Sampling — Check the Film

Purpose and Limits of Viable Environmental Monitoring

Viable environmental monitoring provides a time-specific view of recoverable microbial contamination:

• Evaluate engineering controls, cleaning and disinfection, material handling, and aseptic practices.
• Use results to identify weaknesses and guide improvement.
• Interpret findings within the sampling method and conditions.

Selecting Methods and Building the Sampling Plan

A documented, risk-based plan connects sample collection with specific contamination questions:

• Distinguish active viable air sampling, contact plates, and supplemental settle plates.
• Define sample volume, dynamic conditions, frequencies, suitable media, and neutralizers.
• Document exact locations, methods, and baseline conditions.
• Reassess the plan when rooms, equipment, or processes change.

Choosing Meaningful Sampling Locations

Personnel movement, material flow, and touch frequency help identify informative sampling sites:

• Observe actual work instead of choosing locations only for convenience.
• Trace repeated personnel and material movements.
• Consider pump keypads, scale controls, and other surfaces that transfer contamination to gloves.
• Record unexpected touch points during walkthroughs.

Collecting and Identifying Samples

Consistent collection and handling protect sample usefulness:

• Control active-air volume, positioning, equipment cleaning, and handling near exposed media.
• Collect contact samples before disinfecting the selected surface and use a new plate for each sample.
• Remove residual agar through a reviewed, surface-appropriate cleanup method.
• Define settle-plate exposure and record the date, time, location, and operator.

Interpreting Results and Investigating Changes

Comparable results and location-specific trends provide more context than isolated counts:

• Use action levels appropriate to the sampling method and ISO classification.
• Establish facility alert levels to identify earlier deterioration.
• Track counts and contamination recovery rates, including the proportion of samples with growth.
• Investigate people, equipment, methods, and the environment; use follow-up monitoring to evaluate corrective actions.