Passive and Active Air Sampling in Effective Environmental Monitoring

By Andy Whittard

With the latest draft revision of EU GMP Annex 1 demonstrating the highest standards in patient safety, all healthcare businesses, that make use of cleanrooms in their manufacturing and production activities, are paying fresh attention to their environmental monitoring policies. This draft revision is also considered a big step towards creating a recognised global standard for the maintenance of cleanroom environments; hence the level of detail.

If your business is one of the many that will be affected by this latest draft revision of the EU GMP Annex 1 once it is published, you are no doubt exploring ways to ensure your EM measures are efficient, effective and compliant. As soon as the revision is passed and published, there will be a short period of time in which to ramp up your processes for compliance to ensure that you have an effective environmental monitoring program and meet international standards. Your microbial air sampling process is one such area you should pay attention to.

Microbial air samplers are a staple piece of equipment in cleanrooms and play a critical role in maintaining confidence in an aseptic environment. Regardless of which specific industry sector your business falls within, to achieve the best results, all cleanroom operators need to employ both active and passive equipment for accurate measurements.

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Passive environmental monitoring is the most basic requirement

Passive sampling is performed with settle plates which are your standard Petri dishes filled with prepared culture media. These are left open to allow colonies of bacteria to settle and develop. The results can then be counted, and you can measure the viable biological particles in the air and microbial contaminants.

This method of EM and its test results are not quantitative in that it cannot capture and detect smaller particles suspended in the air and it cannot sample specific volumes of air. Depending on the level of contamination, settle plates do not always provide accurate data to drive improvements and solutions. But they are cost-effective and require only minimal additional equipment, such as settle plate stands or plate carriers.

Active environmental monitoring offers precision

Active monitoring is an accurate way of measuring any contamination in the air. To perform active EM, an air sampler draws in a specified, known volume of air, through or over a particle collection device, such as an agar plate. The culture is then placed in incubation and analysed which will give insight into information such as the bacterial or fungal count and the colony forming units.

A product such as the ImpactAir® slit-to-agar sampler can allow a greater sample volume to be collected and offers a continuous monitoring solution. It can also be adapted to suit specific deployment needs.

Active air sampling will give you a quantitative result and most modern air samplers are easy to use and deploy for general environmental monitoring applications. Portable samplers, such as the SAS Super 180, allow users to quickly sample at multiple locations within a cleanroom. The SAS range of microbial air samplers have a programmable delay start function as standard. A delayed start allows any impact or environmental contamination from the operator to be ‘cleaned’ from the area. This helps to ensure that the operator setting the samples doesn’t influence the sample result.

A sampling system for isolator cabinets or Grade A filling lines

To monitor within isolator cabinets or Grade A filling lines, you will need a sampling system to sit permanently inside the cabinet, with the control unit placed externally.

As an added precaution, in the instance of isolator cabinets, you need to limit the number of transfers to reduce the risk of contamination. In the filling lines, you should control the number of interventions to mitigate contamination. An installed system can help to greatly reduce these transfers and interventions and therefore the associated risks.

Making sure you have the right air samplers for your business

Conducting an audit of your current equipment and needs will help to focus on the features and benefits of any new samplers you’re considering adding to your environmental monitoring protocol.

There are many important factors to consider before deciding on an air sampler, as these will determine the viability of the micro-organisms that are collected. To ensure you receive the correct level of confidence and assurance from your sampling, you must ascertain:

  • The characteristics (type, size) of the particles you want to be sampled
  • The sensitivity of those viable particles to the sampling procedures you have in place
  • The estimated concentration of the collected particles
  • The collection efficiency of each sampler
  • The appropriate prepared culture media you must use
  • The ambient conditions of the sampled area
  • Whether the sampler has the right airflow velocity for low levels of viable particles

Consideration should also be given to what is the appropriate sample you are looking to collect.  For example, in your sampling plan, do you wish to collect 1m3 as quickly as possible because of the high number of sample points, or will it need to be collected more slowly so as to sample the air continuously throughout the operation of the aseptic process. Also make a note of the accuracy of the data each sampler is guaranteed to collect, whether it is easy to handle and implement in your operation, and that it is easy to keep clean and sterilised.

The EM process and equipment you use must be able to provide you with an accurate representation of your environment

To ensure you can trust the output and data retrieved from your process and samplers, you must have your equipment properly validated and calibrated.

Your EM process and equipment must address your challenges and have all the features necessary to ensure the risk of contamination is mitigated.

Your aseptic processes and EM equipment must be suited to the size of your manufacturing area, with the most effective number of sample points. You must be able to perform a risk assessment, to inform a sampling regime and make use of both active and passive methods for sample capture.



The Environmental Monitoring Processes and Validation Guide

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