The Scientific Efficiency of Wearing the Right Mask

by Lucy Sokol ‘21

Masks. Within the past few months, they have become one of the most essential items you need when leaving the house. While masks help prevent you from contracting and/or spreading the Covid-19 virus, it is beneficial to know the science and analytics behind that piece of material you cover your nose and mouth with. 

According to the CDC COVID Data Tracker as of September 8, the U.S has a total approximately 6.2 million cases of Covid-19, with 638,000 cases in Texas. The Texas Tribute, a state-wide news website, explains that while Gov. Greg Abbott ordered all residents to wear a face covering in public on July 3, he let Texas counties with fewer than 20 cases opt out of the mask order. A week later, 78 counties took that option, and by that Thursday more than 9.6 thousand people were hospitalized with the Covid-19. With many counties not enforcing masks, Texas has the third-highest number of Covid-19 cases.  

Like the flu, people are most likely to transmit Covid-19 when respiratory droplets get onto another person. According to studies from the University of San Francisco, an experiment involving a high speed camera found hundreds of droplets ranging from 20 to 500 micrometers when saying a short and simple sentence. When testing the same experiment on an individual wearing a mask, nearly all the droplets were blocked. Another independent study titled, “Visualizing the Effectiveness of Face Masks in Obstructing Respiratory Jets,” showed that an uncovered cough has its droplets travel an average distance of eight feet, while wearing various masks reduced that distance by more than half, with the best masks reducing it all the way to 2.5 inches. 

So what is considered the best mask? In the article, “The Science Behind Masks,” an ACS Nano chart defines the N95 mask as the most protective mask based on a display of flow efficiency for each type of mask. When worn correctly, meaning no gap between the face and the mask, the N95 filter efficiency is 99.9 percent when put on a greater than 300 nanometer scale. While N95 masks are ranked as the most effective, surgical masks come in at second place with a filter efficiency of 99.6 percent. Not to mention, the blue disposable surgical masks are more accessible to the general public as you can find them at grocery stores or convenience stores. 

Now let’s talk about the masks to avoid. CDC revised face mask guidelines and explained that people should avoid masks with valves or vents. CDC explains that the purpose of a mask is to keep respiratory droplets from going past the mask and reaching other people. Masks with one-way valves allow for respiratory droplets to leave the mask and potentially reach others. A Youtube video published by Duke Health shows the droplet variation of fourteen different times of masks. The neck fleece was ranked one of the worst, as the fleece broke down the large particle to smaller particles, actually producing more of them. The particles tend to hang around longer in the air, making it easier for other people to come into contact with. 

While a pandemic is new to everyone, it is important to consider and acknowledge the scientific evidence of wearing a mask as it could save yourself or someone else from contracting Covid-19. To flatten the curve, everyone must participate. Do your part.