Why should we wear a mask when we are close to someone: a video case study

To evaluate the effectiveness of the Centers for Disease Control and Prevention (CDC) recommended one- and two-layer cloth face covering against a three-ply surgical mask, we challenged the cloth covering against speaking, coughing and sneezing. The one-layer covering was made using ‘quick cut T-shirt face covering (no-sew method)’ and the two-layer covering was prepared using the sew method prescribed by CDC.

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From the captured video it can be observed that, for speaking, a single-layer cloth face covering reduced the droplet spread but a double-layer covering performed better. Even a single-layer face covering is better than no face covering. However, a double-layer cloth face covering was significantly better at reducing the droplet spread caused by coughing and sneezing. A surgical mask was the best among all the tested scenarios in preventing droplet spread from any respiratory emission. These visualisations show the value of using face masks and the difference between types of masks. Several other factors determine the efficacy of cloth masks such as type of material, the number of layers, the arrangement of different layers and frequency of washing. However, based on the visualisations presented, in case of shortages of surgical masks, a cloth face covering with at least two layers is preferable to a single-layer one. Guidelines on home-made cloth masks should stipulate multiple layers (at least 3). One study showed that a 12-layered cotton mask was as effective as a surgical mask, but a single-layered cloth mask was not protective against beta-coronaviruses.3 There is a need for more evidence to inform safer cloth mask design, and countries should ensure adequate manufacturing or procurement of surgical masks.