Answering Your Questions About PPE

Stan Bunger
May 14, 2020 - 1:17 pm

As we continue to navigate these unprecedented times, KCBS Radio is getting the answers to your questions about the coronavirus pandemic. Every morning at 9:20 a.m. Monday-Friday we're doing an "Ask An Expert" segment with a focus on a different aspect of this situation each day.

Today we’re looking at all the different types of personal protective equipment now in use with Dr. Michael Edmond, chief quality officer, associate chief medical officer and clinical professor of infectious diseases at the University of Iowa Hospitals & Clinics.

You and some of your colleagues have done a lot of work around various aspects of protective gear and clothing in the hospital environment. But as everybody begins to figure out how to restart the economy, people are going to be wearing stuff they may never have been around before. One of the things that intrigued us was this notion of face shields. Can you talk a little about what those are? Let's define terms a bit here first.

So face shields are essentially a very simple protective device that has two components. One is a clear plastic part that covers your face. Typically the best ones would go below your chin on the front and then to your ears on the side. And then they're affixed to some type of headpiece, like a headband, that keeps the entire thing attached to your body.

And are these worn instead of or in addition to some kind of a face covering, a mask?

Well it depends. In the hospital setting it might be different than in community settings. So we got very interested in face shields because as we started to see patients with COVID, we looked at our inventory of all the personal protective equipment that you would need and saw that we were probably going to face a shortage of medical face masks. So we needed to preserve those face masks for people that were actually caring for COVID. So we started to use face shields and we learned a lot about face shields in a pretty short period of time.

The face shields were deployed; we have more than 10,000 people who take care of patients in our hospitals. Every one of our healthcare workers has been issued a face shield and they wear them every day. Subsequently we were able to get more masks to have a better supply, and the CDC also recommended later that all healthcare workers should have masks on when they're inside the hospitals as well. So now all of our healthcare workers have on shields and a medical grade face mask.

As we thought more about face shields and became more comfortable wearing them in the hospital, we began to think about whether these would be good devices for people to have in the community as well. And part of the reason is that they have a lot of advantages that face masks don't have and the medical grade face masks are still in relatively short supply. It's difficult for people in the general public to get them. But actually, face shields are not too hard to get. So we're able to get them and I think they have lots of advantages. So I think it's something for the general public really to start thinking about.

So doctor, let's get going on the questions that have been sent in by our listeners to askus@kcbsradio.com

Are the face masks used by firefighters against wildfires effective in this model?

I don't know the type of masks they wear so I can't say. If there are some industrial type respirators, that can be used to protect yourself but I don't know exactly the model that these guys are wearing.

Could I just use something like the shields they sell at construction-supply outlets? Or does it have to be something specialized for the medical profession?

No, in fact it's very difficult to find shields that are marketed towards medical uses. Those are all in short supply. And that's part of the beauty of face shields, that they're using in many different industries and so the supply chain is much more robust.

So all the face shields that we use in the hospital actually were designed for things like woodworking and metal grinding. A lot of people who do a lot of that kind of stuff may even have one of these in their own home, and these are fine to use. The nice thing about them is they're sturdy too.

One of the advantages of the face shield, unlike a mask we wear in the hospital is it's reusable, it's durable. You can just wipe it off, you can clean it with soap and water or any kind of household disinfectant that you have. It's a device that will last you a long time as opposed to a paper face mask that you might get through a day or two with.

This would be something to keep the wearer from being hit with droplets, right?

That's right. And we believe that for this particular disease, most of the transmission appears to be occurring via droplets. And we all produce droplets. When you talk or cough or sneeze or laugh or sing, you're producing droplets. And in general most of these droplets don't go much more than six feet, which is why you see all the social distancing messaging saying to keep six feet between you and other people. But what these shields do is they catch the droplets that would have landed on your eyes, your nose, in your mouth - and those are the three areas of the body where the virus gets in. So by having those covered, we can reduce transmission to a great degree.

