From Certification to Continuous Control: Rethinking Particle Monitoring in Cleanrooms

Cleanrooms are designed for control. They are classified, validated, and certified to meet strict particle limits under ISO standards and regulatory guidance such as EU GMP Annex 1.

But certification is a snapshot in time.

Between those formal qualification events, real-world variables take over. Personnel move in and out. Equipment is added or repositioned. Maintenance occurs. Airflow patterns shift. And contamination events rarely announce themselves before they become a deviation.

That is why particle monitoring deserves more attention than it often gets. Not as a regulatory checkbox, but as a core component of a proactive environmental monitoring strategy.

Certification Proves a Moment. Monitoring Protects What Happens After.

ISO classification confirms that a room meets defined particle limits under controlled test conditions. It validates the design and performance of the space at that specific moment.

What it does not do is guarantee stability over time.

In pharmaceutical and biotech manufacturing, especially in aseptic processing environments, small increases in non-viable particles can be early indicators of:

• HEPA filter integrity issues
• Airflow disruption or imbalance
• Improper gowning practices
• Equipment placement affecting laminar flow
• Door or transfer activity impacting pressure cascades

When particle monitoring is treated as periodic verification rather than continuous oversight, facilities are often reacting after the fact.

Continuous particle monitoring shifts the posture from reactive investigation to early detection.

Why Particle Data Is More Than a Compliance Metric

Regulations increasingly emphasize ongoing environmental control. Annex 1, in particular, reinforces the importance of continuous viable and non-viable monitoring in Grade A and B areas during operations.

But beyond regulatory alignment, particle data plays a strategic role in risk management.

Trending particle counts over time can help teams:

• Identify gradual degradation in cleanroom performance
• Correlate particle spikes with specific operational activities
• Strengthen root cause investigations
• Support batch release decisions with objective environmental data

In advanced manufacturing environments, data is not just archived. It is analyzed.

Particle monitoring becomes most powerful when it contributes to process understanding, not just audit readiness.

The Limitation of Episodic Testing

Many facilities still rely heavily on portable particle counters during room certification, requalification, or when investigating a deviation.

Portable testing has an important role. It verifies classification and supports controlled studies. But it is inherently episodic.

It captures defined test points under defined conditions.

What it does not provide is:

• Continuous visibility during production
• Real-time alarms when thresholds are exceeded
• Automatic trending over weeks or months
• Immediate correlation with other environmental variables

In high-risk manufacturing environments, episodic testing leaves gaps between data points. And those gaps are where issues can develop unnoticed.

The Case for Integration: Context Changes Everything

A standalone particle counter generates data.
An integrated particle monitoring strategy generates insight.

When particle counts are monitored alongside:

• Differential pressure
• Temperature
• Relative humidity
• Airflow
• Door open/close events

you gain context.

For example, a temporary particle increase may correspond directly with a pressure fluctuation or high-traffic period. Without integrated data, teams are forced to reconstruct events manually.

With integrated monitoring, the system tells a more complete story.

This is where technology partnerships matter.

Through our partnership with Beckman, we integrate industry-recognized particle counting technology directly into the Rees Monitoring System. That integration allows facilities to capture real-time particle data within the same validated platform used to monitor other critical environmental parameters.

The result is not just another instrument in the room. It is unified environmental oversight.

What to Look for in a Particle Monitoring Strategy

For pharma and biotech organizations evaluating or upgrading their particle monitoring approach, several factors are worth considering:

1. Accuracy and Reliability
The particle counter must meet applicable ISO standards and perform consistently in controlled environments.

2. Continuous Monitoring Capability
Especially in Grade A and B areas, continuous monitoring during operations may be necessary to meet regulatory expectations.

3. Data Integrity
Electronic records should support secure data storage, audit trails, and alignment with 21 CFR Part 11 requirements where applicable.

4. Alarm Management
Thresholds should be configurable and tied to meaningful response procedures.

5. Integration with Environmental Monitoring Systems
Particle data should not live in isolation. Integration enables trending, correlation, and faster investigations.

6. Service and Calibration Support
Ongoing performance depends on proper maintenance and calibration. Support infrastructure matters.

Particle monitoring is not simply about acquiring equipment. It is about building a defensible, data-driven environmental control strategy.

A Broader View of Environmental Control

Cleanroom performance depends on many interrelated factors. Air filtration, pressure cascades, humidity control, personnel flow, and equipment layout all contribute to the stability of the environment.

Particle monitoring provides a measurable signal when something changes.

When that signal is continuously captured, properly trended, and integrated with other environmental data, it becomes part of a larger quality narrative.

In today’s regulatory landscape, that narrative matters. Inspectors increasingly expect not just proof of compliance, but evidence of control.

Continuous particle monitoring, supported by reliable instrumentation and a unified monitoring system, helps demonstrate that control in a clear and defensible way.

Frequently Asked Questions

1. Is continuous particle monitoring required in all cleanrooms?

No. Requirements depend on room classification and regulatory guidance. For example, Annex 1 emphasizes continuous monitoring in Grade A and B areas during operations. Lower-grade areas may rely on periodic testing, depending on risk assessments and process design.

2. What is the difference between portable and continuous particle monitoring?

Portable particle counters are typically used during certification, requalification, or investigations. Continuous monitoring systems are installed in fixed locations and collect data in real time, often integrated into an environmental monitoring system with alarms and trending capabilities.

3. How does particle monitoring support root cause investigations?

When particle data is continuously recorded and trended, teams can correlate spikes with other environmental changes such as pressure fluctuations, door activity, or operational events. This provides objective data to support deviation investigations and corrective actions.

4. Does particle monitoring data need to meet 21 CFR Part 11 requirements?

If particle data is used to support GMP decisions, batch release, or regulatory documentation, it may need to comply with electronic record and signature requirements such as 21 CFR Part 11. Integration into a validated monitoring platform can help address these expectations.

5. How often should particle counters be calibrated?

Calibration frequency depends on manufacturer recommendations, internal SOPs, and regulatory expectations. Annual calibration is common, but some organizations implement more frequent verification depending on risk and usage.

Bringing It All Together

Particle monitoring is not just about meeting a requirement. It is about maintaining control in environments where small changes can have significant consequences.

When particle data is continuously captured, properly integrated, and supported by reliable instrumentation, it becomes part of a larger quality strategy. It helps teams detect shifts early, investigate with confidence, and demonstrate sustained control over critical environments.

At Rees Scientific, we have partnered with Beckman, one of the industry’s most respected particle counter manufacturers, to deliver a fully integrated solution. By combining Beckman’s proven particle counting technology with the Rees Monitoring System, we provide facilities with real-time visibility, centralized data management, and the support infrastructure needed to maintain performance over time.

If you are evaluating your cleanroom monitoring strategy or looking to strengthen how particle data fits into your broader environmental program, we would welcome the conversation.

Contact Rees Scientific to discuss how an integrated particle monitoring solution can support your cleanroom operations.

https://reesscientific.com/request-an-assessment