BS EN 12021:2014 Respiratory Equipment – Compressed Gases for Breathing Equipment

BS EN 12021 is the key European standard specifying the quality requirements for compressed gases supplied for use in breathing apparatus and respiratory protective equipment. The standard establishes limits for contaminants and defines the quality criteria necessary to ensure that compressed breathing air does not present a risk to the wearer.

Whilst often associated with breathing apparatus used by firefighters and emergency responders, the standard is equally important wherever compressed air-fed respiratory protective equipment (RPE) is used in industry. This includes spray painting operations, confined space working, abrasive blasting, chemical processing, pharmaceutical manufacture and many other applications where workers rely upon a supplied-air breathing system for protection.

For occupational hygienists, LEV professionals and employers, BS EN 12021 provides an important reminder that supplying air to a respirator is only effective if that air itself is safe to breathe.

What This Resource Covers

This resource explains:

The purpose of BS EN 12021
Breathing air quality requirements
Compressed air contamination risks
Air-fed respiratory protective equipment (RPE)
Compressed breathing air testing
Breathing air monitoring requirements
The relationship between BS EN 12021 and COSHH
Practical implications for employers and duty holders

Who Should Read This Resource?

This resource is particularly relevant for:

Occupational Hygienists and Health & Safety Professionals
LEV Designers, Commissioners and Test Engineers
Employers and Duty Holders
Respiratory Protective Equipment (RPE) Programme Managers
Compressed Air System Operators and Maintenance Engineers
Anyone responsible for supplying breathing air to workers

Source Document

View the HSE guidance here:

View Original HSE Guidance

Source: British Standards Institute (BSI)
Document Type: European Standard EN
Status: Current
Last reviewed by LEVCentral: June 2026

Why This Guidance Matters

In many workplaces, respiratory protective equipment forms the final line of defence when exposure cannot be adequately controlled by elimination, substitution, process modification or Local Exhaust Ventilation.

Where air-fed respiratory equipment is used, workers place complete trust in the quality of the air supplied to them. If the compressed air system becomes contaminated, the breathing air intended to protect the worker can become a source of exposure itself.

BS EN 12021 was developed to ensure that compressed breathing air remains suitable for human respiration and free from contaminants that could cause toxic, harmful or adverse health effects. The standard specifies limits for contaminants including carbon monoxide, carbon dioxide, oil and water, whilst also addressing oxygen content, odour and taste requirements.

The Importance of Breathing Air Quality

Many industrial compressed air systems were never intended to provide breathing-quality air.

Potential contamination sources include:

Compressor lubricant carry-over
Vehicle exhaust emissions
Carbon monoxide contamination
Carbon dioxide contamination
Moisture and condensation
Intake contamination from nearby processes
Deterioration of filtration equipment

Without suitable purification, monitoring and testing arrangements, these contaminants may be delivered directly to the respirator wearer.

Breathing Air and COSHH

BS EN 12021 aligns closely with the principles of COSHH.

Where employers provide air-fed respiratory protective equipment, they must ensure that the supplied air is safe to breathe and suitable for its intended purpose. Guidance supporting the standard highlights the need to keep contaminants as low as reasonably practicable and references Workplace Exposure Limits contained within EH40.

The standard therefore forms an important part of a wider respiratory protection programme and should not be considered in isolation from exposure assessment, RPE selection and maintenance activities.

Testing and Monitoring

The standard highlights the importance of regular breathing air quality testing.

Testing programmes typically assess:

Oxygen concentration
Carbon monoxide
Carbon dioxide
Oil contamination
Water content
Odour and taste characteristics

Where breathing air systems are used routinely, periodic testing provides assurance that filtration systems remain effective and that contamination has not entered the compressed air supply.

Further Resources

Related LEVCentral Resources:

Recommended Learning

M200 Basic Principles of Occupational Hygiene
M501 Measurement of Hazardous Substances
P601 Thorough Examination and Testing of LEV Systems
P604 Performance Evaluation and Management of LEV Systems

Thought Leadership

Many organisations focus heavily on selecting appropriate respiratory protective equipment but devote considerably less attention to the quality of the air being supplied to that equipment.

BS EN 12021 reminds us that effective respiratory protection depends not only on the respirator itself, but also on the integrity of the breathing air supply. In many workplaces, compressed air systems represent a critical safety barrier. Like any control measure, they require routine monitoring, maintenance and verification if they are to continue protecting workers effectively.

Good occupational hygiene is not simply about providing protection—it is about ensuring that every element of the protection system performs exactly as intended.