People who’ve tried to exercise outside wearing a mask other than a neck gaiter have come to the unsurprising conclusion that they find it harder to breathe. The neck gaiter, made of very thin, stretchable material, addresses that problem, allowing exercisers to get as much air as they need. Unfortunately, investigators with Duke University also found that neck gaiters provide no protection against coronavirus disease 2019 (COVID-19) and that wearing them may be worse than wearing no face covering at all when it comes to stopping the spread of the virus. The findings were published in a study in Science Advances.
Neck gaiters weren’t the only face coverings tested: in all 14 were analyzed, from N95s (unsurprisingly judged to be the most effective in containing COVID-19 spread) to bandanas (not much more effective then neck gaiters, according to the study).
As a news release from the university explains, the disconcerting discovery about neck gaiters came about as a result of a Duke professor wanting to find out what are the most effective face coverings. That professor needed the information in his effort to provide masks and other face coverings to an underserved population in Durham, N.C.
Enter Martin Fischer, a chemist and physicist at the university. He constructed a simple testing device using a laser (you can find them online for about $200), a cell phone camera, a cardboard box, and a lens. Fisher was able to track particles emitted by individuals.
The investigators noted that “In brief, an operator wears a face mask and speaks into the direction of an expanded laser beam inside a dark enclosure. Droplets that propagate through the laser beam scatter light, which is recorded with a cell phone camera. A simple computer algorithm is used to count the droplets in the video.”
After testing the 14 masks that were considered commonly available, they found some fascinating tests. First and—again—not surprisingly, N95 respirators and surgical masks provided the most protection/containment of droplets.
Cotton masks performed quite well, which is reassuring as they are frequently used in the community. Two important findings were also reported: “We noticed that speaking through some masks (particularly the neck fleece) seemed to disperse the largest droplets into a multitude of smaller droplets … which explains the apparent increase in droplet count relative to no mask in that case. Considering that smaller particles are airborne longer than large droplets (larger droplets sink faster), the use of such a mask might be counterproductive. Furthermore, the performance of the valved N95 mask is likely affected by the exhalation valve, which opens for strong outwards airflow.” The emphasis on valved N95s is a good reminder about the role of exhaust valves and how they not only provide poor source control, but also cannot be used in sterile environments.
The findings of this study are not only informative in terms of the potential amplification done by neck fleece masks but reiterates the importance of infection preventionists making informed decisions for the community in terms of masks. Ideally, surgical masks would be helpful as they offer protection for not only those around the wearer, but also for the person wearing them.
As hospitals consider more sustainable approaches to ensure masking compliance in visitors but also want to support employees beyond the walls of the healthcare facility, cloth masks might pose a viable option. Moreover, providing the public with better guidance on masks that offer more protection while not impacting healthcare supply chains, is beneficial to all. More insight into the efficacy of widely available masks is immensely important.
