APR
acronym for air-purifying respirator. Air-purifying respirators function by filtering contaminants from the air. They do not supply oxygen to the wearer. There are two basic types: disposable and reusable. The most common disposable type is the dust filter mask, such as that used for mowing the lawn. The reusable type utilizes a replaceable filter cartridge which can be changed to fit the particular hazard (particulate cartridge vs. gas or vapor cartridge).