In highly sensitive industries like pharmaceuticals, biotechnology, microelectronics, and healthcare, even the smallest airborne particles can have significant consequences. That’s why particle count testing is a vital component of cleanroom validation, quality control, and contamination prevention protocols.
But what exactly is particle count testing, and why is it essential?
What is Particle Count Testing?
Particle count testing is a method used to detect and measure the concentration and size of airborne particles in a controlled environment, such as a cleanroom or sterile area. This test helps ensure that the environment meets required cleanliness standards—typically defined by ISO 14644-1, EU GMP, or Federal Standard 209E.
The process is carried out using a particle counter, an instrument that samples air and detects particles based on their size (typically ranging from 0.1 to 10 microns).
Why Particle Count Testing is Important
1. Ensures Compliance with Cleanroom Standards
Cleanrooms are classified based on the number and size of particles allowed per cubic metre of air. Particle count testing verifies whether the room meets its designated classification, such as ISO Class 5 or Class 7.
2. Protects Product Integrity
In pharmaceutical or semiconductor manufacturing, airborne contamination can compromise product quality or even render it unusable. Regular testing ensures that contamination stays within acceptable limits.
3. Supports Sterility in Healthcare Settings
In operating theatres, ICUs, and isolation wards, maintaining air cleanliness is critical. Particle count testing can help prevent healthcare-associated infections (HAIs).
4. Monitors Environmental Changes
Testing can detect system failures, improper gowning, or increased traffic flow that might affect air quality—allowing teams to act quickly before it escalates.
How is Particle Count Testing Performed?
Step 1: Determine Sampling Locations
Based on room size and layout, specific sampling points are selected as per ISO 14644-1 Annex A guidelines or a risk-based approach.
Step 2: Use a Particle Counter
A calibrated air particle counter (handheld or remote) is used to collect air samples at each location. These devices detect and count particles by laser diffraction or light scattering methods.
Step 3: Measure Particle Sizes
Common size channels include 0.3 µm, 0.5 µm, and 5.0 µm. The data is compared to the allowable limits based on the cleanroom’s classification.
Step 4: Document and Analyse Results
Results are documented and analysed to identify trends, abnormalities, or areas needing corrective action. If the particle count exceeds limits, root cause analysis is triggered.
Cleanroom Classifications and Particle Limits (ISO 14644-1)
| ISO Class | ≥0.5 µm particles/m³ |
|---|---|
| ISO 5 | 3,520 |
| ISO 6 | 35,200 |
| ISO 7 | 352,000 |
| ISO 8 | 3,520,000 |
Note: Pharmaceutical and medical device environments may also follow EU GMP Grade A–D classifications.
When Should You Conduct Particle Count Testing?
Initial Cleanroom Qualification
Routine Environmental Monitoring (e.g. monthly or quarterly)
After Maintenance or Renovation Work
During Root Cause Investigations
To Validate HVAC or HEPA Filter Performance
Factors That Affect Particle Counts
Number of personnel present
Type of gowning used
Equipment operation and air turbulence
Air change rate (ACH) and filtration efficiency
Maintenance of HEPA filters and HVAC systems
Choosing the Right Equipment
Select a calibrated particle counter that meets:
ISO 21501-4 compliance
Sufficient flow rate (e.g., 1.0 CFM or 28.3 LPM)
Capability to record multiple size channels
Built-in reporting features
Advanced systems may integrate with building management systems (BMS) or provide real-time data logging for continuous monitoring.
Final Thoughts
Particle count testing is not just a regulatory requirement—it’s a quality assurance tool that protects your product, your environment, and ultimately, your customers. Whether you're managing a cleanroom, validating a medical facility, or manufacturing in a controlled setting, routine testing is critical to maintaining your operational excellence.
Need help with cleanroom particle testing or ISO 14644-1 certification? Partner with a certified testing provider to ensure your facility remains compliant, efficient, and safe.
