Amid the rush for masks with the coronavirus, we’ve found that some people are wearing masks the wrong way round! But does wearing surgical masks the wrong way round affect their ability to capture viruses?

Some online sources claim it doesn’t matter, like this one.

 

Surgical masks are made up of 3 layers, and there is a specific way to wear them: with the colored, rough-textured side out.

 

 

But does the direction you wear it actually affect its ability to capture viruses? Smart Air tested sub-micron particle capture to see whether the orientation of a surgical mask really affects performance.

 

Testing Surgical Mask Efficiency from Both Sides

 

To test the surgical masks, we used the same wind tunnel setup that was used for our homemade mask materials tests. In that setup, a fan on one side of a wind tunnel pushes air through the mask on the other end. There, a Met One GT-521 laser particle counter measures how many particles penetrate the mask.

 

 

We tested the blue side and white side of four surgical masks.

 

 

We measured what percentage of particles 0.3 microns and above they could capture. Although the new coronavirus is 0.12 microns on average, scientists sampled air in hospitals and found that SARS-CoV-2 sometimes travels on aerosols from 0.25-0.50 microns.

 

 

Surgical Mask Blue vs. White Side Results

 

Across four masks, putting the mask in the correct direction improved particle capture by 1.7% on average. On one mask model, the improvement was nearly 3%.

 

Although these numbers are pretty small, wearing the mask the right way will increase its effectiveness at capturing virus-sized particles.

 

 

Remember: Rough Blue Side Out, Soft White Side In

 

This data backs up the claim that the colored side of surgical masks (typically blue or green) should face out.  The softer white layer should face in.

 

 

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