What is a key limitation of Air-Purifying Respirators (APRs)?

A key limitation of Air-Purifying Respirators (APRs) is that they cannot be worn in oxygen-deficient atmospheres. APRs work by filtering out contaminants from the air, but they rely on the availability of oxygen in the environment where they are used. If the surrounding atmosphere does not contain enough oxygen (generally below 19.5% oxygen), the respirator will not be effective and could pose a serious risk to the user, as they may not receive enough breathable air.

This limitation is significant in various settings where asphyxiation hazards may exist, such as confined spaces or areas with processes that consume oxygen. Users need to be aware of the atmospheric conditions before using APRs, especially in emergency situations or locations with known hazardous conditions. Understanding the operational limits of these respirators is crucial for ensuring the safety and health of individuals exposed to hazardous environments.