In a recent study, researchers tested household materials that could be used to make DIY masks, but they left out one common material—paper towel (also called “kitchen paper”). Could paper towel be an effective material for making homemade masks in times of crisis and shortages? Smart Air Engineer Paddy tested its effectiveness in the Smart Air test lab in Beijing.
Putting Paper Towel to The Test
Paddy used a Met One particle counter to test how well a single and double layer of paper towel filtered out particles down to 0.3 microns. Paddy ran the Met One for one minute, measuring the total number of particles passing through the paper towel versus the same setup with no filter.
How Big Are Viruses?
Just how small is 0.3 microns compared to viruses? The coronavirus measures approximately 0.1 microns in diameter, so 3 times smaller than measured in our test. However, 0.3 microns is an important size to test, because 0.3 micron particles are the most difficult to capture.
Paper Towel Particle Capture
The results weren’t great. A single layer of kitchen paper captured just 23% particles. Adding an extra layer only increased particle capture to 33%.
For larger 2.5 micron particles, paper towel performed better. The single layer of kitchen paper captured 52% of these larger particles.
Do Kitchen Paper Masks Fit Tight?
One thing this test doesn’t cover is fit effectiveness–how leaky a DIY mask would be. Not surprisingly, masks that fit better will let fewer particles in. That’s one of the reasons why surgical masks score lower on fit tests than N95 masks.
Yet Studies Find Mask Leakage Has Small Effect on Flu Virus Transmission
Although surgical masks (and presumably DIY masks) are more leaky than N95 masks, randomized studies that have tracked infection rates have found that surgical masks are just as effective as N95 masks at preventing the transmission of viruses. Researchers don’t know the exact reason for this. However, some scientists hypothesize that masks help, in part, because they prevent us from touching our face. That helps keeps us from “planting” viruses our mouth, nose, and eyes.
Bottom line: Paper towel captured fewer particles than other DIY mask materials tested by researchers at Cambridge. However, if it is the only material you have, it is better than nothing.
Paddy is the CEO of Smart Air, running operations from Beijing. He’s 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.