Cleanroom Monitoring Basics: Particle Counters, Air Sampling & Trending

Published: 2026-01-15

In pharmaceutical and cleanroom environments, monitoring supports compliance and process control. The goal is not just “pass/fail” — it is to detect changes early, maintain confidence in controlled areas, and support investigations when deviations occur.

1) Non-viable monitoring: Particle counters

Particle counters measure airborne particles by size and concentration. They help assess cleanliness and can be used for routine monitoring or troubleshooting spikes.

• Where used: room classification checks, routine monitoring points, critical zones.
• Common formats: portable particle counters and online/continuous monitoring systems.

2) Viable monitoring: Active air sampling

Active air samplers collect airborne microbes over a defined air volume. This supports microbiological EM programs, especially in regulated manufacturing environments.

• Where used: viable sampling at defined locations as per SOP.
• Key factor: consistent sampling method and placement.

3) Build a practical monitoring routine

1. Identify critical locations: points near operations, pass-throughs, and high-traffic areas.
2. Set frequency: based on SOP and risk (daily/weekly/monthly).
3. Trend results: look for drift — not only exceedances.
4. Maintain equipment: calibration, cleaning and consumables planning keeps data reliable.

4) Common mistakes to avoid

• Collecting data without trending or review (missed early warning signs).
• Sampling at inconsistent locations and heights (incomparable results).
• Skipping calibration/maintenance (questionable data integrity).

Practical takeaway

• Use particle counters for non-viable monitoring and air samplers for viable monitoring.
• Define locations and frequency in SOP and keep sampling consistent.
• Trend results to detect early drift and maintain control.