in crisis mode](https://makezine.com/2020/03/30/plan-c-crisis-mode-for-covid-19/) and a [second article showcasing makers](https://makezine.com/2020/03/27/make-these-projects-to-fight-covid-19-right-now/) around the world sharing innovation to help us all battle coronavirus.
As a physician I am not only humbled working next to my son in these
projects originally started as a way to protect me and my colleagues
facing crisis, but I am also humbled by the every-day makers and do-ers
with no ties to healthcare trying to find ways to help healthcare
workers and everyone else out of this mess we are in. We will survive,
not with the promises of our government and healthcare systems, but in
