The rule is not foolproof, but it should help remove masks that are not very protective.
Ever since the Centers for Disease Control and Prevention (CDC) began recommending cloth masks to the general public in April, researchers have evaluated the best material for filtering coronaviruses.
An ideal mask blocks both large respiratory droplets from coughing or sneezing – the primary method by which people pass the virus on to others – along with small air particles called aerosols, which are produced when people talk or Exhale.
It should be sealed around the nose and mouth, as any gaps, holes, or vents can allow droplets to leak and potentially infect another person.
Assuming the mask is worn properly, some materials perform better than others in continuous reading. Based on the latest research, here is a ranking of the best and worst face coverings:
‘Hybrid’ masks are among the safest home options
As a general rule, mask clothing should be woven as tightly as possible. This is why fabrics with high thread count are better at filtering particles.
It is also best to have more than one layer. The World Health Organization (WHO) recommends that cloth masks have three layers: an inner layer that absorbs, a middle layer that filters, and an outer layer that is made from non-material materials such as polyester .
N95 masks are the most protective because they seal tightly around the nose and mouth so that very few viral particles leak in or out. They also contain intricate fibers for filtering airborne pathogens – the name refers to their minimum 95 percent efficiency in filtering aerosols.
A recent study by Duke showed that less than 0.1 percent of the drops were transmitted through an N95 mask while the wearer was speaking.
This is why they are generally reserved for health workers.
Disposable surgical masks are also made of non-woven fabric. A 2013 study found that the surgical mask was nearly three times more effective at blocking influenza aerosols than a homemade face mask (this was true, at least, when air flow was slower than a cough but light work. Was faster than a human breathing).
Nevertheless, there are homemade alternatives that come close to the level of protection of an N95 or surgical mask.
An April study at the University of Chicago has determined that “hybrid” masks – combining two layers of 600-thread-count cotton with another material such as silk, chiffon, or flannel – are at least 94 percent smaller particles (300 Less than nanometers) and at least 96 percent larger particles (larger than 300 nanometers). Two layers of 600-thread-count cotton provide the same level of protection against larger particles, but they were not as effective in filtering the aerosol.
However, this study performed measurements at low air-flow rates, so masks may provide less protection against cough or sneezing. Nevertheless, many layers of high-thread-count cotton are preferable to withstand coverings made of a dishcloth or cotton T-shirt.
Fabrics such as silk or cotton have more variable performance
A June study published in the Journal of Hospital Infections found that masks made from vacuum-cleaner bags were among the most effective alternatives to surgical masks, followed by tea towels, pillows, silk and 100 percent cotton T-shirts, respectively. Masks included. .
Meanwhile, research at the University of Illinois found that a brand-new dishcloth was slightly more effective than a 100 percent cotton T-shirt used in filtering drops when a person coughs, sneezes, or talks. That study (which is still awaiting peer review) also found that a used shirt made of 100 percent silk was more effective at filtering high-speed droplets, likely because silk has electrostatic properties that are smaller. Can help trap viral particles.
The University of Chicago study drew a different conclusion, however: Those researchers found that a single layer of natural silk filters just 54 percent of small particles and 56 percent of large particles. In contrast, four layers of natural silk filtered 86 percent smaller particles and 88 percent larger particles at lower air-flow rates.
Bandanas and scarves do not provide great protection
Bandan and scarf have performed poorly in many studies.
The Journal of Hospital Infections study found that a scarf reduced a person’s risk of infection by 44 percent after sharing a room with an infected person for only 30 seconds. After 20 minutes of exposure, the scarf reduced the risk of infection by only 24 percent.
Similarly, Duke researchers found that the closures reduced the rate of droplet transmission due to two factors, which makes them less protective than other materials.
For the most part, however, any mask is better than no mask, with one notable exception: CDCs warn people not to wear masks with built-in valves or vents.
Masks with one-way valves can flush out infectious particles in the atmosphere, which helps in the transmission of fuel.
Masks with salt granules should be studied
Although research is around the idea that certain types of masks provide the best protection, it is not easy to simulate exactly how the mask would perform in real life.
This is because only a few trials directly mimic the shape of novel coronavirus particles, while others evaluate performance based on influenza-like viruses. Researchers are still not sure to what extent the virus spreads through aerosols, because those tiny particles are extremely difficult to trap and study without killing the virus.
Some scientists also have different views about what constitutes an aerosol – the generally accepted cutoff is less than 5 microns (approximately the size of a dust particle) – and many experts believe Delimitation is completely arbitrary.
Different studies also test masks under different conditions: some mimic the heavy airflow that a person produces when coughing, while others mimic the flow of air when a person is talking or breathing normally. Takes.
And of course, the masks perform differently in how they are worn. This is why it is better to live with less protection.
This article was originally published by Business Insider.
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