CC-127 AAS-Physical and Biological Collection Efficiencies - Application Note - Rev B (US)

Sep 27, 2026

Application Note CC-127 describes physical and biological collection efficiency testing for the TSI AeroTrak+ Remote Active Air Sampler (AAS) Model 7010 used in GMP pharmaceutical and medical cleanroom monitoring. It explains how standards such as ISO 14698-11 and EN 17141:2020 guide evaluation, distinguishing physical efficiency (particle-size collection) from biological efficiency (viable microbe collection and viability losses). The document defines d50 value and impaction velocity, then details test procedures and results that determine overall sampler performance for aseptic processing environments.

LanguageEnglish

CategoryHealthcare

FormatPDF

Pages9

Reading Time23 min

AccessFree to download

Introduction—Microbial Air Sampling for Pharma

Background—Evaluating Air Samplers

Calculation of the d50 Value—Proof in Testing

Test Procedures for the Experimental Determination of the d50 Value

Experimental d50 Value Results

Conclusions—Meet the Needs of Pharma Aseptic Processing

References

PHYSICAL AND BIOLOGICAL COLLECTION EFFICIENCIES TSI AEROTRAK+ REMOTE ACTIVE AIR SAMPLER MODEL 7010 APPLICATION NOTE CC-127 (5/6/2021) Rev B (US) Contents Introduction—Microbial Air Sampling for Pharma .................................................................................. 1 Background—Evaluating Air Samplers ......................................................................................................... 2 Calculation of the d50 Value—Proof in Testing............................................................................................ 4 Test Procedures for the Experimental Determination of the d50 Value ..............................................4 Experimental d50 Value Results............................................................................................................................ 7 Conclusions—Meet the Needs of Pharma Aseptic Processing............................................................... 8 References................................................................................................................................................................ 9 Introduction—Microbial Air Sampling for Pharma As part of good manufacturing practice (GMP) compliance, medical and pharmaceutical manufacturing operations must qualify and routinely monitor microbial contamination levels in cleanrooms and clean spaces such as isolators and restricted access barrier systems (RABS) . The use of active air samplers (AASs) is an essential part of this process. Even though impaction-based microbial samplers have been in use since the middle of the 20th century, currently there is no standard defining minimum performance requirements. As a result, there are significant differences in performance for AASs in use today, which can lead to improper evaluation of cleanroom microbial contamination levels. Therefore, proper characterization of microbial air sampler performance is a critical aspect of a contamination control program. While no standards currently define minimum performance levels for AASs, ISO 14698-11 and EN 17141:20202 (which is scheduled to replace ISO 14698-1) provide recognized guidance regarding active air sampling equipment and validation. These standards describe two ways to evaluate the collection efficiency of microbial air samplers: physical efficiency and biological efficiency. Physical efficiency defines how well the sampler collects different sizes of particles, regardless of the composition of the particles (inanimate, microorganisms, or microbe-bearing) . The biological efficiency defines how well the sampler collects viable microbe-bearing particles which can form colony-forming unit (CFU). It includes the losses caused by both the physical efficiency and the effect that the sampling has on the viability of the microorganisms due to stressing during collection and dehydration of the media. While physical efficiency can be measured using biological particles, often it is measured using polystyrene latex spheres (PSL) or other non-viable particles. Biological efficiency is measured using microbes. Annex E of EN 17141 provides a formula to calculate the d50 value, or physical efficiency, for AASs using impaction. In addition, Annex B of ISO 14698-1 and Annex E of EN 17141 define procedures that can be used to measure the physical and biological efficiency of a sampler. TSI recently introduced a new AAS—the TSI AeroTrak®+ Remote Active Air Sampler (AAS) Model 7010. It uses external vacuum to draw air through the AAS. With an impaction velocity of 43 m/s, the AAS is designed to provide high physical and biological efficiency over a broad range of particle sizes. This document describes testing that was done to determine the performance of AeroTrak+ Remote AAS, and includes complete test results. Background—Evaluating Air Samplers The efficiency of a sampler can be defined as the number of particles captured in the sampler d

FAQs

What are physical efficiency and biological efficiency in microbial air sampling?

Physical efficiency describes how well the sampler collects particles across different sizes, independent of particle composition. Biological efficiency describes how well it collects viable microbe-bearing particles that can form CFUs, including losses from physical collection and viability stress during sampling.

How is the d50 value used to evaluate an active air sampler?

The d50 value (impactor cut point) is the aerodynamic equivalent particle size at which 50% of particles are collected and 50% pass by the culture medium. Lower d50 indicates higher overall efficiency at capturing smaller particles.

Why is impaction velocity important for determining sampler performance?

Impaction velocity affects the size of particles that impact the culture medium: higher velocity captures smaller particles but can damage cells and reduce viability, while lower velocity may fail to capture viable particles. It is therefore a compromise influenced by sampler geometry and d50 behavior.

Sep 27, 2026

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