The study found a disparity in the amount of protection some masks offered.
Duke researchers concluded the most effective mask was the N95. The Centers for Disease Control and Prevention said that N95 are not only masks, but respirators that filter out at least 95% of particles in the air. N95s also fit more securely than a regular face mask does, allowing for minimal leakage.
Other masks that performed well in the test were three-layer surgical masks and cotton masks.
The poor performers in the study were folded bandannas and knitted masks, according to researchers.
In some cases, certain types of masks made particle exposure even worse, according to the study. The study’s authors said that neck fleeces, also known as gaiter masks, were the least effective of all. Neck fleeces were shown to break down larger droplets into smaller particles, which can more easily slip through and out.
Below are the range of masks that the Duke study tested:
The experimental set up had a person wearing a face mask speaking in the direction of a laser beam inside a dark box. Then the amount of droplets that scattered in the beam were recorded with a cell phone camera. The data was then counted using an algorithm.
For more on the charts and findings of the Duke University mask experiment, read the full study here.