Japanese chemistry professor tested three types of face masks for their efficacy

According to one test, disposable paper masks, fabric masks and paper towels could be effective at filtering out particles from the air

Kaila Imada
Written by
Kaila Imada
Associate Editor, Time Out Tokyo

With the rapid spread of the Covid-19 coronavirus, people have been stocking up on groceries, toilet paper and surgical face masks. The resulting shortage of face masks, in particular, has caused the government to step in, promising to issue two reusable cloth masks to every household starting this week.

If you can’t get your hands on any masks in the stores, there are plenty of DIY alternatives, including masks made of paper towels and handkerchiefs. But you might be wondering just how effective a homemade mask really is. Well, Dr Tomoaki Okuda, a chemistry professor at Keio University, has recently shared an experiment he conducted on three different types of masks to test their efficiency at filtering out particles in the air, including virus.

In the video, Dr Okuda blows air through three types of masks: a regular surgical face mask, a paper towel mask and a cloth handkerchief, and measures the number of particles that pass through each mask. Dr Okuda's experiment had some pretty surprising results:

  • In the test, a regular disposable paper face mask blocked out 60 to 70 percent of particles in the air.
  • A mask made from three paper towels folded into six layers scored higher on Dr Okuda's test, apparently filtering out 80 percent of the particles. Dr Okuda says this suggests paper towels could be especially good at blocking out much smaller particles.
  • A cloth handkerchief folded three times performed about the same as a disposable mask, filtering out 60 to 70 percent of particles.

Overall, the test results show that while no mask can completely filter out all the particles in the air, they are still useful. Those made from fabric or even paper towels might be a handy alternative to the disposable ones that are currently so hard to find.

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