Now one of the things you have to keep in mind is you can still get the virus on your hands. So if you were to touch a tabletop that has virus on it, where somebody had just coughed, and you touch your nose or mouth or eyes, you could infect yourself with the virus. So face shields, face masks, whatever face coverings you're talking about - we still have to worry about people infecting themselves. And that's why washing your hands is still so critical.

We've seen lots of news coverage from Asia and Europe and it seems these clear face shields are pretty common for people working in stores and bus stations. Do they know something we don't? Are there standards for those shields?

I think they probably do know something we don't. It's interesting, I have a friend who's a physician who works in Vietnam and she's sent me a lot of photographs of being in the grocery store where everybody has face shields on. So yes, I think there are countries that have moved on to face shields a lot sooner than we have.

In terms of standards for them, basically these are very simple devices. So just a couple of things I think you want to look for when you purchase one. One is, as I mentioned earlier, it should come down at least to the level of your chin and it should, on the sides, go back about to your ears. And then the other important thing is at the top, it shouldn't be open. So there shouldn't be a space between your forehead and the shield where droplets can go down through and get on your eyes and your nose. And a lot of face shields are constructed so that that top gap is covered, so you want to look for one where there's no gap between your forehead and the actual plastic.

Some kind of a browband?

Yes, exactly.

I am claustrophobic and unable to wear a face mask. I have tried a number of them made from different materials without success. I did buy a baseball cap with a shield attached to it so I can breathe normally. This has enabled me to go outside and take care of simple needs. The shield covers/extends from just above the brim of the baseball hat to below my neck/throat area. I’m sure that this is a safe way to be outside and still maintain a safe distance from other folks. Is this right?

From the description it sounds pretty good, yes. I think that's okay. As long as the shield is long enough and it's giving you good coverage, I think that should be fine.

The next question goes back to the masks we're being asked to wear to keep from infecting others: I see many folks on TV wearing masks covering their month but not their nose. I think both should be covered. Please comment.

They're absolutely correct. As much as we're pushing masks for people in the community, we see lots of them not wearing them correctly. So what is correct? They need to cover the mouth and the nose, so you can't pull them down. The other thing is you don't want to touch them once you put them on because the mask itself may become contaminated on the exterior surface, so you don't want to touch that. You want to touch them as infrequently as possible.

One of the downsides of masks is that many people who wear a mask touch their face more. Sometimes they itch, sometimes they're just bothered by them or they're trying to adjust them onto their face. And touching your face is something you definitely don't want to do because if there's virus on your hand, you're going to infect yourself. And that's another great advantage of the face shield: you can't touch your face. It's interesting, when I first started wearing a face shield as I was seeing patients, there were a couple of times where my face was itching and I went to touch it and my finger nearly hit the front of the shield. That's why they are so valuable. And they do give you eye protection, which face masks don't give you.

I understand that some N95 masks have exit valves that allow the exhalation to exhaust without filtering. I see news reports that some places have picked up on this and have asked for the vents to taped off. Does that make sense?

It's a little bit complicated, but N95 masks actually protect you from other people and vice versa. The problem will be, let's say you're infected and you're wearing an N95. If the N95 has an exhaust valve on it, you then can still infect other people. You would be protected from others because these are one way valves, but you might infect another person. Now that can be remedied by just wearing a face mask over the N95 mask to reduce the amount of particles that may be coming out of it. But the person who brought this question up is really raising a very good point. In healthcare, none of the N95s have these valves. But ones that are made for industrial uses or the ones that you might find for example in a hardware store, they often do have these valves and you have to remember to cover it to protect other people.

I read about a company that developed a mask with a layer of a salt mixture that not only blocks the virus but also kills it. I have not heard much about this mask from the scientific folks. Do you know anything about it? 

