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Visualization shows exactly how face masks stop COVID-19 transmission

A dramatic new visualization shows exactly why it's a good idea to wear a face mask to prevent the spread of the new coronavirus. 

Without a mask, droplets produced during coughing can travel up to 12 feet (3.7 meters), the visualization revealed, but with a mask, this distance is reduced to just a few inches in the best cases.

The simulation, which was described today (June 30) in the journal Physics of Fluids, also reveals that some cloth masks work better than others at stopping the spread of potentially infectious droplets.

"The visuals used in our study can help convey to the general public the rationale behind social-distancing guidelines and recommendations for using face masks," study lead author Siddhartha Verma, an assistant professor at Florida Atlantic University's College of Engineering and Computer Science, said in a statement.

Related: 13 coronavirus myths busted by science

To simulate a cough, the researchers connected a mannequin's head to a fog machine (which creates a vapor from water and glycerin), and used a pump to expel the vapor through the mannequin's mouth. They then visualized the vapor droplets using a "laser sheet" created by passing a green laser pointer through a cylindrical rod. In this setup, simulated coughs appear as a glowing green vapor flowing from the mannequin's mouth.

The researchers then placed several types of non-medical masks on the mannequin head to test their effectiveness at blocking these "coughs." These included a homemade mask stitched with two layers of cotton fabric used for quilting (with 70 threads per inch), a single-layer bandana, a loosely folded cotton handkerchief and a non-sterile cone-style mask sold in pharmacies.

They found that, with no mask covering, the simulated coughs traveled up to 12 feet in 50 seconds.

The homemade stitched cotton mask — with its multiple layers and snug fit — reduced the spread of the droplets the most, although there was some leakage at the top of the mask between the nose and the cloth material. When the mannequin wore this mask, droplets traveled only about 2.5 inches (6.35 centimeters) forward from the face. The cone-style mask also worked well, with droplets traveling just about 8 inches (20 cm) from the face.

In a new visualization, researchers simulated a cough, which appears as a glowing green vapor flowing from a mannequin's mouth. The visualizations shows that face masks dramatically reduce the spread of cough droplet particles, from 12 feet without a mask to just a few inches with a mask. Homemade cloth masks (top) and cone-style masks (bottom) worked the best at reducing droplet spread, although there was some leakage at the top of the mask in each case.

In a new visualization, researchers simulated a cough, which appears as a glowing green vapor flowing from a mannequin's mouth. The visualizations shows that face masks dramatically reduce the spread of cough droplet particles, from 12 feet without a mask to just a few inches with a mask. Homemade cloth masks (top) and cone-style masks (bottom) worked the best at reducing droplet spread, although there was some leakage at the top of the mask in each case. (Image credit: Florida Atlantic University, College of Engineering and Computer Science )

However, the single-layer bandana (made from an elastic T-shirt material) and folded handkerchief were less effective. Droplets leaked through the mask material and traveled more than 3.5 feet (1 m) with the bandana and more than a foot (0.3 m) with the handkerchief.

Still, "although the non-medical masks tested in this study experienced varying degrees of flow leakage, they are likely to be effective in stopping larger respiratory droplets" from dispersing, the authors wrote in their paper.

"Promoting widespread awareness of effective preventive measures [for COVID-19] is crucial at this time as we are observing significant spikes in cases of COVID-19 infections in many states, especially Florida," Verma said.

Originally published on Live Science.  

  • mgallagher465
    First, while this was very instructive, it would have helped to include a discussion of particle size blocked by the various masks. However, regardless of WHAT gets through it is also important to know HOW FAR it gets, so very helpful.

    Second, I would like to have seen a visualization of a hand/handkerchief/elbow sneeze as well, as this should be an acceptable option for people that can't wear masks (e.g., asthma).

    Third, all of those visualizations make me concerned about a massive spike in conjunctivitis (pink eye) and other ocular issues as every mask appears to result in blow-back into the cougher's eyes. Yes, pink eye is less serious than COVID, but it's also highly contagious and I don't know what other ocular risks would come from those germs.

