A chart shows the best and worst face mask types based on the latest research

A simple trick can reveal whether your face mask provides adequate protection: Try blowing it out while wearing a candle. A good mask should prevent you from extinguishing the flame.

This rule is not silly, but it will help weed out a mask that is not very protective.

Since the Centers for Disease Control and Prevention (CDC) began recommending cloth masks to the general public in April, researchers have been evaluating the best materials for filtering coronavirus.

An ideal mask blocks both large respiratory droplets from coughing or sneezing – the primary method by which people transmit the virus to others – with small gaseous particles called aerosols, which are produced when people talk or breathe.

It should be sealed around the nose and mouth, as any gaps, holes or pores can leak out and potentially infect another person.

Assuming the mask is worn properly, some materials consistently study better than others. Based on the latest research, here is a ranking of the best and worst facial ings:

5f513b59e6ff30001d4e6ef2(Yuking Liu / Insider)

‘Hybrid’ masks are one of the safest options at home

As a general rule, mask fabrics should be woven as tightly as possible. That is why fabrics with high thread counts are better for filtering particles.

It is even better to have more than one level. The World Health Organization (WHO) recommends that fabric masks have three layers: an inner layer that absorbs, a middle layer that filters, and an outer layer made of nonabsorbent 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 get in or out. They also contain tangled fibers to filter aerated pathogens – the name refers to their at least 95 percent efficiency in filtering aerosols.

A recent Duke study showed that wearers spread less than 0.1 percent of the drops through the N95 mask when speaking.

That is why they are usually reserved for healthcare workers.

Disposable surgical masks are also made of non-woven fabric. A 2013 study found that surgical masks were almost three times more effective in blocking influenza aerosols than homemade face masks (true, at least, when air flow was slower than coughing but light was faster than human breathing during work).

Still, there are homemade options that come close to the level of protection of N95 or surgical masks.

An April study from the University of Chicago found that “hybrid” masks – two layers of 600-thread-count cotton combined with other materials such as silk, chiffon or flannel – filter at least one percent percent of small particles (less than 300 nanometers) and at least Less than 96 percent larger particles (larger than 300 nanometers). Two layers of 600-thread-count cotton provide the same level of protection against large particles, but they were not as effective in filtering aerosols.

That study, however, conducted the measurement at a lower air flow rate, so that the mask provides less protection against coughing or sneezing. Still, it is better to face multiple layers of high thread-count cotton with ingots made from dishcloth or cotton T-shirt.

Fabrics such as silk or cotton have more variable performance

A June study published in the journal Hospital F Spital Infections found that masks made from vacuum-cleaner bags were among the most effective alternatives to surgical masks, followed by masks made from tea towels, pillows, silk and 100 percent cotton T-shirts, respectively.

During research from the University of Illinois, it was found that the brand new dishcloth was a little more effective than using a 100 percent cotton T-shirt on filtering drops when someone 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-velocity drops, probably because silk has electrostatic properties that can help trap small viral particles. Is.

The University of Chicago study came to a different conclusion, however: The researchers found that a single layer of natural silk filters only 54 percent in small particles and 56 percent in large particles. In contrast, four layers of natural silk filter low air percent small particles and 88 percent large particles at low air flow rates.

Bandana and scarves do not provide great protection

Bandana and scarf have performed poorly in multiple studies.

A study by the Journal Hospital Fah Hospital Spital Infection found that sharing a scarf with an infected person for 30 seconds reduced a person’s risk of infection by only 44 percent. After 20 minutes of exposure, the scarf alone reduced the risk of infection by 24 percent.

Similarly, Duke researchers found that Bandana reduced the rate of droplet transmission by a factor of two, which made them less protective than most other materials.

For the most part, though, any mask is better than no mask at all, with one notable exception: the CDC warns people not to wear masks with built-in valves or vents.

One-way valve masks can expel infectious particles into the atmosphere, which helps fuel the transmission.

Mask study should be taken with salt granules

Although research is unified around the idea that some types of masks offer the best protection, it is not always easy to simulate how the mask will work in real life.

This is because only a few tests directly mimic the size of the novel coronavirus particles, while others evaluate performance based on viruses such as influenza. Researchers are still unsure of the degree to which viruses are transmitted by aerosols, as those tiny particles are extremely difficult to trap and study without killing the virus.

Some scientists also have differing views on what constitutes an aerosol – the generally accepted cutoff is less than 5 microns (approximately the size of a dust particle) – and many experts believe that the descriptions are completely arbitrary.

Different studies also test the mask in different circumstances: some mimic the heavy air flow produced when a person coughs, mimic the air flow when a person normally speaks or breathes.

And of course, masks perform differently depending on how they are worn. That’s why it’s better to stick with more security than less.

This article was originally published by Business Insider.

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