Updated: Aug 10, 2020
Here are a few links to studies about stopping the spread of COVID-19 by wearing masks.
https://www.youtube.com/watch?v=jMLGyL5neik From DW news out of Germany (12 min.)
https://www.youtube.com/watch?v=wshkM1mkBOU for those who feel claustrophobic while wearing a mask (11 min.)
https://www.youtube.com/watch?v=dbAzUUtqbiU a short visual on droplets (30 sec.)
I realize that there are downsides to wearing masks, but for many people, wearing a mask is not an all day affair. Don't wear a mask when not needed as at many outside environments, in a private vehicle or at home with family members at low risk But when people are in close quarters with others it seems obvious to me that by putting up a barrier in front of one's nose and mouth, there will be less transmission because there will be less of one's breath floating around and for a shorter distance. Also while wearing a mask, one is much less likely to touch his or her mucous membranes and thus would reduce the spread through contaminating surfaces.
Please check out my google posting about what kind of mask NOT to wear: https://local.google.com/place?id=17826428544317784046&use=posts&lpsid=7047652113524587815