A computer model helps us to understand how particles in the airway are moving and how surgical masks work.
While many know wearing a face mask helps control the spread of COVID-19 in the population, less is known about the effectiveness of the masks in the wearers’ airways.
In the article, researchers from the University of Massachusetts Lowell and California Baptist University found that wearing a three-layer surgical mask can help minimize the particle deposition that occurs during inspiratory airflow.
“”It is common to think that wearing a mask, whether new or old, is often better than doing nothing.” Our findings show that this belief is only true for particles larger than 5 microns, but not for fine particles smaller than 2.5 microns. (The SARS-CoV-2 virus can be no less than one micrometer in diameter – ed.).
The study showed that using a mask with poor filtration efficiency is of lower impact than not using a mask.
They created a computerized face mask model in a physiologically accurate manner using a computerized 3-D model of a human wearing a surgical mask.
They investigated the actions of aerosols as they move through the masks, onto the mouths, and into the lungs, finally settling in the respiratory system.
The model showed that a mask changing the airflow patterns around the face allow air to reach the face through a complete mask surface at a slower velocity.
The slower velocity near the face provides inhaling of aerosols into the nose, resulting in inhalation of more pollutants than can be filtered by a mask.
Researchers checked the filtration performance of 3 separate surgical masks when they were fresh and after extensive usage. So wearing a 65% Filtration mask provides decent protection, but wearing a mask with 25% concentration offers better protection than not wearing one at all.
We hope that health authorities improve existing preventive measures to curb COVID-19 transmission, such as selecting the most appropriate mask, wearing it appropriately to optimize its protective health benefits, and not using an overused or expired surgical mask.
The researchers found that the wrinkles of a surgical face mask strongly influence airflow patterns, and that the form of the mask must also be taken into account in the design of new masks. Xi said they will continue to test the effects of mask shape on human respiratory efficiency.
The study of “Effects of mask-wearing on the inhalability and deposition of airborne SARS-CoV-2 aerosols in human upper airway” was carried out by Xi, Si, and Nagarajan.