Gently spread the face mask COVID-19; Types of masks, length of use.
The use of facial masks has been recommended by health professionals to help slow the spread of COVID-19. This has led to the exploration of the physiological exposure of the use of facial masks and the transmission of disease, as well as the investigation of other issues affecting the materials, designs and working methods of facial masks.
In The physics of fluids, Through AIP Publishing, investigators turned their attention to research on face masks and their use and summarized what we know today about how facial masks are filtered or blocked by viruses. They also summarize design issues that still need to be addressed.
A key aspect of the face mask function involves the size of the drops of fluid that come out of the nose and mouth when a person speaks, sings, sneezes, coughs or simply breathes. Large drops, about 5-10 microns in size, are the most common. However, these droplets are still fairly small. For comparison, the diameter of human hair is about 70 microns.
The proportion of respiratory air fraction at the beginning / end of inspiration and termination, 7.5 liters per minute (Case I) and 15 liters per minute (Case II). The color blue represents the volume occupied by pure fresh air, while the red represents the volume captured by pure respiratory air. The intermediate colors represent a mixture of fresh and breathable air. Credit: Hugh Pueh Lee
Even small droplets, below 5 microns, are probably more dangerous. These can be aerated and remain suspended in the air for a long time. Of the many types of masks used (cloth masks, surgical masks and N95 masks), only N95 can filter aerosol-sized drops.
Demonstrating a face mask worn for many hours, such as by health care or other essential workers, shows how effective it is to wear an overall mask. Thermal comfort is an important issue, especially in hot and humid environments.
Investigators found that face masks made from a hybrid polymer material can filter particles at high efficiency while simultaneously cooling the face. The fibers used in this special mask are transparent to infrared radiation, which can escape the heat from under the mask.
“There may be some relationship between breathing resistance and flow resistance of a face mask that will need to be studied for face mask-wearing intervals,” said author Have Pueh Lee. “Also, the environmental conditions in the space inside the face mask will need to be measured more accurately using miniature sensors and the development of human replicas for such studies.”
Investigators also reviewed epidemiological studies with the aim of finding out whether facial masks effectively reduce fertility. If the breeding number falls below 1, the spread of the epidemic stops. One study used COVID-19 data from New York State.
Author Sanjay Kumar said the results suggest that continued use of efficient face masks such as surgical masks could eradicate the epidemic if at least 70% of residents continue to use such masks in public. “Even less efficient cloth masks can slow the spread if worn constantly.”
Reference: “Reference to the fluid flow behavior of respiratory drops and aerosols through the facemask SARS-CoV-2By Sanjay Kumar and Hugh Pueh Lee, 24 November 2020, The physics of fluids.
DOI: 10.1063 / 5.0029767
