Overview of Air Sampling
Microbiological air sampling is used to assess the quality of ambient air and ventilation systems within controlled environments.
It measures the concentration of viable microorganisms, including bacteria, fungi and yeasts, helping identify potential contamination risks and ensuring safe operating conditions.
Air sampling is commonly used in healthcare environments and supports compliance with HTM 03-01 guidance, particularly in areas where air quality is critical.
Microbial air monitoring
HTM 03-01 Compliant
Critical area testing
Reliable lab results
Applications and environments
Air sampling may be carried out in a range of environments, including:
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Ultra-clean operating theatres (UCV theatres)
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General surgical and treatment rooms
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Critical care areas
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Cleanrooms
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Decontamination and packing areas
It can be used in any area where ventilation performance and microbiological air quality need to be assessed.
Purpose of air sampling
Microbiological air sampling is used to assess the effectiveness of ventilation systems and identify potential contamination risks within controlled environments.
It helps to:
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Confirm air quality in critical areas
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Detect viable microorganisms present in the environment
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Support infection prevention and control
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Provide microbiological evidence where required
Air sampling is not always mandatory, but is often recommended in environments where ventilation plays a key role in maintaining safe conditions, and may be advised by a Ventilation Safety Group (VSG).
Sampling process
A qualified engineer attends the site to carry out sampling at selected locations.
The process involves:
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Using specialist air sampling equipment
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Drawing a measured volume of air (typically up to 1000 litres)
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Capturing microorganisms onto agar plates
This allows airborne microorganisms to be collected for further analysis.
Sample analysis
Samples are analysed in our in-house UKAS-accredited laboratory using appropriate culture media, such as TSA agar, to recover general microorganisms and potential pathogens.
Where required, we can:
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Enumerate yeasts and moulds separately
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Identify specific microbial species present
This provides a clear and reliable assessment of microbiological air quality.
HTM 03-01 and compliance
HTM 03-01 provides guidance on specialised ventilation systems within healthcare environments.
Air sampling can support compliance by:
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Verifying microbiological air quality
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Supporting ventilation system assessments
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Providing evidence for audits and inspections
While not always required, it is often used alongside ventilation testing to provide a more complete understanding of environmental performance.
Frequently Asked Questions
Air sampling is not always mandatory but is recommended in critical environments where air quality plays a key role in infection control.
It measures the number of viable microorganisms present in the air, usually reported as colony forming units (CFU) per volume of air.
Common causes include poor ventilation, inadequate cleaning, high foot traffic, or environmental contamination.
Results depend on incubation times, but typically take a few days as microorganisms need time to grow before being counted and analysed.
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