    Finally, if I am regularly coughing or sneezing I would probably not be going out regardless. The bigger issue being discussed is the value of a mask in regular activities without coughing or sneezing or exercising or singing, but simply walking near people in a store or restaurant and just breathing.
    Reply
  • CarmenR
    admin said:
    But some cloth masks appear to work better than others at stopping the spread of potentially infectious droplets.

    Visualization shows exactly how face masks stop COVID-19 transmission : Read more
    Please correct the article -- in one place it says: "droplets traveled only about 2.5 inches (1 centimeter) forward from the face. " This measurement equivalent for inches vs cm. is the other way around - 2.5 centimeters equals 1 inch. So 2.5 inches is a lot more centimeters than one - it is 6.25 cm.
    Reply
  • tortadon
    I seem to be confused. To prove your point A fake head was used with power air exhaust expelling through the tube at the mouth. Would the diameter of the tube not change the type of air flow compared to that of A human? Also does the fluid used have the same weight of fluid expelled from A human? This would change the distance of travel. Also the size of the molecules would seem to also play here. What is the air flow rate of A human breathing and the rate when they cough and was that figured in when the test were run. Since the material will become moist from our breathing was the fake fluid heated to that of A humans breath? Was the test ran with moist cloth like it is when we exhale through time after time?
    With todays tech couldn't A real human with the virus wear A mask and breath through the mask while being measured? Also A cough from the virus infected person would give you distance and volume that could also be measured.
    This report makes it sound like something done on youtube not in A Scientific Lab.
    Reply
  • Wanda
    Useful information, so thank you, although I do agree with some of the reservations expressed by others on this thread.
    I think these insights might be extended to strong additional recommendations for social distancing and minimizing face-to-face conversations (even through masks) with anyone not in one's household. We must not be emitting "spit" or vapor into anyone else's space while this plague is with us.
    Reply
  • cecilia fx
    mgallagher465 said:
    First, while this was very instructive, it would have helped to include a discussion of particle size blocked by the various masks. However, regardless of WHAT gets through it is also important to know HOW FAR it gets, so very helpful.

    Second, I would like to have seen a visualization of a hand/handkerchief/elbow sneeze as well, as this should be an acceptable option for people that can't wear masks (e.g., asthma).

    Third, all of those visualizations make me concerned about a massive spike in conjunctivitis (pink eye) and other ocular issues as every mask appears to result in blow-back into the cougher's eyes. Yes, pink eye is less serious than COVID, but it's also highly contagious and I don't know what other ocular risks would come from those germs.

    Finally, if I am regularly coughing or sneezing I would probably not be going out regardless. The bigger issue being discussed is the value of a mask in regular activities without coughing or sneezing or exercising or singing, but simply walking near people in a store or restaurant and just breathing.
    what you are talking about is a different experiment.

    something like this addresses some of your questions. At least you can see why a human looks like expelling droplets

    it doesn't show masks, but it's looking at different elements
    Reply
  • Govtrumbull
    I am most likely one of the most conservative, politically active member of the blog community. So I'd like to approach this subject from a little different angle. There are a whole bunch of people who oppose wearing masks because they say requiring the use of masks violates their Constitutional Rights. As a Conservative Constitutionalist in the spirit of Jefferson, I beg to differ with my conservative friends.

    Nowhere in the Constitution does it cover a situation like we have right now. The Founders could have never foreseen such a virus, or the results from it. The Constitution is a roadmap for the formation of new laws to cover situations which are not mentioned in this document. No one could have looked into a Crystal Ball and received revelation that the COVID-19 would hit the World population as hard as it has. While it isn't the worst epidemic or pandemic in World History, it is still a deadly virus, especially for those with compromised health conditions. Also it is obvious this virus is easily spread from one person to another, as well as from animal-Human contact.

    Requiring masks to be worn in public is not unconstitutional, because it is covered under the General Welfare Clause of our Constitution. Lawmakers have the duty and responsibility to introduce and pass legislation which affect the whole of the population. Wearing of masks has been proven to curb the spread of COVID-19 in the general population, and the wearing of R-95 or more effective mask have been proven to protect medical workers from the virus. So why is there so much opposition from the conservative side of the isle concerning Covid-19?

