Efficacy of Face Shields Against Cough Aerosol Droplets from a Cough Simulator

When healtlhcare workers are caring for patients
with things like respiratory infections one of the things that is recommended in the isolation
precautions is that they wear like a face shield or goggles or something to help protect
the face. It turns out though, there has been a lot of work looking at how well face shields
protect against things like blood splatter or you know during dental procedures and that
kinda thing. But previously no one had looked at face shields in terms of how well they
protect against coughs and the kinds of aerosols people product when they’re coughing while
they’re sick. So the purpose of this project was to look at that. We were actually asked
to take a look at face shields in the context of a coughing patient just get a sense of
how much protection they actually offer and what they will and what they won’t do. This was the first time anyone had actually
looked at faceshields and how well faceshields protected healthcare workers when you’ve
got a patient that’s coughing. The other unique thing about the study is at NIOSH we
have a room, a simulated medical examination room. In that room we have a machine that
coughs and a machine that breathes. So what we can do is we can actually simulate a healthcare
worker that is in a room caring for a patient while the patient is in that room coughing
out what might be a infectious aerosol, a lot of infectious particles and that type of thing. What we found was when a patient coughs what
you get initially is you get kinda this burst of aerosol, this intense cloud of aerosol
that comes out. And if the healthcare worker is close to the patient that can hit them
in the face and you get this very intense exposure. We found the faceshield was really
good at blocking that initial exposure. That it tended to take those cough particles and
either they would collect in the faceshield, they would hit the face shield and stay there
or they would get diverted around the face. So they did a really good job at that. And
in terms of things like large droplets they did a really good job at catching those or
blocking those from hitting the face. But what we also found was over time the big droplets
from a cough would tend to fall to the ground. But the small stuff will sit in the air and
kinda keep swirling around and over time what can happen is the small particles will come
around the face shield and be inhaled by the worker. So the faceshield does a really good
job against big drops and does a really good job against that initial burst but it doesn’t
really protect you very well against smaller particles. With something like that you really
need something like a respirator. A face shield is a really good addition to
something like a respirator. If a worker needs protection against small airborne particles
like if they’ve got a patient that’s got tuberculosis or during something like a influenza
pandemic a worker really needs to wear some kind of respiratory protection but a face
shield over top of that will help protect the face and help protect the eyes and also
it helps keep the surface of the respirator itself cleaner so it helps keep you know helps
keep the worker from possibly contaminating their hands later when they are trying to
take their respirator off. So face shields are really good for what they do they are
a really good addition to a respirator but they shouldn’t be considered to be a substitute.