It’s pretty simple: where a damn mask
The public health debate on masks is settled, said Joseph G. Allen, director of the Healthy Buildings program at Harvard. When you wear a mask, “You protect yourself, you protect others, you prevent yourself from touching your face,” he said. And you signal that wearing a mask is the right thing to do.
https://www.nytimes.com/interactive/2020/10/30/science/wear-mask-covid-particles-ul.html