Choosing Between a 2-Layer or 3-Layer Mask - Which Is Better?


With the recent and unfortunate surges of new COVID-19 variants, health organizations have begun reissuing guidance on appropriate face masks for everyday use, especially emphasizing filtration efficiency.

Some guidance has once again pointed to the use of masks with three layers, and there is no question that adding more layers to the mask will make it better at blocking particles. But it's not just the number of layers that determine the filtration efficiency of your mask, but also the type of fabric and its construction that determine overall effectiveness.

It's possible to get better filtration (and breathability) with two layers if you choose the right mask. Let me share some test evidence to show how. 

In late 2020 we began working with a major US airline who tested NxTSTOP masks in their lab. Not only was NxTSTOP selected over 50+ other vendors to provide masks to all airline employees (more details of that partnership coming soon!), but we also received filtration data on the top performing masks. 

The study was based on two widely publicized approaches (see below*) to measure the effect of droplet transmission as a result of speaking through different mask types. A lower number indicates better containment of particles. 

The results are below. For reference, the score with no mask was 727.5.

Mask Scoring: Average Number of Droplets Observed After Speech

Once again, we see how bamboo is truly the winner here. The two layer bamboo mask still scores better than the three layer cotton mask, and twice as good as the two layer cotton masks. 

The key takeaway is that a high performance bamboo mask can have better filtration but still maintain better breathability and comfort given fewer layers. When you may be wearing your mask for hours on end, especially traveling, comfort and breathability become enormously important. 

For those who still feel they want even better filtration, there is also the option to choose a three layer bamboo mask with a filter pocket insert, or the bamboo silver ion mask for additional levels of hygienic protection. 

 

*Aerosols and droplets generated during speech have been implicated in the person-to-person transmission of viruses. Two studies, one conducted by the NJIM, Visualizing Speech-Generated Oral Fluid Droplets with Laser Light Scattering and one conducted by Duke University, Low-cost Measurement of Face Mask Efficacy for Filtering Expelled Droplets During Speech, provided methods to measure the effect of droplet transmission as a result of speaking. Results provided for NxTSTOP face masks do not provide express guarantee against particle transmission, and NxTSTOP makes no claims or guarantees as to the test procedure or results.

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