Before COVID-19 hit the United States, most face masks (i.e. surgical face masks) were found in the healthcare sector. The original purpose of the surgical face mask was to protect surrounding people from the wearer. For example, protecting patients with open wounds from the rest of the people in the operating room58 or tuberculosis patients wearing a mask to prevent spread of the disease through airborne droplets.59
Today, we can walk around a grocery store and see many different kinds of face masks because studies show that wearing a face covering reduces the chance of transmission of coronavirus.60 But with shortages of surgical and N-95 masks, people have resorted to alternatives like homemade cotton masks, bandanas and neck gaiters.
A recent study by Duke University investigates the efficacy of these alternatives in order to help guide the public’s mask selection.
In the study, a subject wears a face mask and speaks towards an expanded laser beam inside a dark enclosure. Respiratory droplets that pass through the face covering scatter the laser beam light and are recorded with a cell phone camera. They then used a computer algorithm to count the droplets in the recording. This method was done on a variety of commonly available masks.
The study found the following:
- N95 masks were the most effective, allowing no droplets to pass.
- Handmade cotton masks were as effective as surgical masks, both only allowing a very small number of droplets to pass.
- Bandanas and neck gaiters were found to be the least effective, both transmitted a higher droplet count than control tests with no masks used.
So, why are bandanas and neck gaiters worse than no mask at all?
Martin Fischer, PhD, the chemist and physicist who developed this testing method explained that these types of masks have become a popular choice in the United States because they are easy to wear and more breathable than other options- this could explain why they also do not offer much protection. Fischer explained that the fabric used for bandanas and neck gaiters are quite porous, which essentially breaks up respiratory particles into smaller ones and creates the higher droplet count that the study reports.
Click here to read the full study.