What type of breathing protection is required if oxygen levels in the air are at 15 percent?

When oxygen levels in the air drop to 15 percent, the environment is considered oxygen-deficient, which poses a serious risk for anyone entering that space. In such situations, a supplied air respirator is essential. This type of equipment provides a continuous supply of breathable air from an external source, ensuring that the wearer receives sufficient oxygen to breathe safely.

Supplied air respirators are designed specifically for use in environments where oxygen levels are below safe thresholds, as they completely bypass the ambient air. This ensures that the individual is protected from not only low oxygen levels but also potentially harmful contaminants if present.

In contrast, other types of breathing protection, such as air-purifying respirators and powered air-purifying respirators, are not suitable in conditions of low oxygen concentration. They rely on filtering the air that is present, which is not effective or safe in oxygen-deficient environments. Therefore, the only suitable option in situations of severely low oxygen levels is a supplied air respirator, making it the correct choice for this scenario.