Air Quality Testing

The use of compressed air as a source of breathable air is well accepted throughout industry. In recent years, employers have become increasingly aware of their responsibility to comply with International Breathing Air Standards. The standards define the quality of breathing air that must be provided to operators working in contaminated environments.

For compressed air to be suitable for breathing air applications it must be properly purified to ensure that it meets the relevant Breathing Air Standard. Breathing air standards are published by a number of regional approval bodies. The breathing air advice, and any purifiers supplied by, Compressed Air Solutions are designed to comply with the following international standards;

• Europe EN 12021 • UK BS 4275: 1997 • USA CGA G7.1-1997 • OSHA-Grade D

Reference has also been made to the British Compressed Air Society Fact Sheet No. 304 Breathing Air

Where a potential inhalation hazard exists it is essential that a full assessment be made of the potential risk to the user. The assessment should not only identify the potential risk of contamination to the breathing air supply, but also the level of potential contamination.

In the event of being unable to either remove the contamination risk or to control the risk, it is the employers responsibility to introduce measures to ensure that the breathing air supply complies with the required air quality standard.

The air quality used in a breathing air system must be controlled under all operating conditions, including the possibility of a plant or process failure. In addition to conforming with the required compressed air quality it must also be ensured that the delivered air flow rate is at least sufficient to meet the foreseeable needs of the total number of users at their maximum work rate consumption.


Contaminant Levels and Testing

The applicable standard for the country of use will not only detail the maximum allowable levels of contaminants but also give an indication of the selection criteria for protection devices.

If doubt exists about the potential of a possible contaminant then steps must be taken to either monitor the air quality or install a suitable purification device to ensure compliance with the standard.

BS EN 12021 “Respiratory protective devices – Compressed air for breathing apparatus” is now the only standard to indicate contaminant levels for breathing air both in the UK and in the EU).


Substance Extract from BS EN 12021 – Clause 6.
Contaminants – Compressed air for breathing apparatus shall not contain any contaminants at a concentration, which can cause toxic or harmful effects. In any event all contaminants shall be kept to as low a level as possible and shall be far below the national exposure limit.
Oxygen (21 ± 1) % by volume (dry air)
Carbon monoxide As low as possible but not to exceed 15ml/m3 (formerly BS 4275 specified 5ml/m3)
Carbon dioxide 500ml/m3
Oil mist Lubricants (droplets or mist) 0.5 mg/m3
Odour/taste Without significant odour or taste
Water (liquid) There should be no free liquid water


For the measurement of any or all of the contaminants, reference should be made to the ISO 8573 series. The series identifies measurement methods, which can be done either on-site or in a laboratory.

Compressed Air Solutions expert technicians use Factair safe-air testers to test for carbon dioxide, carbon monoxide and oxygen with the Draeger oil impactor for oil mist.