    Partly it has to do with the principle of freedom of choice. But this principle falls flat because NOT wearing a mask is a danger to everyone they come in contact with. It has been shown non-medical masks, protect others more than they do wearers of the mask. To go into public and be potentially responsible for making other sick is irresponsible

    The other part is, we conservatives have identified huge errors in both domestic and foreign policy, many of which have no Historical, Scientific, or Political facts or president to back the laws being made, or Treaties being entered into. In fact many decisions made by our government blatantly violate the Constitution and principles of the Founding Fathers. Therefore we keep a watchful eye on politicians and Bills introduced in Congress, as well as Treaties being approved by the Senate.

    I am a strict Jeffersonian Conservative Constitutionalist, who relies on facts, to make pragmatic decisions about the issues.

    If you have any regard for the health and safety of others, WEAR A MASK!
    Reply
  • cecilia fx
    Govtrumbull said:
    I am a strict Jeffersonian Conservative Constitutionalist, who relies on facts, to make pragmatic decisions about the issues.

    If you have any regard for the health and safety of others, WEAR A MASK!
    Thank you. It's always nice to see logic and respect for science influencing behavior
    Reply
  • Walt970
    Govtrumbull said:
    I am most likely one of the most conservative, politically active member of the blog community. So I'd like to approach this subject from a little different angle. There are a whole bunch of people who oppose wearing masks because they say requiring the use of masks violates their Constitutional Rights. As a Conservative Constitutionalist in the spirit of Jefferson, I beg to differ with my conservative friends.

    Nowhere in the Constitution does it cover a situation like we have right now. The Founders could have never foreseen such a virus, or the results from it. The Constitution is a roadmap for the formation of new laws to cover situations which are not mentioned in this document. No one could have looked into a Crystal Ball and received revelation that the COVID-19 would hit the World population as hard as it has. While it isn't the worst epidemic or pandemic in World History, it is still a deadly virus, especially for those with compromised health conditions. Also it is obvious this virus is easily spread from one person to another, as well as from animal-Human contact.

    Requiring masks to be worn in public is not unconstitutional, because it is covered under the General Welfare Clause of our Constitution. Lawmakers have the duty and responsibility to introduce and pass legislation which affect the whole of the population. Wearing of masks has been proven to curb the spread of COVID-19 in the general population, and the wearing of R-95 or more effective mask have been proven to protect medical workers from the virus. So why is there so much opposition from the conservative side of the isle concerning Covid-19?

    Partly it has to do with the principle of freedom of choice. But this principle falls flat because NOT wearing a mask is a danger to everyone they come in contact with. It has been shown non-medical masks, protect others more than they do wearers of the mask. To go into public and be potentially responsible for making other sick is irresponsible

    The other part is, we conservatives have identified huge errors in both domestic and foreign policy, many of which have no Historical, Scientific, or Political facts or president to back the laws being made, or Treaties being entered into. In fact many decisions made by our government blatantly violate the Constitution and principles of the Founding Fathers. Therefore we keep a watchful eye on politicians and Bills introduced in Congress, as well as Treaties being approved by the Senate.

    I am a strict Jeffersonian Conservative Constitutionalist, who relies on facts, to make pragmatic decisions about the issues.

    If you have any regard for the health and safety of others, WEAR A MASK!
    That's an absurd statement. Wearing a mask for a healthy person has absolutely nothing to do with regard for the health and safety of others.
    Reply
  • stulio2181
    admin said:
    But some cloth masks appear to work better than others at stopping the spread of potentially infectious droplets.

    Visualization shows exactly how face masks stop COVID-19 transmission : Read more

    What if it's windy?
    Reply
  • Parwan
    Some of the questions and reservations that people in this forum have could be addressed by looking at the actual article. On some sites, unfortunately, I've had no luck providing links. I post a comment with a link, and my post goes away. I'm not sure if that will happen here, haven't checked the rules for this forum closely. I'll provide a link to the article. If all goes well, I'll have more to say later.

    https://aip.scitation.org/doi/10.1063/5.0016018
    Reply