What is the minimum required oxygen level in a vault for safety?

The minimum required oxygen level in a vault for safety is 19.5%. This standard is based on health and safety guidelines that indicate oxygen levels below this threshold can pose significant health risks, including loss of consciousness or impaired judgment. A level of 19.5% ensures that there is enough oxygen in the air for safe respiration under normal conditions.

When oxygen concentrations drop below this level, individuals may experience symptoms such as dizziness, confusion, or even asphyxiation in extreme cases. Therefore, maintaining an oxygen level of 19.5% or higher is crucial for the safety of personnel who may enter enclosed or confined spaces, such as vaults.

Other options listed reflect either levels that are too low, which can lead to unsafe conditions, or levels that exceed normal atmospheric conditions but are not required for basic safety standards.