ultrafilter inc., of Norcross, Ga., offers a portable breathing air system called ultrapure ALG 20. It provides a convenient and economical solution where compressed air is centrally pre-purified and carbon monoxide (CO) and carbon dioxide (CO2) concentrations in the compressed air do not exist. This system provides healthy breathing air, which passes into the breathing masks via a pressure-reducing valve. With a volume flow rate of 35 cfm, the system can provide breathing air for up to four people.