How Safe Is Your Mask? A Quick Science Check
Since the COVID‑19 outbreak, we’ve been mixing and matching masks—store‑bought, DIY paper towels, polyester cloth, you name it. But how many of them actually keep the tiny 20‑100 nm virus particles out of your breath?
Enter Dr. Tomoaki Okuda
Professor Okuda of Keio University set up a simple test using a Scanning Mobility Particle Sizer (SMPS). Think of it like a miniature vacuum that pulls air through a hose, counting the microscopic particles inside.
He then wrapped each mask around the hose’s opening and measured how many particles slipped through. The results? A clear ranking that shows which masks are truly clutch.
1. Surgical Mask
A four‑layer, liquid‑proof button on the nose, the all‑professional surgical mask was the top performer. It let in only about 2 % of the tiny particles we tested for.
2. Homemade Cloth Mask
Made of regular cotton or muslin, this mask was less efficient than the surgical one but still held its own, allowing around 10 % of the particles through. Worth it if you’re looking for a decent DIY option.
3. Paper Towel Mask
Surprisingly, the paper towel mask was the weakest link. It let in roughly 25 % of the particles. So, next time you’re tempted to roll a paper towel into a mask, consider the other options first.
Takeaway
- Surgical masks are the gold standard—they’re tough on particles and reliable.
- Cloth masks work best if you’re going DIY, especially with multiple layers.
- Paper towels? Not so great. Keep them for faceshields, not masks.
Bottom line: don’t just mask up—mask smart. Your lungs (and the world) will thank you.
Surgical mask
With a store-bought surgical mask, the SMPS measured around 1,800 particles per cubic centimetre of air passing through. The results show that the mask has a collection efficiency of around 70 per cent, a high blockage rate for the estimated virus particle size.
Paper towel mask
Using three paper towels folded in half, Okuda tested a six-layer paper towel “mask”. The SMPS measured around 1,000 particles per cubic centimetre of air passing through. With a collection efficiency of around 80 per cent, the paper towel mask appeared to be more effective in blocking out the estimated virus particle size compared to the surgical mask.
Cloth mask
A makeshift mask made out of a handkerchief folded thrice emulated the results of the surgical mask. The SMPS measured around 1,800 particles per cubic centimetre of air passing through, with a collection efficiency of around 70 per cent for the estimated virus particle size.
No mask
What Dr. Okuda’s Experiment Tells Us About Sneezing in a Crowd
When Dr. Okuda turned off the mask on the hose he was testing, the SMPS (particle counter) went wild, reading about 6,000 tiny specks per cubic centimetre—all of them between 10 and 150 nanometers. That’s basically the size of a virus.
Why This Matters
- Close proximity counts: If you’re standing next to someone who’s got the flu or coronavirus, you’re potentially inhaling a ton of virus particles.
- The sneezed cloud: Even in an air‑conditioned room, the numbers don’t drop dramatically—just like the jokes about sneezes never hushed up.
- Guard your breath: Masks work because they chop down that particle cloud before it reaches your lungs.
Bottom Line
We’re surrounded by invisible waves of viruses whenever someone nearby is infected. Don’t underestimate the power of a well‑placed mask—think of it as a superhero cape that keeps the bad guys at bay.
Conclusion
Looking at the results, wearing a mask does seem to lower the chances of getting infected. Surprisingly, the mask fashioned from a handkerchief has the same effectiveness as a surgical mask, but even more so, who knew paper towels were the most effective?
However, regardless of which mask is the most effective, what’s most important is to have good hygiene care and to wear masks properly. Here are also some tips on how to modify or wash your government-issued mask so that it can last longer.
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