The recurring message from public health experts has been consistent: Masks are the most simple and effective way we can reduce the spread of COVID-19 and save lives.

While doctors, nurses, and support staff working in hospitals and other clinical settings require the protection of N95 masks and other PPE, the guidance commonly offered to the public is that any facial covering reduces the risk of spread. However, new research from Duke University has called into question the efficacy of some common facial coverings.

In a recently published study, the researchers analyzed more than a dozen different facial coverings ranging from hospital-grade N95 respirators to bandanas. The team designed a simple yet effective evaluation tool, using a laser and camera to track and measure the particles released from a person’s mouth when they are speaking. The researchers then asked participants to speak the same phrase into the device ten times with each of the different facial coverings.

Of the 14 masks and other coverings tested, the study found that fitted N95 masks allowed no released droplets at all. Some easily accessible cotton cloth masks were about as effective as standard surgical masks.

The researchers found that popular alternatives such as neck gaiters made of thin, stretchy material may be worse than not wearing a mask at all. While they fail to restrict air flow, the porous fabric actually breaks up the bigger particles into many little droplets that are more likely to hand around in the air longer.

The researchers suggest that the larger view takeaway is that masks do work in cutting down the transmission of COVID-19. Because some masks are highly effective while others are counterproductive, we should make sure to choose the facial coverings that best protect ourselves and our community.

Click here for a video summary put together by the research team at Duke.