No employee should be exposed to lead at concentrations greater than how many micrograms per cubic meter of air in an eight-hour period?

The correct value indicating the maximum allowable concentration of lead that an employee should be exposed to during an eight-hour period is 50 micrograms per cubic meter of air. This threshold helps protect workers from the detrimental health effects associated with lead exposure, which can include neurological impairments and other systemic health issues.

Regulatory agencies, such as the Occupational Safety and Health Administration (OSHA), establish such standards to ensure safe working conditions, particularly in environments where hazardous materials are present. Maintaining exposure below this concentration is crucial for minimizing the risk of lead-related illnesses.

While the other listed concentrations exceed the safe limit, the focus on the 50 micrograms per cubic meter aligns with established workplace safety regulations designed to safeguard employee health over time.