With the outbreak of the 2019 novel coronavirus, interest has surged in Japanese Pitta masks. Smart Air has received a flood of questions about how well they filter the coronavirus and other viruses.
The Japanese Pitta masks are sleek and incredibly popular, but there’s little information available on how well they filter out tiny virus-sized particles.
How Big Are Coronavirus Particles?
Scientists have taken electron microscope images to measure the size of the coronavirus SARS-CoV-2. They found that the “virions” (or particles) are approximately 125 nm (0.125 microns) in diameter. The smallest particles are 0.06 microns, and the largest are 0.14 microns.
That makes the coronavirus particles smaller than PM2.5 particles, but bigger than some dust particles and gases. However, sometimes the coronavirus hitches a ride on water droplets, which will make the size bigger.
How Well Can Japanese Pitta Masks Capture Virus-sized Particles
Coronavirus & Mask Livestream
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To test how well the Pitta masks can capture tiny particles, Smart Air engineer Kang Wei purchased a pack of Pitta masks and tested them against 3M N95 masks.
To measure particles, we used a Met One 531, which measures particles as small as 0.3 microns. That’s about 3 times bigger than the coronavirus. Research shows that 0.3-micron particles are the hardest to capture. So if a mask does a good job at capturing particles 0.3 microns in diameter, then we can be confident it can also capture smaller, 0.1 micron particles.
Pitta Mask Effectiveness
We compared the Japanese Pitta mask with two 3M N95 masks. The results weren’t pretty.
The Pitta mask captured an astounding 0% of 0.3-micron particles and only 64% of larger 2.5-micron particles. Maybe the result is a fluke? Separate tests from AQ Blue found similar results.
This result strongly suggests that the Pitta mask does a very poor job of capturing 0.1 micron particles, like the coronavirus particles. Meanwhile, the 3M masks captured over 90% of 0.3 micron particles.
In fact, data shows even a surgical mask would provide more protection from the coronavirus than the Pitta mask. Tests from researchers at the University of Massachussetts found that a surgical mask they bought on the streets of Nepal captured over 60% of 0.1 micron particles. A 3M N95 mask captured over 80%.
In short, this data shows the Pitta mask is not effective at capturing small particles. That means it won’t do a good job filtering things like PM2.5, viruses, bacteria, or fine particles.
Does Pitta Claim It Filters Viruses?
In defense of Pitta, their official store never claims that it is effective against PM2.5 or smaller particles for that matter.
The Pitta masks claim to be 99% effective at filtering out pollen and dust particles, which range from 5-100 microns in size. The Pitta mask might be great at capturing pollen, but for viruses such as the coronavirus and flu, the Pitta mask doesn’t cut it.
Paddy is the CEO of Smart Air, running operations from Beijing. He has a Masters in aeronautical engineering from Bristol University, UK having specialised in aerodynamics. An advocate for open data, free information and transparent business, he spends his spare time promoting honest business and social enterprise.