The effectiveness of face masks has been a controversial topic ever since the COVID-19 pandemic began, but research has however provided proof that masks can help reduce the spread of airborne viruses.
What does the science say?
One study found that the airborne pathogens’ traveling distance is reduced by over 50% when wearing face masks when coughing or speaking, compared to not wearing a mask.
The results are important as not only the SARS-CoV-2 virus but also other airborne viral pathogens can be encapsulated and transmitted by the aerosols and liquid droplets formed when coughing and speaking.
Recognizing ways to reduce transmission distance can help keep people safe and help to manage future pandemic response. These responses could include things such as relaxing some guidelines for social distancing when masks are utilized. Social distancing 3 feet with a face mask is preferable to social distancing 6 feet without wearing a face mask.
Diagnostic tools were utilized to understand how fluids move through the air. The distance that aerosols and droplets travel when coughing and speaking in all directions was measured when wearing various types of masks and without wearing masks.
The study included 14 participants between the ages of 21 and 31. Each participant simulated a cough and recited a 5-minute phrase without wearing any mask, wearing a cloth mask, and wearing a disposable 3-layered surgical mask.
Planar particle imaging was utilized for measuring the particle velocity. An aerodynamic particle sizer was utilized for establishing the behavior of airborne particles. And a phase doppler interferometer was utilized for measuring the droplet size, and also the velocity and volume flux in spray plume locations.
The airborne particle’s direction, behavior, and characteristics were measured as they traveled outward from the mouths of the participants. It was revealed that emissions in all directions were reduced to about 2 feet when wearing a cloth mask compared to the 4 feet of emissions produced while speaking or coughing without any mask on.
The reduction when making use of a surgical mask was even greater, the distance emissions from speaking and coughing traveled were reduced to about half a foot.
Another study has also found that surgical masks effectively reduce the outbound airborne particles from coughing or talking, even after the leakage surrounding the mask edges was taken into account.
The study concluded that masks as well as other face coverings are effective in reducing the airborne particle flow produced from coughing, breathing, talking, or sneezing and help protect others from viruses transported by those particles.
N95 respirator masks have a tight seal on the face, but surgical and cloth face masks have small spaces around the edges, which could be reduced when properly worn.
A device that measures airborne particles as small as half a micron was used for measuring the particles flowing from the spaces around the edges of masks.
The study participants were placed in front of the device while coughing or reading aloud, with and without wearing a mask, either directly facing the particle counter funnel, sideways, or with a lowered or elevated head for counting particles passing directly via the mask or leaking around the edges.
The particles passing directly through the mask were reduced by 93% on average when wearing a mask, by 91% from the mask’s bottom, by 85% from the mask’s side, and by 47% from the mask’s top.
Simulations were utilized for modeling the overall particle reduction from wearing a mask, considering edge leakage. The overall efficacy of masks was determined to be about 90% for coughing and 70% for talking.
Even though the overall mask efficacy at minimizing expiratory particle emissions is restricted by air escape, they nevertheless provide a reduction of significance. The results confirm that wearing a mask provides a meaningful reduction in the probability of disease transmission by way of expiratory particles, especially with both infected and susceptible individuals wearing masks. A high-velocity plume flow of air from the talker or cougher is also redirected away from any person in front of them.
Photo by Masao Mask on Unsplash
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