I do not know about that one. There are various things that people are trying, there are some cloth masks that use a fabric that's impregnated with silver because silver has some properties that we know at least kill bacteria, I don't know that we know as well for viruses. And the medical masks that we wear in the hospital, these paper fiber masks, they have an electrostatic charge that tends to attract and hold on to particles. And that's really one of their major mechanisms for how they work.

In the future when we travel, especially through airports and are wearing face masks for a long time, what type of valved masks should we look for for virus protection? We see PM2.5 types and others with filters, but do these protect you from viruses during travel?

As far as masks go, they primarily serve to protect other people from you. The fancy word we use is "source control". So if you have the virus, we're trying to keep it from getting to other people. There are people who are doing things like putting filters in the masks. I suspect those do provide you some protection but I would say they're not foolproof. One of the problems even with medical grade masks is they don't seal to the face. So there still is space between the skin of your face and the mask itself where you can breathe around them and if you were to cough the particles could come out of the sides of the mask. So even though people are trying to do things to make the masks more protective, like putting filters in them, I still think that these are not foolproof. You still have risks of becoming infected when you're wearing them.

My questions have to do with masks while riding public transit. If there are 3-5 people on a BART car with forced air circulation not wearing masks as required on a 10 minute ride, what is the risk to other masked passengers of contracting coronavirus? This assumes adequate social distancing. How much more risk is there as ride time increases?

Lots to unpack in that question. The longer that you're exposed, the more risk that you have. So typically very short exposures are probably not going to result in an infection, but the longer that you're exposed to a person that is infected, the greater your risk is.

Distance is also very important, the further away that you can be the better. Again that goes back to the person who's unmasked who may be coughing and producing droplets. Most of those droplets are going to fall within six feet, so if you can get more than six feet from a person I think that's very very important.

Are face shields a better option for men with beards?

The issue that this questioner may be getting at is that the N95 respirators that are generally used in hospitals when we take care of patients with tuberculosis for example, we fit them to the person. So we do a fit test to make sure that that mask can be fit to that person's facial structure. That is why there are multiple models of those masks, because not every mask fits every person's face. However, for men who have beards you will never fit a mask. You can't get enough of a seal with an N95 if you're wearing a beard.

Now with face masks you're not getting a seal anyway. You probably are getting less of a seal if you have a beard, but you can't get a face mask to seal to your face even if you don't have a beard.

The trouble restaurants and restaurant patrons will face is that diners can't wear a mask. A face shield would direct a diner's breath downwards. Would that make enough of a difference to help address this problem in that environment?

One of the problems with any kind of face covering, whether it's a face shield or a face mask is you can't eat with them on. You have to take them off to eat because your mouth is covered. So you certainly can wear your face shield into the restaurant and leave it on until your food arrives, and then take it off. We tell our healthcare workers, your face shield stays on until you have to take it off. And that would be to eat, or we allow people to take it off if they're in a room by themselves. Other than that, they should have their face shields on.

Can wearing medical goggles prevent the virus from getting in your eye?

Yes, and that's important. If you're going to wear a face mask, one of the downsides is your eyes remain unprotected. So you can combine goggles with a face mask. The face shield takes care of that, your eyes will be protected.

What is a good recommendation for the duration of use on disposable masks before they should be tossed?

That's a great question and we don't know the answer to that. What we do know is they become less effective as they get wet, and just breathing in them for long periods of time makes them wet. They start to get clogged, they can become hard to breathe through - they were never designed to be used for long periods of time. So they tear, and I would say if the mask is damaged it should be thrown away. If it becomes hard to breathe through, you need to throw it away. And I would say you probably for the most part are not going to get more than a couple days wear out of a medical mask.

Since your team started doing this work on the face shields, have you heard much from public officials seeing this as a good option for lots of people, not just people in hospitals?

We are starting to get more feedback from people who are interested in moving in this direction. It's taking us a little time to get traction; we did have a paper published in JAMA that got a fair amount of publicity and we are starting to see people talk to us about that.