What sensitivity level indicates that smoke detectors must be recalibrated or replaced?

The correct answer identifies a sensitivity level threshold that indicates when smoke detectors require recalibration or replacement. Specifically, the marked sensitivity range for smoke detectors is crucial for their optimal functioning. When detectors fall outside this specified sensitivity range by an amount greater than 0.25%, this indicates that they may not perform effectively in detecting smoke, potentially leading to unsafe conditions.

Maintaining sensitivity within these guidelines is essential for ensuring that smoke detectors operate correctly, providing the intended safety for occupants in a building. Therefore, if the sensitivity is outside the acceptable range by 0.25% or more, it is a clear signal that action is needed, which can include recalibration or complete replacement of the device. This proactive approach helps ensure that smoke detectors are reliable and efficient in their life-saving role.