Steven Shein, MD, chief of pediatric critical care and medicine at Rainbow Babies and Children’s Hospital, talks about whether wearing a mask hinders a person’s oxygen levels.
Your mask study covers a lot of ground, doesn’t it?
SHEIN: Yeah, we tried to be very comprehensive with it.
Can you describe the conditions under which you tested people with masks?
SHEIN: So, my team and I studied our subjects in two different conditions. We had them sit quietly for 10 minutes and then we also had them walk briskly for 10 minutes too. And just to give you a sense about how much kind of exertion they were putting out, on average, everyone’s heart rate went up by about 30 points or so.
That is significant in what way?
SHEIN: So really what that shows is that their body was stressed out by the walking. You know, whenever your body is stressed out for whatever reason, your heart rate almost always goes up. And the fact that their heart rate went up by 30 points shows that this was a substantial amount of exertion.
Therefore, I guess, you’re taking in more oxygen?
SHEIN: So certainly, your oxygen utilization goes up when you’re exercising. But what our study was looking at was not how much oxygen you’re using, but whether or not you can get oxygen into your body safely while wearing a mask. Your lungs have two main jobs, to get oxygen in and to get carbon dioxide out. So, what we did is we used a special medical probe that attaches to the forehead and it measures their oxygen level, the subject’s carbon dioxide level, and also measures their heart rate too, since heart rate tends to go up whenever your body is stressed for really whatever reason.
How did you measure the oxygen levels and what did you find in those measurements?
SHEIN: Yeah, so we used a medical sensor that attaches to the subject’s forehead and it uses both light and heat to measure oxygen levels and carbon dioxide levels inside the blood and also the subject’s heart rate too. And the reason we do that is because your lung has two main purposes, to get oxygen in and to get carbon dioxide out of your body. So, if your lungs aren’t working well, if you’re not getting enough air in and out of your body, your oxygen levels are going to fall or your carbon dioxide levels might rise. And what we found in this study was that when subjects wore a mask, either a cloth mask or a surgical mask, that their oxygen levels stayed normal and the carbon dioxide levels stayed normal and their heart rate stayed normal too, showing that they really weren’t stressed out by anything other than the fact that they were up and walking around pretty quickly.
There’s been some resistance to mask-wearing by some of the people who have breathing problems, like asthma, for instance. What did your study find?
SHEIN: So, my research team and I studied 50 subjects, and these were all adult volunteers, people that work here at University Hospitals and Rainbow Babies and Children’s Hospital. And of the 50 subjects, on average, the people were either in their 30s or 40s, though we had some people that were older as well, and about one third of them had a self-reported medical condition, most commonly asthma. So, this is a generally healthy population, but a generally kind of normal population. You know, this was not people that are just, you know, triathletes or anything like that. And our study found that when we had these subjects sit without a mask and then with a surgical mask and with a cloth mask, that their oxygen levels and carbon dioxide levels stayed the same. And when we repeated the study, when we had them walk briskly first without a mask then with a cloth mask and then with a surgical mask, we again found that wearing a mask did not affect their ability to get oxygen into their body or their ability to get carbon dioxide out of their body.
So, if I read the study correctly, your team tested cloth masks and surgical masks and apparently there was no difference in oxygen levels?
SHEIN: Yeah, there were no differences at all. And we thought it was really important to test both cloth masks and surgical masks. And importantly, we had people bring in their own cloth masks. So, this was not some, like, special thing that it was, like, you know, super thin and, you know, we’re trying to kind of put one over on people. These are literally the cloth masks that these 50 people where during their routine lives. But we also wanted to do it in a controlled fashion too, which is why we used surgical masks that we use here at the hospital. And in both parts of the study, both with the cloth mask and with the surgical mask, we didn’t find any difference. Heart rate stayed the same, oxygen level stayed the same, and carbon dioxide levels all stayed the same.
I know you tested singular masks, but there’s been a CDC recommendation to double mask. Would you expect that wearing two masks might change the oxygen levels and why or why not?
SHEIN: I can’t answer with as much scientific accuracy as I can with a single mask because we didn’t study two masks at the same time during it. But I can tell you that when we were kind of developing the study protocol and sort of playing around with the sensor, I personally wore three masks at the same time a cloth mask, a surgical mask, and then a KN95, which is, like, the super sturdy masks that we use when we’re taking care of patients we know we have COVID. And when I wore all three at the same time, my levels didn’t change at all. So that’s not scientifically robust enough to say it with as much certainty as I can about oxygen levels and carbon dioxide levels staying OK with one mask, but I would be very surprised if wearing a second mask would have a significant impact on most people.
As the vaccine rollout continues, folks may be COVID-weary or feel they are maybe nearing the end of mandatory mask wearing, so they’re letting their guard down perhaps. So why is this information relevant now?
SHEIN: I totally get the whole idea of COVID fatigue. I know I feel it. I’m sure pretty much everyone feels it at least to some degree. But I think it’s really important to consider where we are now and, unfortunately, how far we still have to go until enough people have the vaccine that we get what’s called herd immunity. So, in the first week of March, about 12,000 deaths from COVID were reported in the United States. And to put that into context, that’s four times the number of people that died on 9/11. And I’m not trying to be overly dramatic or anything like that, but I think it’s important to realize how dire the situation still is and how many people are still being affected by COVID even in kind of recent weeks. And then in terms of how far we have to go, the most recent estimates are that we’re not going to reach herd immunity until the end of the summer or early fall. And obviously, I hope it’s faster than that. I’m tired of all this. I can’t wait till we don’t have to wear masks anymore. I can’t wait to be able to take my kids to a baseball game and, you know, get back to living normal life. But the reality is we’re not there yet and masks are going to be a part of our life for a bit longer now. And what I hope from this study is that, if there are people out there that are hesitant to wear a mask simply because they don’t think they’re going to get oxygen into their body or carbon dioxide out, I hope that our study shows them that for most adults that is not a problem and it gives them a little bit more peace of mind as they’re wearing a mask so that we can all do our fair share to try to keep this pandemic at bay as best we can until we get the vaccines out there enough that we can all go back to normal.
I know you mentioned that these are mostly healthy people. What did you want to add to that?
SHEIN: Yeah, so I think one important caveat to our study is that these were 50 adults who are healthy enough to work and healthy enough to walk 10 minutes briskly without significant trouble. So certainly, there are people out there who have very severe lung diseases or cardiac diseases or potentially other problems as well where there is a chance that wearing a mask could have a small impact with their ability to get air in and out of their body. If you think you’re one of those people, what I would tell you is that you should go either see your doctor or at least talk to your doctor. It’s very easy to measure oxygen levels. The carbon dioxide sensor is a little bit more of a kind of specialty monitor. But if you at home have any concerns about your own ability, you should talk to your physician. They might be able to even test your oxygen levels with and without a mask. But what our study shows is that, for most adults that the chances of having a significant trouble with oxygen getting in or carbon dioxide getting out is essentially zero.
Interview conducted by Ivanhoe Broadcast News.
END OF INTERVIEW
This information is intended for additional research purposes only. It is not to be used as a prescription or advice from Ivanhoe Broadcast News, Inc. or any medical professional interviewed. Ivanhoe Broadcast News, Inc. assumes no responsibility for the depth or accuracy of physician statements. Procedures or medicines apply to different people and medical factors; always consult your physician on medical matters.
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