A bridge has been scheduled for rehab and painting. All metal is to be sandblasted to near-white conditions. According to OSHA, respirators with continuous flow air lines are required to cover the wearers ___?

A bridge has been scheduled for rehab and painting. All metal is to be sandblasted to near-white conditions. According to OSHA, respirators with continuous flow air lines are required to cover the wearers ___?