A safety consultant described a client doing abrasive blasting on pre-cast concrete with beaded glass media. The employer had layered on substitution, engineering controls (isolated areas, media replacement), administrative measures (wetting, boundaries, minimal staffing), airline respirators with an assigned protection factor of 1,000, and full body suits. Even so, 8-hour TWA results consistently came back above the silica PEL (before accounting for respirators). The question: is quarterly monitoring really required forever when the results will likely never change?
OSHA explained that under the scheduled monitoring option, employers must conduct initial monitoring and follow-up assessments at intervals driven by the results, and monitoring must be performed every three months as long as exposures remain above the PEL (29 CFR 1910.1053(d)).
The practical relief is the performance option. An employer may switch to it provided the air monitoring data already collected are sufficient to accurately characterize current employee exposures, considering factors like exposure variation, work practices, and equipment condition. Under either option, exposures must be reassessed after changes in production, processes, controls, personnel, or practices that could create new exposures.
OSHA also reiterated that where exposures exceed the PEL after implementing all feasible controls, the employer is required to provide the appropriate level of respiratory protection (29 CFR 1910.1053(g)(1)(iii)).