The Atlantic:

If you feel confused about whether people should wear masks and why and what kind, you’re not alone. COVID-19 is a novel disease and we’re learning new things about it every day. However, much of the confusion around masks stems from the conflation of two very different functions of masks.

Masks can be worn to protect the wearer from getting infected or masks can be worn to protect others from being infected by the wearer. Protecting the wearer is difficult: It requires medical-grade respirator masks, a proper fit, and careful putting on and taking off. But masks can also be worn to prevent transmission to others, and this is their most important use for society. If we lower the likelihood of one person’s infecting another, the impact is exponential, so even a small reduction in those odds results in a huge decrease in deaths. Luckily, blocking transmission outward at the source is much easier. It can be accomplished with something as simple as a cloth mask.

At the beginning of all of this, there was a lot of confusion regarding masks. Now it’s generally accepted that everyone should wear them, even homemade cloth masks, at all times when outside your home. Because, as the story points out, “Models show if 80% of people wear masks that are 60% effective, easily achievable with cloth, we can get to an effective R0 of less than one. That’s enough to halt the spread of the disease.”