Breathing Air

In recent years, employers have become increasingly more aware of their responsibility to comply with breathing air standards and regulations. The most commonly specified standard for the prescription of breathable air is BS 4275:1997 ‘Guide to implementing an effective respiratory protective device programme’ which was withdrawn on 22 November 2005.

This was then replaced on that date by BS EN 529:2005 respiratory protective devices. Recommendations for selection, use, care and maintenance. Unlike BS 4275 the new standard BS EN 529 does not identify an air purity specification but indicates in annexe A, clause 4.5 that reference be made to BS EN 12021.

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.

Breathing Air Filtration

There are many different types of products available to provide clean and safe air for breathing apparatus.

A complete 5 stage filtration system is recommended to provide clean and safe compressed air that can be used for breathing apparatus. You can purchase each stage of filtration separately or most commonly available are all in one filtration systems.

Air Quality Testing

If your compressed air system is being used for breathing air, you have a legal responsibility as an employer to have regular Air Quality Testing carried out and the correct maintenance plan in place. Compressed air should be tested for the following:

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 less than one-tenth of a national 8 h exposure limit. For breathing air only the limit shall be less than one-sixth of a national 8h exposure limit. For breathing at hyperbaric pressures greater than 10 bar or exposure times greater than 8h levels shall be revised to take into account the effects of pressure and exposure times.
Oxygen	(21 ± 1) % by volume (dry air)
Carbon monoxide	≤5ml/m³ (ppm)
Carbon dioxide	≤500ml/m³ (ppm)
Oil mist	Lubricants (droplets or mist) ≤0.5 mg/m³
Odour / Taste	Without significant odour or taste.
Water (Liquid)	Compressed breathing air shall have a dew point sufficiently low to prevent condensation and freezing. Where the apparatus is used and stored at a known temperature the pressure dew point shall be at least 5 °C below the likely lowest temperature. Where the conditions of usage and storage of any compressed air supply is not known the pressure dew point shall not exceed -11 °C