As students return to school and employees head back to the office all with new safety protocols likely including wearing a mask, a new study from Duke University explores which masks are more effective.
Spoiler alert: A fitted N95 mask, usually reserved for those in the medical community, performed the best in their test. However, since many Americans do not have access to those and have been using a mix of store-bought or homemade cotton and fabric facial coverings, Duke tested 13 other kinds of masks.
The study, which was published Friday, was prompted when a professor at Duke’s School of Medicine was asked to assist a local group buying masks in bulk for the community. According to CNN, the professor wanted to make sure the masks they bought were effective.
Researchers gathered 14 kinds of masks, including the professionally-fitted N95 mask, a bandana, homemade cotton varieties, and a surgical mask. They then used a dark room, laser beam and cell phone camera to record how many droplets (which reflect the laser beam light) each mask allows through.
For each mask test and the non-mask wearing control test, the speaker was recorded saying “Stay healthy, people” five times. Each mask was tested ten times.
The surgical mask performed second-best, behind the fitted N95 mask. The selection of homemade cotton masks all performed within a similar range. There was a big difference in material, with knitted fabric allowing more particles to pass through.
Meanwhile, bandanas and neck fleeces, or neck gaiters, were not as effective.
“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,” the researchers note.
The CDC recommends wearing face coverings to stop the spread of Covid-19, which can spread through droplets expelled from the mouth while breathing, speaking, singing, etc.
The University of Washington’s Institute for Health Metrics and Evaluation projects that 67,000 American lives would be saved between now and December 1 by near universal wearing of masks. They released their figures just last week.