How to Prepare for Cleanroom Certification: Steps Before, During, and After Testing

Cleanroom certification is a crucial step in ensuring the safety, compliance, and optimal performance of your controlled environment. 

Whether your facility supports pharmaceutical production, semiconductor manufacturing, or aerospace assembly, certification confirms that your cleanroom meets its designated ISO 14644 classification and operates in accordance with the required air cleanliness standards.

The process can feel complex. It involves detailed cleanroom testing, documentation, and coordination between facility managers, engineers, and third-party certifiers. However, with the right preparation and a suitable partner, it doesn’t have to be overwhelming.

In this blog, we’ll walk through what to expect before, during, and after cleanroom certification. You’ll learn how to prepare your facility, understand the key testing steps, and maintain compliance through ongoing recertification.

What Is Cleanroom Certification and Why Does It Matter?

Cleanroom certification is the formal process of verifying that a controlled environment meets its intended ISO 14644 classification for particle cleanliness and performance. 

• It’s not the same as initial commissioning or validation.
• Validation occurs during the design and construction stages, confirming that the cleanroom was built to meet performance specifications.
• Certification, on the other hand, happens after the cleanroom is operational. It’s the ongoing verification that your environment continues to meet those standards in real-world conditions.

During certification, third-party professionals conduct a series of cleanroom tests to assess air cleanliness, airflow, pressure differentials, and other environmental factors that directly impact product quality and compliance. The results are documented in a certification report that provides both proof of compliance and insight into areas for improvement.

Maintaining a valid certification isn’t just about passing an audit. It’s about protecting your processes, products, and personnel. Regular certification ensures:

• Your cleanroom’s environmental conditions consistently meet ISO and industry-specific standards (e.g., GMP, FDA).
• Equipment and filtration systems are functioning correctly to control contamination.
• Your facility avoids production downtime, rework, or failed audits.

If you want to take a deeper look at the specific tests used to determine cleanroom classification, check out our related blog:

4 Steps to Take Before Cleanroom Certification

Preparation is the key to a smooth, successful cleanroom certification. The more proactive you are before testing begins, the more efficient (and accurate) the process will be. 

Here are the essential steps facility managers and engineers should take to get ready:

1. Review Current Performance Data

Identify trends or potential issues that could affect your certification results.

• Start by reviewing your cleanroom’s recent environmental monitoring and maintenance records.
• Look at airflow readings, pressure differentials, particle counts, and temperature or humidity data.

2. Schedule Preventive Maintenance

A well-maintained cleanroom is much more likely to pass testing the first time.

• Before the certifier arrives, ensure all systems are operating at peak performance.
• Replace or clean HEPA/ULPA filters, inspect seals and gaskets, verify the calibration of monitoring equipment, and perform a thorough cleaning of all surfaces.

3. Confirm Documentation and Records

Up-to-date documentation is crucial for both certification and future audits. 

• Review your calibration logs, SOPs, maintenance records, and cleaning protocols.
• If you’ve made any modifications to the cleanroom or its equipment, ensure that these changes are reflected in your documentation.

4. Coordinate with Your Certification Partner

Your certifier will need access to specific areas and equipment during cleanroom testing. 

• Work with them in advance to schedule testing times, coordinate staff availability, and ensure any necessary production pauses or system shutdowns are planned.

Angstrom Technology offers pre-certification consultation and readiness assessments to help identify potential problem areas early, ensuring your facility is fully prepared for testing day.

What Happens During Cleanroom Testing and Certification

Once your cleanroom is ready, the certification process begins. This stage involves a series of standardized cleanroom tests designed to verify that the environment meets the performance requirements for your target ISO classification. 

These tests are performed using calibrated instruments and precise protocols to ensure accuracy and repeatability.

Here’s what you can expect during testing:

Airborne Particle Count Testing

This test measures the concentration of airborne particles within the cleanroom to confirm compliance with your ISO class. 

• Technicians use particle counters to assess air cleanliness in multiple sample locations across the space.

HEPA/ULPA Filter Integrity Testing:

Filters are the backbone of contamination control. 

• This test checks for leaks or damage in your filtration system using an aerosol challenge and photometer scan, ensuring air entering the cleanroom is filtered correctly.

