Compressors and ambient-air pumps provide Grade D breathing air to workers in environments with low oxygen levels or compromised air quality.

Oil-lubricated air compressors support numerous workers by filling cylinders or tanks for SAR applications. Compressors are often situated in a dedicated room or separate building to prevent entry of contaminated air. Carbon monoxide, created by the heating of oil used with these compressors, can be pulled in through the air intake of this system.Those who usethese compressorsare consequently required to use high-temperature and/or carbon monoxide monitors/alarms.

Electric or air-driven motor pumps are low-pressure portable alternatives to air compressors. They are also situated remotely but use ambient air from the environment. SARs attach to filters and pumps using an airline that moves breathable air to the respirator. Air pumps do not require high-temperature and/or carbon monoxide monitors/alarms.

OSHA requires that both air compressors and air pumps be tested for air purity every six months via samples taken at the connection to the distribution system. This is most likely the area where the breathing air supply hose is inserted.