Kareem Ahmed, PhD, professor in the mechanical and aerospace engineering department, talks about a new study with masks that could shorten the social distance from six feet to four feet.
Interview conducted by Ivanhoe Broadcast News in 2022.
Tell me a little bit about your research. What is it that you and your colleagues are looking at regarding face masks?
PROF AHMED: The premise of the study is to understand how the propagation of aerosols and droplets transmit the virus from one person to another. The focus is primarily on trying to determine the distance of that propagation with and without face covering. And the research is a human research-based study where it includes participants that were involved in the study itself.
Can you walk me through what you had people do in the study?
PROF AHMED: So, it’s a real human-based study where participants would come and speak a phrase which includes all the alphabets and induce a cough. We then make measurements at different spatial positions as the participant speaks or coughs. We use three advanced diagnostics for the measurements. The three of them provide the same thing in terms of the measurement. So, with that, we could get high fidelity measurement of the aerosols and droplets that do emit from the participants.
What were your findings?
PROF AHMED: The key finding is that we are all following the CDC guidance in terms of a six-foot distance. What we found is that the aerosols and droplets are propagating at a shorter distance, around four to five feet. With a face mask, a typical cloth-based based face mask, it is reduced to about two feet, but with a disposable three-layer surgical blue-like mask, that is reduced to about half a foot.
From the start of the pandemic, we’ve been hearing six feet. So, could the distance be shortened?
PROF AHMED: Yes, absolutely. The key message is that the physical distancing could be significantly reduced than the six-feet distance based on a cough and a speech, which is mostly where the virus is being transmitted. Because otherwise, if you’re sneezing, you’re home sick, right? So, the point is that you could reduce that distance from six feet to a shorter distance with a face mask to about three feet with any kind of face mask.
What surprised you most about this study?
PROF AHMED: So, early in the pandemic, we noticed in the data that without a face mask, the propagation distance was never six feet, it was around four to five feet range. We wanted to confirm that with this specific study, and that’s where we had to involve different participants of different ages, sex, heights, and weights. By doing that, we saw that it’s about four feet and change. But what was surprising is the results from the cloth mask and the surgical mask. We did not expect the cloth mask to underperform the way it underperformed. We speculated it would be shorter than two feet, but it only reduced it by half, compared to no mask at all. And the other surprising aspect is the three-layer surgical mask. We were surprised with the results that it’s less than a foot. So, these are the two surprising results that we were amazed by in this research.
So, the CDC recommending that people stop using cloth masks proves that point, right?
PROF AHMED: That’s correct. Actually, part of the study, we did the 95KN and the N95. The finding from there is that we couldn’t detect it within that half a foot distance at all. We had no data there at all. So, there was nothing coming out of those. The point out of it is that the fidelity of the face mask will impact that distance, and if you’re wearing these three-layered base masks, you could actually be within a comfortable distance to the person in front of you as you’re talking. The other aspect is that you could use the results from the study to gauge how close or far you could be from another person. So, if a person in front of me is wearing a cloth mask, then I would want to keep a three-feet distance from that person. But if the person in front of me is wearing a surgical mask, then, I could stay within a comfortable distance of about a foot range.
Now, we’re two years into the “never-ending pandemic.” What do you think this research will do in this pandemic? What do you think this research will mean for people when it comes to social distancing and trying to get back to their normal lives?
PROF AHMED: This study defines where we could feel comfortable from a person to another in terms of a safe distance. The key thing is any face covering helps, it reduces that six-foot distance by a half. This study provides that and solidifies that information. One of the key things from this study is that most characterization of face masks has been simulated experiments. This is a real human-driven research study where participants primarily did the phrases and the coughs. And the measurements are done from real humans, so it takes away any questions about the validity of the results.
Now, K95 masks are being handed out. Was that part of the study?
PROF AHMED: Yes, it was part of the study. However, because there weren’t any measurements there, we can’t quantify the effectiveness. It’s zero. So, the point is that the 95 variants were highly effective in filtering our aerosols and droplets that would emit from one person to another.
Is there anything else you feel that people should know?
PROF AHMED: Yes. Besides providing a guidance for a shorter distance with a face mask, the study also provides a guidance of how safe I can be from a person in front of me by knowing the type of mask that they are wearing. If you’re wearing a N95, you could feel safer. If the person in front of you is wearing a cloth mask, then you want to keep your distance from that person, about three feet.
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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