Wearing a used mask can be more dangerous than not wearing it at all when it comes to warding off COVID-19, a new study finds.
A new three-layer surgical mask is 65 percent efficient at filtering out airborne particles, but with use that number drops to 25 percent, according to the study published Tuesday in the Physics of Fluids.
Researchers from the University of Massachusetts Lowell and California Baptist University say masks slow airflow, making people more sensitive to inhaling particles – and a dirty face mask can’t effectively filter the tiniest droplets.
“It’s normal to think that wearing a mask, new or old, is always better than nothing,” said author Jinxiang Xi.
“Our results show that this belief only applies to particles larger than 5 microns, but not fine particles smaller than 2.5 microns.”
To arrive at their findings, researchers used a computer model of a person wearing a pleated three-layer surgical mask to track how the face that covered the airflow affected and how particles passed through it. They also looked at how the tiny droplets settled on the face, in the airways and where they ended up in the nose, pharynx or deep lung.
They found that wearing a mask “slows down airflow significantly”, decreasing the effectiveness of a mask and making a person more prone to inhaling aerosols into the nose – where SARS-CoV-2 likes to lurk.
“In this study, we found that the protective efficacy of a mask for the nasal airways decreases at lower inspiratory flow rates,” said the study.
The pleats of a face mask also significantly affect airflow patterns, and their effectiveness changes with more use, the researchers found. The team plans to investigate how mask shapes affect protection against COVID-19.
“We hope public health authorities will strengthen current preventive measures to curb the transmission of COVID-19, such as choosing a more effective mask, wearing it appropriately for the highest level of protection, and avoiding the use of an overused or overused mask. expired surgical mask, ”said Xi.