Application Note – Bioaerosol N.21 – Air Sampling Standard
The FDA Process Analytical Technology (PAT) requires a more efficient and reliable microbiological air monitoring system. The ability to check and to identify possible microbial contamination during the production and process enables companies to take more quick appropriate and immediate measures to avoid economic losses. The new generation of microbiological air samplers and new monitoring procedures improve the efficiency of the measurement of the microbial air quality in clean rooms and controlled areas.
The International Standards
The ISO 14698-1 “Cleanrooms and associated controlled environments – Bio-contamination control” and ISO 14698-2 “Evaluation and interpretation of bio-contamination data” are the latest international standards specific for Clean Room and controlled area.
They both provide the techniques:
(a) for the detection and monitoring of airborne bio-contamination
(b) for the evaluation and qualification of the efficiency of microbiological air samplers
The risk assessment
The HACCP (Hazard Analysis Critical Control Point), FTA (Fault Tree Analysis), FMEA (Failure Mode and Effect Analysis) are used to evaluate the areas at risk, to identify appropriate mechanisms of control, and to establish initial control levels.
The environmental monitoring program
The ISO 14698-1 gives several recommendations:
(a) type and size of viable particles to be collected
(b) sensitivity of the viable particles in function of the sampling procedure
(c) expected concentration of viable particles
(d) capability to detect low or high levels of micro-organisms
(e) type of nutrient media
(f) duration of sampling
(g) positioning of samplers
(h) possible disturbance of the unidirectional air flow of the tested environment by the samplers
(i) the outlet air from the sampler should not contaminate the environment or be re-aspirated by the sampler itself.
The impaction air sampler
Adopting the “impact sampler”, where the air impacts on the agar surface of a plate, the volume of air should be selected appropriately to obtain a clear colony separation and to facilitate the result reading and interpretation. The air flow should not determine the dehydration of the media and the possible stressing of the micro-organisms. The stress of micro-organisms should be considered with attention because it can determine the slow growth or even the death, with consequent false results ad interpretation of the contamination of the involved area.
The calculation should be reported to 1000 litres of air.
A new generation of impaction air sampler and accessories
The air sampler
The news about the portable, battery operated impaction air sampler is the fact that the stainless steel aspiration chamber is totally separated from the body of the unit.
The two or three parts are connected by a cable up to 25 metres long.
It is therefore possible to reach several goals:
(a) to collect the sample inside an isolator, Clean Room or controlled environment with separated external commands to reduce contamination risk and save important space
(b) to guarantee the sterilization of the aspirating chamber of the instrument with the more updated physical or chemical agents like VHP
(c) to connect several air samplers that can be positioned in more critical points of the same area or in different separated environments.
(d) to produce more continuous monitoring to have under control the critical actions of pharmaceutical and biotechnology production like improper aseptic techniques and / or inadequate cleaning agents
(e) to facilitate the sample data collection and recording from a single unit
(f) to connect the unit to a device for the evaluation of the quality of the compressed air
The accessories
(g) The aspirating head of the air sampler may be a source of contamination and its sterility in Clean Room and Isolator must be certified. The “-Head” (International pbi) aspirating head is a disposable head with certified sterility document.
(h) The transfer of the plate (Contact Plate or Petri dish) inside the aspiration chamber of the air sampler may be source of contamination by production staff people. The complete chamber may be pre assembled by a trained microbiologist in aseptic conditions;
(i) The sterility of compressed air and gases used in Clean Room should be monitored by a specific device mounted on the air sampler.
Conclusions
The ISO 14698 standard provides techniques to help the Clean Room and Isolator operator for the detection of airborne bio contamination.
References
ISO 14698-1:2003 “Clean Room and associated controlled environments – Bio contamination control”.
ISO 14698-2:2003 “Evaluation and interpretation of bio contamination data”.
