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ISO 14644 Specification: Outlining Cleanroom Standards for Quality Assurance

In the complex world of cleanroom standards, the ISO 14644 Specification is the cornerstone of guidance, ensuring uniform stringent measures for maintaining cleanliness and quality in controlled environments. In this article we’ll introduce ISO 14644, its evolution, and compliance considerations.

What is ISO 14644?

ISO 14644 is an international standard that establishes the classification of air cleanliness in cleanrooms and controlled environments. It meticulously outlines the allowable particle counts, emphasizing the critical role of clean air in diverse sectors.

The ISO 14644 specification is paramount in setting the benchmark for cleanroom classification globally. Its significance lies in providing a standardized, uniform approach to maintaining a contaminant-free environment, crucial for industries like pharmaceuticals, electronics manufacturing, biotechnology, research & development, aerospace, and more.

History of ISO 14644

The journey of ISO 14644 began with the need for a unified system for cleanroom classification. Prior to the adoption of ISO 14644 in 1999, the US FED-STD-209E standard defining allowable particle counts in cleanrooms and clean-zones was the predominant standard, which was officially retired in Nov 2001. Over time, ISO 14644 has undergone several revisions to adapt to advancements in technology and a deeper understanding of contamination control.

The evolution of ISO 14644 reveals how it has kept pace with the ever-changing landscape of cleanroom technologies and new manufacturing requirements. Each revision brings refinements, reflecting the industry’s commitment to staying at the forefront of cleanliness standards.

Understanding Cleanroom Classifications

Cleanrooms are categorized into classes based on the maximum allowable particle count per cubic meter, with particle size being measured in microns. ISO 14644 divides these classes into ISO 1 through ISO 9, with ISO 1 being the most stringent and ISO 9 the least.

Maximum Number of Particles per Cubic Meter – ISO 14644



≥0.2µm ≥0.3µm ≥0.5µm ≥1µm ≥5µm



ISO 1 10 2
ISO 2 100 24 10 4
ISO 3 1,000 237 102 35 8 Class 1
ISO 4 10,000 2,370 1,020 352 83 29 Class 10
ISO 5 100,000 23,700 10,200 3,520 832 293 Class 100
ISO 6 1,000,000 237,700 102,000 35,200 8,320 2,930 Class 1,000
ISO 7 352,200 83,200 29,300 Class 10,000
ISO 8 3,520,000 832,000 293,000 Class 100,000
ISO 9 35,200,000 8,320,000 Room Air

Several factors, including air cleanliness, temperature, and humidity will dictate the necessary classification of cleanrooms. Understanding these factors and the unique requirements of your manufacturing processes is crucial for selecting the desired cleanliness level.

ISO 14644 Compliance

ISO 14644 compliance assures a high level of quality in manufacturing processes. It minimizes the risk of product contamination, contributing to consistent and reliable production outcomes. Businesses that adhere to ISO 14644 standards gain international recognition for their commitment to cleanliness and quality.

Compliance with ISO 14644 involves meeting specific requirements regarding airborne particulate concentrations. From monitoring particle counts to implementing efficient filtration systems to ensuring proper airflow volume, adherence to these requirements is paramount.

While the benefits of ISO 14644 compliance are substantial, businesses often face challenges during implementation. Overcoming these hurdles requires a comprehensive understanding of the standard, avoiding the pitfalls leading to contamination, and a strategic approach to implementation.

Implementing best practices is key to achieving and maintaining ISO 14644 compliance. This includes periodic audits and recertification, regular monitoring of particle counts, maintenance of filters and HVAC equipment, thorough training of personnel, routine inspection of process equipment, and investing in state-of-the-art cleanroom technologies to monitor and control airflow.

Periodic Audits and Recertification

Regular audits and recertification are critical in ensuring ongoing compliance. Periodic reviews help identify areas for improvement, keeping cleanroom facilities in optimal condition. Typically, annual recertification is all that is required, though depending on your application, environment, manufacturing processes, and cleanliness rating, more frequent certification may be necessary to ensure compliance.

Monitoring Particle Counts

Though not required in every application, having particle counters within your cleanroom can serve as an early warning system letting you know when it’s nearing time for maintenance. Routinely check logs, or better, store them in a central control system reviewed on a weekly basis to ensure that your cleanroom continues to function optimally and stays within the design specifications.

Regular HVAC and Filter Maintenance

Ensuring that all HVAC equipment is functioning correctly will ensure that the cleanroom receives the required amount of airflow necessary to maintain pressure. Monitoring differential pressure across prefilters serves as a method of knowing when your prefilters are starting to get clogged and in need of replacement. Routine testing of your HEPA or ULPA filters using a balometer or similar equipment will indicate how clogged the filters are and when they are in need of replacement.

Proper Gowning and Personnel Training

Personnel are the number one source of cleanroom contamination. It is critical that personnel be thoroughly trained on proper gowning procedures, which pieces of attire are required, proper workplace attire (e.g., no clothing or footwear that can shed fibers, no makeup or jewelry, etc.), and while a no-brainer, food and drink are obviously not permitted within the cleanroom.

Co-compliance with Other Standards

ISO 14644 harmonizes with various other international standards related to cleanrooms. It is important to note any additional requirements related to your cleanroom application, as this may include other standards like cGMP or BSL. These additional requirements need to be considered during engineering to avoid costly rework or retrofit.

Future Compliance

As technology evolves, so do cleanroom requirements. The standard continues to adapt to emerging technologies, ensuring it remains relevant in the face of industry advancements. With the pace of technological innovation, the anticipation of future revisions to ISO 14644 is high. Staying informed about potential updates is crucial for businesses seeking long-term compliance.



  1. Is ISO 14644 applicable only to manufacturing industries? ISO 14644 is applicable to a wide range of industries, including pharmaceuticals, electronics, healthcare, and aerospace. It sets cleanliness standards for controlled environments beyond just manufacturing.
  2. How often should cleanrooms undergo audits for ISO 14644 compliance? Regular audits are essential, and the frequency depends on factors like the industry, cleanroom class, and specific operational requirements. Typically, audits should be conducted at least annually.
  3. What are the consequences of non-compliance with ISO 14644 standards? Non-compliance can lead to product contamination, compromised quality, and regulatory issues. It may also impact a company’s reputation and market access.
  4. Are there specific training programs for ISO 14644 compliance? Yes, various training programs and courses are available to educate personnel on ISO 14644 compliance. These programs cover protocols, standards, and best practices.
by Pacific Environmental Technologies January 19, 2024