Warning: Used Masks Provide Less Protection


  • A new 3-layer surgical mask has a 65% efficacy to filter particles while a used one only has 25%.
  • Masks slow down airflow allowing aerosols to be inhaled through the nose.
  • Study recommends choosing a more effective mask, using it properly, and avoiding excessive use.

 A used mask provides lesser protection and is more dangerous than not wearing any mask. 

The reason behind this is explained in the Physics of Fluids study by researchers from the University of Massachusetts Lowell and California Baptist University.  A new three-layer surgical mask is 65% efficient in straining particles in the air.  A used one only has 25% capacity of filtering the particles.

Using a new three-layer surgical mask, they observed and detected particles passed through the face covering and how it affected the wearer’s airflow. They also took into account how the tiny droplets stayed in the airway, face, and where they settled in the nose, deep lung or pharynx.

Masks naturally slow down and trap the flow of air thus making the mask wearers breathe in aerosols into the nose where SARS-CoV-2 lie in wait.

This significantly lowers the efficacy of the mask.  A dirty or used mask would even be less effective to sift through the smallest droplets.

Face masks with pleats also affect airflow patterns leading to less efficient sifting capacity.

Through time and especially during this pandemic, we believe that wearing a mask whether new or used would be better than wearing nothing at all.

But Jinxiang Xi, study author from the University of Massachusetts Lowell and California Baptist University says, “Our results show that this belief is only true for particles larger than 5 micrometers, but not for fine particles smaller than 2.5 micrometers.”

The researchers will also be studying how the shape of masks can affect its effectiveness to ward off COVID-19.

As Xi said, “We hope public health authorities strengthen the current preventative measures to curb COVID-19 transmission, like choosing a more effective mask, wearing it properly for the highest protection, and avoid using an excessively used or expired surgical mask.”

Source: New York Post

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