Even the CDC says that masks do prevent the spread of covid. Not sure why so many people have views that mask do not prevent the spread of covid.

The case of 2 hair stylist who attended to 140 customers while positive for covid and wore face mask throughout had 0 transmission. This was captured in the CDC study too.

https://www.cdc.gov/mmwr/volumes/69/wr/mm6928e2.htm