It depends on the region. This sort of study is still greatly needed in places. Like Australia, where the official statement is: "Surgical masks in the community are only helpful in preventing people who have coronavirus disease from spreading it to others. If you are well, you do not need to wear a surgical mask as there is little evidence supporting the widespread use of surgical masks in healthy people to prevent transmission in public" [ https://www.health.gov.au/resources/publications/coronavirus... ]

Check out Australian news sites to see all the maskless people.