Researchers compared the sprays of droplets we spew out of our mouths when wearing a one-layered cloth mask, two-layered cloth mask, surgical mask, and no mask at all — while talking, coughing, and sneezing.
Mashable sums up the findings succinctly:
The study's big takeaways are:
• When talking, wearing even a single-layer mask significantly limits the exhalation of droplets.
• For coughing and sneezing, a double-layer mask is much more effective than a single-layer mask.
• Generally, the more layers a mask has the better. The researchers suggest "at least three layers" and found surgical masks performed best in this study — though not everyone has access to these masks.
For more details read the published results in Thorax.