What you need to know.
BE EN 4275-1997 has been superseded by BS EN 529-2005 and this is currently under review. The BS EN 529-2005 Standard is a guide to “Respiratory protective devices, recommendations for selection, use, care & maintenance”. Part of this is the requirement for the control of breathing air contamination.

An air fed mask or the point at which the air fed device is connected to the general compressed air system should be tested to have a minimum standard as opposite…………………………………….

is