What is the 'candle test' to find out how effective non-medical masks are in combating infectious diseases?

'Wearing a mask' is said to be effective as a countermeasure against the new coronavirus infection (COVID-19), but not all high-performance medical masks are available. For those who are wondering how effective non-medical masks and handmade cloth masks on the market are, infected with ``How to check whether the mask can perform its original function'' at the

University of New South Wales Professor Raina Mac Intyre, who studies diseases prevention, explains.

How do I know if my mask actually works? What about the'candle test'?

Studies have also reported that a certain percentage of people can mask the COVID-19 epidemic if they wear masks, and some countries and regions are obliged to wear masks in public places. On the other hand, many people are wondering whether commercially available non-medical masks or handmade cloth masks are a measure against COVID-19.

MacIntyre says that masks that aren't labeled as 'medical' may simply not be approved as medical devices, so they're 'not necessarily useless to prevent infectious diseases,' he said. He explained that the 'structure of the cloth mask' and 'presence or absence of water resistance' are important when considering the effect.

◆Structure of cloth mask
For example, in the case of a cloth mask, the more layers that make up the mask, the better the function as a filter. MacIntyre argues that it is better to wear a mask with one layer of cloth than not to wear a mask, a two-layer mask over a one-layer mask, and a three-layer mask over a two-layer mask. , It is recommended to layer more than 3 layers of cloth if possible. He also said that the material should be as close as possible and dense so that droplets and aerosols cannot pass through the mask.

When making a mask, you also need to consider the order in which the fabrics are stacked. Although pure cotton has a good feel to the skin, it has a high water absorbency, so if pure cotton is used as the outer layer of the mask, there is a risk that someone will absorb the droplets that have been blown by coughing or sneezing. Therefore, MacIntyre advises that the fabric used for the outer layer of the mask should be made of

polyester, which has excellent water resistance.

When using pure cotton, it is better to use it for the innermost layer, and if pure cotton with excellent water absorption is on the inside, it absorbs the moisture contained in the exhaled breath and seems to be comfortable. It is also important that the mask fits well to the face. If there is a gap between the mask and the face, the surrounding air will be sucked in directly, and the meaning of the mask will be diminished. There are various ways to fill the gap between the mask and the face, but experts have shown you how to apply medical tape, fill the gap with moistened tissue, and cover the mask with nylon stockings. I will .

◆ Candle test
As a method of checking the performance of masks, there is a ' candle test ' popularized by American science educator Bill Nai . This is ``to check if you can extinguish the candle's fire with the mask on,'' if the candle extinguishes, the mask can not stop the flow of air sufficiently, the candle's fire If does not disappear, it means the mask is blocking air.

You can see how to actually check the function of the mask with the 'candle test' by watching the following movie.

ABC 6 takes on Bill Nye's mask vs. candle experiment-YouTube

Mr. Nai eagerly talks about the importance of wearing a mask.

Mr. Nai introduced in the movie posted on TikTok is the 'candle test' that checks if the candle can be extinguished while wearing a mask.

American TV station WSYX has decided to do a candle test on a variety of masks, including just bandanas, cloth masks, N95 masks for particulates, and medical masks on the market.

A male reporter standing in front of a lit candle has a bandana on his face.

When I breathed in, the candle light went out. A thin bandana seems to breathe easily, so it can be said that it does not function as a mask.

Next, a cloth mask made at home.

Although the mask blows up with the momentum, the candle does not go out.

You can see that even a cloth mask can sufficiently block the air flow.

Next, we will conduct an experiment with the N95 mask used at the manufacturing/construction site and the medical site for infectious diseases.

After all, the candle does not go out.

This time, a commercially available two-layer cloth mask.

Even with this, the candle's fire did not go out. Even a two-layer cloth mask seems to have some effect on infection control.

The last is a thin medical mask. Medical masks are thinner than cloth masks, and they seem unfriendly in terms of blocking the flow of air, but...

Although the candle fire shook slightly, it successfully cleared the candle test. It can be seen that even though the mask is thin, the mask has been approved as a medical device and has an excellent effect of blocking air.

◆Water resistance test
The virus is carried on droplets that are blown off by coughing or sneezing, so if the droplets attach to the mask, the outer layer is required to repel the droplets. Therefore, when checking the performance of the mask at home, it is also recommended to do a test 'try to drip water drops on the outside of the mask'. MacIntyre said that if the droplets were absorbed by the mask, there was a problem with the water resistance of the mask, and if the droplets were repelled like beads, the water resistance of the mask was not.

in Science,   Video, Posted by log1h_ik