Airflow Velocity and Uniformity Testing:

Proper airflow keeps contaminants from settling and ensures consistent air exchange throughout the cleanroom. 

• Technicians measure air velocity at multiple points to confirm uniform distribution and verify the correct number of air changes per hour (ACH).

Room Pressurization and Recovery Testing:

These tests confirm that the room maintains the required pressure differential between clean and less-clean areas in the cleanroom. 

• The cleanroom needs to be able to quickly return to acceptable particle levels after exposure events.

Temperature and Humidity Verification:

Environmental stability matters for both comfort and product integrity. 

• This test confirms that your HVAC and control systems maintain the required temperature and humidity range for your operations.

When cleanroom testing is complete, your certifier will compile all results into a certification report summarizing compliance, deviations (if any), and recommendations for corrective action.

At Angstrom Technology, our certification technicians follow ISO 14644 and IEST RP-CC006 guidelines, using precise, calibrated instruments to deliver accurate, audit-ready results.

Post-Certification: Maintaining Cleanroom Compliance

Earning your cleanroom certification is a major accomplishment, but maintaining that performance is an ongoing responsibility. 

Once testing is complete, you must review results, address any findings, and plan ahead for continuous compliance.

Here’s what to focus on after certification:

1. Review Your Certification Report

Your certification report will include detailed data from each test, notes on compliance status, and any deviations or recommended actions. 

• Review the findings carefully with your team and certification partner.
• Ensure you understand the results and identify any areas that require improvement.

2. Address Corrective Actions Quickly

If the report identifies deficiencies, such as minor air leaks, equipment calibration issues, or out-of-range particle counts, you’ll need to develop and document a corrective action plan. 

• Taking prompt action ensures compliance and also prevents minor issues from turning into costly failures.

3. Plan for Recertification

Most cleanrooms must be recertified at least once per year. Some industries (like pharmaceutical or aerospace) require more frequent testing. 

• Schedule your next certification in advance to avoid downtime or noncompliance gaps.

4. Maintain Performance Between Certifications

Ongoing environmental monitoring, routine maintenance, and periodic testing help keep your cleanroom performing consistently. 

• Regularly track airflow, temperature, humidity, and pressure differentials, and log all data for easy reference during audits and inspections.

Angstrom Technology offers comprehensive validation and recertification services, ensuring your facility remains compliant throughout the year. 

How Angstrom Simplifies the Certification Process

Preparing for and maintaining cleanroom certification requires precision, documentation, and expertise. Angstrom Technology helps clients navigate this process seamlessly—from pre-testing preparation to post-certification support.

Here’s how we make certification easier and more reliable:

• Pre-Certification Readiness Assessments – Before testing begins, Angstrom’s team conducts a thorough evaluation of your cleanroom’s current performance. We identify potential issues like airflow inconsistencies, filter degradation, or documentation gaps, and provide recommendations to ensure your facility is fully prepared for certification day.
• Comprehensive ISO Testing and Documentation – Our certified technicians perform all required cleanroom testing in accordance with ISO 14644 and IEST standards. Every test is performed using calibrated instruments, and results are compiled into a detailed, audit-ready certification report.
• Ongoing Recertification and Maintenance Support – We provide scheduled recertification services, preventive maintenance, and environmental monitoring to help clients maintain compliance year after year.
• A Single Source for Compliance Confidence – Working with multiple vendors can lead to inefficiencies, miscommunication, and inconsistent results. Angstrom streamlines everything under one roof so your cleanroom stays compliant, efficient, and ready for audit at all times.

Whether you need certification for a new facility or ongoing support for an existing one, Angstrom Technology will ensure your cleanroom operates to the highest standards.

Certified Today, Compliant Tomorrow — and Every Day After

Cleanroom certification isn’t just a one-time milestone; it’s a continuous commitment to quality, safety, and operational excellence.

By preparing your facility, understanding the testing process, and keeping up with regular recertification, you can ensure consistent performance and regulatory compliance year after year.

Whether you’re certifying a new facility or maintaining an existing one, having the right partner makes all the difference. At Angstrom Technology, we help clients simplify every stage of certification with expert testing, proactive maintenance, and precise documentation. 

Ready to schedule your next certification or learn how Angstrom can support ongoing compliance? Contact our team today to get started.