Which ventilation method is involved in air-purifying respirators?

Air-purifying respirators operate using the method of filtration of contaminants from the air. This type of respiratory protection device is designed to remove or filter out harmful substances, such as dust, fumes, vapors, and gases, from the air before it is inhaled by the user.

The primary function of an air-purifying respirator is reliant on the use of filters, cartridges, or canisters that capture harmful airborne materials, allowing clean air to pass through for inhalation. This makes it essential for environments where air quality is compromised, enabling users to safely work in conditions with known airborne hazards.

While other methods mentioned, such as external air supply or sealing off contaminants with a mask, are important aspects of respiratory protection in different contexts (like supplied-air respirators or certain tight-fitting masks), they do not pertain to the operation of air-purifying respirators. These respirators specifically focus on filtering the air that is already present in the environment rather than supplying clean air or sealing out contaminants.