Researchers from the National University of Singapore analyzed the scientific literature on the effectiveness of anti-covid-19 masks. The results show that if at least 70% of the population uses effective masks (such as surgical masks) in public, the pandemic can be prevented.
Various uses Mask type, Whether it’s hygiene, surgery, hygiene or impromptu household fabrics, all in Transmission reduction SARS-CoV-2 and its severity.
This is one of the conclusions drawn by a group of researchers from the United States. National University of Singapore After reviewing the research published so far on how masks filter or block the coronavirus.his Review Published in a magazine Fluid physics.
He said: “The results show that if at least 70% of the population regularly use this type of mask in public, then effective masks (such as surgical masks) should be used to eradicate the pandemic.” Sanjay kumarThe author of the study, referring to Analog mathematical model in the city new York.
He said: “Even inefficient cloth masks, if worn continuously, may delay transmission.” Another in many studies They have already checked.
Although the public knows which method is most effective, especially when filtering the smallest droplets, factors such as price, comfort, or design can influence the decision to use. “In order to effectively capture droplets, the mask filter must contain Pores; However, small pores will prevent air circulation and cause uncomfortable conditions for users. “The study explained.
In any case, the key aspects of the mask’s function are related to people talking, singing, sneezing, coughing, or even just the size of the droplets ejected from the nose and mouth when breathing. The largest is the most common, with a size between 5 and 10 microns. However, these droplets are still small compared to human hair with a diameter of about 70 microns.
Even the smallest droplets (droplets smaller than 5 microns) (although experts cannot be sure where to set the limit) can be the most dangerous. These will atomize and stay suspended in the air for a long time. Among many types of masks, only N95 can filter them.
Elements to be improved
Researchers believe that one of the factors that has the greatest impact on consumers when choosing one or another mask is Thermal comfort, “An important aspect, because it may affect the compliance of using the product in summer or tropical countries.” Due to prolonged use in hot and humid environments, users report skin rashes, increased heat stress, sweating or discomfort.
The author also found that masks made of mixed polymer materials can filter particles efficiently while cooling the face. The fibers used in these special masks are transparent to infrared radiation, allowing heat to escape below.
Another parameter considered is Flow resistance The breathability of the mask means you can breathe easily. The comment explained: “Long-term use of masks can cause some side effects to human health, such as drowsiness or abnormal heart rate.”
Visualization of breathing air with and without mask when considering two ventilation rates (7.5 and 15 liters/min).
Also mentioned that there are some environmental issue Associated with disposable masks. Some of them are made of plastics, which may not be biodegradable, putting a heavy burden on the environment.
In order to verify each mask, science has tried to determine Filter efficiency and leakage rate of the mask. There are more and more numerical methods based on fluid dynamics to evaluate this aspect.
However, after reviewing the published documents, the researchers believe that there is still much room for improvement in this type of work. According to their findings, the response of human lungs to the resistance of the mask during long-term use has not been fully considered.
“There may be a certain relationship between the respiratory resistance and the flow resistance of the mask, and it should be studied at time intervals when using it.” Li XiaopeiHe is another author and deputy director of the Department of Mechanical Engineering of the National University of Singapore.
“In addition, the use of miniature sensors and human replicas developed for these studies can more accurately quantify the environmental conditions in the compartment space inside the mask,” the researchers said.
Kumar, Sanjay; Li Puxi, “In the context of SARS-CoV-2, the view of the fluid flow behavior of respiratory droplets and aerosols through the mask”. Fluid physics2020 year