Sustaining life in hazardous environments...
Sustaining life in hazardous environments...

What is EN12021 and why do we Air Quality Test?

19th September 2018

Compressors that produce Breathing Air either to be supplied directly to users or to refill cylinders must produce air to the EN12021 standard, and tested as appropriate to confirm this. The quality of air from compressors can vary substantially and it is important to ensure that you are certain that the air being supplied is suitable to be supplied for breathing air purposes.

Why do we air quality test?

The easiest way to appreciate the main reasons why we air quality test is to outline the different requirements of EN12021 and highlight the key reason that this is part of the standard

Test Element


Reason for Test


Free from unsatisfactory odour or taste

Unusual odour or taste is distracting and unpleasant for users and can often point to an underlying problem


21% ± 1%

Low oxygen presents a risk of asphyxiation whilst high oxygen enhances a flammability risk

Carbon Dioxide


Whilst carbon dioxide is present in the air we breathe at high levels it can cause intoxication or poisoning and so needs to be monitored

Carbon Monoxide


Carbon monoxide initially causes headaches, dizziness and vomiting but as levels increase it will result in a loss of consciousness and death



A presence of oil in the air supply will contaminate and damage breathing apparatus, as well as leading to ill health if inhaled or ingested by the wearer

Water – Airline <40bar

Where apparatus is used and stored at a known temperature the pressure dewpoint shall be at least 5⁰C below likely lowest temperature. Where conditions of usage and storage of any compressed air supply is not known, the pressure dewpoint shall not exceed -11⁰C

Water in breathing air is not dangerous itself to the wearer, but the concern is that if free water is able to form this could result in internal corrosion or the freezing of valve components, leading to a malfunction of equipment

Water – High Pressure

40 to 200bar ≤50 mg/m3

>200bar ≤35mg/m3

HP Charging Compressor ≤25mg/m3


To ensure the suitability of the breathing air from either a fixed installation or a mobile set up regular Air Quality Testing should be performed. Static systems should be tested at least once every 3 months, and systems that are moved more frequently than this should be tested every time that they are relocated or if environmental surroundings change significantly.

There are a variety of methods employed for testing air quality with the most popular being a detection tube test. This is a quick and easy test to perform that gives a reasonably accurate indication of any issues with air quality. The other method being employed is to have the air analysed by a laboratory test, which although more accurate is not used as much as it takes a lot longer and costs significantly more. However other methods are now available and units such as the AirTrackTM can be installed into any mobile or fixed set up and give a real time readout of air quality. They can use this data to activate an alternative supply or switch a unit off if air quality is compromised ensuring that users are not exposed to contaminated air.

It is important that everyone using compressed breathing air understands the importance of maintaining suitable air quality and the consequences of not doing so, to ensure that everyone involved in the use of the air produced is kept safe form both immediate and long term health conditions.

For advice and further details on a particular system that you have please contact us – 0844 915 1111

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