Any business, or industry, that has a requirement for PPE is also mandated to have initial and ongoing education on the reason for, use of, and disposal of the gear.
Since COVID is spread through aerosolized droplets, any barrier will help. However, this type of transmission indicates the dangers involved with removal and disposal of the PPE. Remember they telling us early on not to touch our faces? Every time you touch your mask for any reason you are transferring those organisms from the mask to your hands. Every time you mask slips below your nose you are breathing in everything on the outside of that mask.
This is why we have not seen drops in cases based off the use of PPE.