The oxygen level alarm usually goes off if oxygen levels are below what percentage?

The oxygen level alarm is commonly set to trigger when oxygen levels fall below 19.5 percent, which is the identified threshold for safe breathing air according to regulatory standards. At this percentage, the atmosphere may be considered oxygen-deficient, which can lead to various health risks and impair the ability to perform tasks safely.

Monitoring oxygen levels is crucial in environments where there is potential for displacement of oxygen by other gases or when activities, such as confined space entry, are taking place. If the oxygen concentration dips below 19.5 percent, it signals a hazardous condition that requires immediate attention to ensure the safety of individuals working in or around those environments. Higher percentages, such as 20.5 or 21.0, are considered safe for typical atmospheric conditions and are not triggers for alarms; thus, the focus for the alarm system is at the 19.5 percent threshold.