Atmosphere-supplying respirators provide the greatest respiratory protection. They let you breathe air from an outside source, such as an air tank or a compressor. They are used where oxygen levels may dip below 19.5% or where certain gases and vapors are highly concentrated.
An air-line respirator provides air through a hose attached to an outside supply. The air may come from a compressor or a tank. Air then flows into the mask as you breathe. A self-contained breathing apparatus (SCBA) allows you to move while carrying an air supply (usually on your back). Air flows from a tank into the mask. The tank must hold enough air to allow at least 30 minutes of use. A combination respirator provides air through a hose from a stationary source in a similar fashion to the air-line respiration. The combination respirator also includes a small air supply tank similar to the scuba set. The user will use this tank in the event of failure of the stationary source.
Read the steps to the right. Atmosphere-supplying respirators have a mask that's worn like a half-mask or full-face respirator. But instead of a filter or cartridge, an air line fits into the mask. Full-face masks may need special attachments to hold eyeglasses. And, be aware that facial hair, skin problems, certain dental work, and other factors may prevent a good fit.
Inspect your respirator each time before you put it on for cracks, dents, torn straps, or broken fittings. Inspect all hoses. Check that the air tank is full or that the compressor is working. Ensure that hazardous gases, vapors, fumes, or other contaminants are kept away from the air supply. Wash the mask in warm water with a mild soap. Or follow instructions from your employer or the manufacturer. Rinse in water. Then dry with a lint-free cloth or let it air-dry. When not in use, place the mask in a bag, and store in a cool, dry place.