If a worker's exposure time-weighted average (TWA) exceeds the PEL, what action is typically required?

If a worker's exposure time-weighted average (TWA) exceeds the PEL, what action is typically required?

• A. Do nothing
• B. Stop operations and evacuate
• C. Implement controls and follow procedures
• D. Only perform additional biomonitoring

Answer: (C)

When a worker’s TWA exceeds the PEL, the priority is to bring exposure back under the limit by applying controls and following established procedures. The PEL sets the maximum allowable average exposure over a work shift, so an exceedance signals that the current process or conditions aren’t adequately protecting people. Address this by using the hierarchy of controls: first, engineering controls such as enclosing the process or adding local exhaust ventilation to remove contaminant at the source; then administrative controls like altering work schedules, rotating tasks, or changing procedures to lower exposure; and use PPE only as a supplementary measure if needed. After implementing these controls, perform follow-up exposure monitoring to confirm the level is now below the PEL. Biomonitoring alone doesn’t reduce the airborne concentration, and stopping operations or evacuating is reserved for imminent, acute hazards rather than routine exceedances.

When a worker’s TWA exceeds the PEL, the priority is to bring exposure back under the limit by applying controls and following established procedures. The PEL sets the maximum allowable average exposure over a work shift, so an exceedance signals that the current process or conditions aren’t adequately protecting people. Address this by using the hierarchy of controls: first, engineering controls such as enclosing the process or adding local exhaust ventilation to remove contaminant at the source; then administrative controls like altering work schedules, rotating tasks, or changing procedures to lower exposure; and use PPE only as a supplementary measure if needed. After implementing these controls, perform follow-up exposure monitoring to confirm the level is now below the PEL. Biomonitoring alone doesn’t reduce the airborne concentration, and stopping operations or evacuating is reserved for imminent, acute hazards rather than routine exceedances.