Compressed Air Bacteria Testing

Most regulated sites sample their environmental air as a matter of routine, then overlook the compressed air feeding the same production areas. Millions of viable organisms enter a system through the compressor intake, because intake filters are designed to catch dirt rather than bacteria, yeasts and mould spores.

A well maintained system with the right filtration will remove them. Bacteria testing is how you prove it is still doing so.

IATT takes microbial samples from your compressed air at the point of use and has them analysed by an independent laboratory. Full results can be sent directly to you if required. Testing is most commonly carried out by pharmaceutical, medical device and food manufacturers, where microbial contamination of the final product is a genuine risk to both the batch and the business.

What Our Compressed Air Bacteria Testing Service Includes

• On-site sampling at your point of use, taken while the system runs as normal
• Testing to the method set out in ISO 8573-7
• Analysis by an independent laboratory
• Results reported as colony forming units per cubic metre (CFU/m³)
• Separate culturing for bacteria and for yeasts and moulds
• Full results issued to you for your quality records and audit evidence
• Repeat sampling scheduled alongside your ISO 8573-1 air quality testing

Bacteria testing is often booked at the same time as our compressed air quality testing, so particles, water, oil and microbial content are all covered in a single visit.

Where Microbial Contamination Comes From

Contamination rarely has a single source. The common ones are:

• Ambient air drawn in through the compressor intake, carrying spores and bacteria that intake filters do not remove
• Residual moisture, as even a small amount of condensate left after drying gives organisms the conditions they need to multiply
• Pipework and fittings, where bacteria and fungi colonise internal surfaces, particularly around dead legs and sections where air sits stagnant
• Maintenance work, where poor hygiene during servicing introduces contamination directly into the system

Bacteria can spoil products, consume nutrients or alter the flavour of medications regardless of their form. Yeasts have plenty of productive uses, but unwanted contamination or overgrowth is detrimental to manufacturing processes and to the product itself. Mould is a problem both in piping systems and structurally, and inhaling or touching mould or mould spores can cause reactions in sensitive individuals.

Identifying contamination is the first step to pinpointing the source and eliminating it. A regular testing programme can flag a developing problem long before it stops production.

ISO 8573-7 and Microbial Limits

ISO 8573-7 is the part of the ISO 8573 series that sets out the test method for viable microbiological contaminant content in compressed air. It tells you how to sample and how to report, and it applies to any air in direct or indirect contact with your product, equipment or sterile areas.

What it does not do is set limits. ISO 8573-1 classifies particles, water and oil, but has no purity classes for microorganisms, and there are no ISO figures for what an acceptable CFU/m³ count looks like. In practice most manufacturers apply the limits already established for their environmental monitoring programme, or those set by GMP or their own quality documentation. We will work to whatever limits your process requires, and can advise if you have not set any yet.

Samples are taken by impaction, where air is passed through a sampler onto an agar plate that is then incubated under controlled conditions until colonies develop. Bacteria and fungi are cultured separately on the appropriate media, at different temperatures and over different periods, so both are identified accurately.

Reducing the Risk of Microbial Contamination

• Fit and maintain sterile point of use filters
• Keep moisture traps and dryers serviced, as damp systems grow organisms
• Design out dead legs and stagnant sections when altering pipework
• Clean and validate compressed air pipelines on a set schedule
• Make sure engineers follow hygienic procedures during maintenance

IATT supplies, installs and services compressed air filtration, dryers and condensate management equipment, so if a result comes back high we can help you deal with the cause rather than just recording the number.

Get in touch today to chat to one of our experienced and knowledgeable staff who can help with any technical or other queries you might have. Request a free quote – we’re happy to help.

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Compressed Air Bacteria Testing FAQs