Cleanroom Classification and Standards: Understanding Iso 14644

Cleanrooms are critical environments that play a pivotal role in industries where stringent control of airborne particles and contaminants is essential. From pharmaceuticals and biotechnology to electronics manufacturing and aerospace, these controlled spaces ensure the production of high-quality, safe, and reliable products. 

To establish consistent standards and guidelines for cleanrooms worldwide, the International Organization for Standardization (ISO) developed the ISO 14644 series of standards. 

In this blog post, we will explore the significance of cleanroom classification and delve into ISO 14644, understanding its role in ensuring cleanroom performance and quality.

Importance of Cleanroom Classification

Cleanroom classification is a fundamental aspect of contamination control. It involves categorizing cleanrooms based on their cleanliness levels to meet specific requirements. 

The classification system serves as a universal language, enabling cleanroom professionals across diverse industries to communicate and uphold standardized guidelines.

This classification is crucial for several reasons. It provides a common framework to assess and compare cleanroom performance across different facilities. By assigning a classification level, cleanrooms can get designed, operated, and maintained to meet specific cleanliness requirements. This ensures consistency and uniformity in cleanroom practices, regardless of the industry or location.

ISO 14644-1 is the core standard in the ISO 14644 series, and it outlines the classification of airborne particulate cleanliness for cleanrooms and controlled environments. This standard sets limits for the maximum allowable concentration of particles of different sizes per cubic meter of air. 

The classification system consists of nine ISO classes, ranging from ISO Class 1 (the strictest) to ISO Class 9 (the least strict). Each ISO class has specific thresholds for particle sizes, ensuring a consistent level of cleanliness is always maintained across cleanroom facilities.

ISO 14644 and Particle Size Considerations

ISO 14644 standards take into account various particle size ranges to evaluate cleanroom cleanliness. The standard acknowledges the diverse requirements across industries and establishes class limits.

Particle size is a crucial factor in cleanroom classification, as different industries have specific concerns related to particle contamination. 

For instance, ISO Class 5 cleanrooms, which are found in pharmaceutical and semiconductor industries, have stricter limits for smaller particles, 0.5 micrometers, and larger. This is because such particles can impact sensitive processes and equipment.

On the other hand, larger particles exceeding 5 micrometers are of concern in ISO Class 7 or 8 cleanrooms, where the focus is more on minimizing visible contamination or reducing the risk of product contamination. 

According to American Cleanroom Systems, setting specific limits for particle sizes ensures that cleanrooms get designed and operated according to the cleanliness requirements of the industry. This helps maintain product integrity and process reliability.

This classification enables cleanroom professionals to adopt comprehensive strategies to minimize particle contamination, considering the specific particle sizes that are most critical in their industry.

Monitoring and Compliance with ISO 14644 Standards

To ensure cleanroom compliance with ISO 14644 standards, routine monitoring and testing are necessary. This helps to verify that the cleanroom maintains the specified cleanliness level and to identify any deviations or potential issues.

One of the key tools for monitoring cleanroom cleanliness is the use of airborne particle counters. These instruments sample the air within the cleanroom and provide real-time data on particle concentration. 

Cleanroom operators can use this information to assess the cleanliness levels and take appropriate actions if deviations from the specified standards get detected.

The particle counters market is expanding due to various aspects, including heightened activity in related industries, the supportive regulatory landscape, and increased attention to quality. 

MarketsandMarkets analysis states that the global particle counters market is expected to reach a value of USD 825 million by 2027, a significant increase from the USD 511 million recorded in 2022, with a CAGR of 10.0% between 2022 and 2027.

Regular performance qualification is also an essential aspect of ISO 14644 compliance. This involves conducting tests and inspections to validate the cleanroom’s ability to meet the specified classification. Performance qualification ensures that the cleanroom continues to perform as intended, providing the necessary level of cleanliness for critical processes.

In addition to particle count monitoring, ISO 14644 also considers other parameters that contribute to cleanroom performance. These parameters include air velocity, airflow direction, air changes per hour, temperature, humidity, and more. 

Cleanroom operators need to monitor and control these parameters to ensure compliance with the standards and maintain the desired cleanroom conditions.

By implementing effective monitoring systems and conducting regular performance qualification, cleanroom professionals can ensure that their facilities meet the required ISO 14644 standards. 

This, in turn, enhances product quality, safeguards sensitive processes, and maintains a controlled environment for critical operations.

Cleanroom Design and ISO 14644

When designing a cleanroom, several factors need to be considered in alignment with ISO 14644 standards. These include airflow patterns, filtration systems, air supply, and control of other environmental variables such as temperature and humidity. 

The goal is to create a controlled environment that minimizes particle generation, prevents cross-contamination, and provides the desired cleanliness level.

ISO 14644 emphasizes the importance of unidirectional airflow in cleanroom design. Unidirectional airflow, also known as laminar flow, directs air in a single direction through High-Efficiency Particulate Air (HEPA) filters and, in general, moves from the ceiling to the floor. 

This airflow pattern helps to prevent particles from settling on surfaces and minimizes the chances of contamination.

Mentioned below are the design strategies used for other different types of cleanrooms:

Static Cleanrooms

In static cleanroom design, the selection of anti-static materials requires special attention for flooring, wall panels, and equipment. This is important to minimize electrostatic discharge and prevent damage to sensitive electronic components.

The cleanroom layout and equipment placement in static cleanrooms is carefully designed to ensure proper grounding and eliminate static buildup, reducing the risk of electrostatic discharge events.

Biohazard Cleanrooms

Design considerations for biohazard cleanrooms include the implementation of robust containment measures such as airlocks, specialized ventilation systems, and strict protocols for waste disposal to prevent the release of hazardous biological agents.

Biohazard cleanrooms often incorporate features like HEPA-filtered exhaust systems and double-door entry systems to maintain negative pressure and prevent the escape of biohazardous materials.

Aerospace Cleanrooms

Aerospace cleanrooms require meticulous design considerations to control and maintain ultra-low levels of particulate contamination. This includes using high-efficiency air filtration systems, ensuring tight seals in doors and windows, and implementing proper gowning and entry procedures to minimize particle ingress.

To meet the requirements of aerospace cleanrooms, careful attention is given to temperature and humidity control to prevent the formation of condensation or moisture that could affect sensitive aerospace components and materials.

Nanotechnology Cleanrooms

Nanotechnology cleanrooms demand stringent design considerations to achieve ultra-low particle levels. This includes utilizing advanced filtration systems such as ultra-low penetration air (ULPA) filters, as well as incorporating specialized tools and equipment with minimal particle generation.

In nanotechnology cleanrooms, the design of air distribution systems is critical to ensure laminar flow and avoid turbulent air currents that could disturb nanoscale processes. Precision temperature and humidity control are also essential to maintain stable conditions for nanoscale research and manufacturing.

Moreover, filtration systems also play a crucial role in cleanroom design. ISO 14644 provides guidelines for the selection and efficiency of air filters to achieve the desired cleanliness levels. 

By following the design guidelines outlined in ISO 14644, cleanroom professionals can create efficient and effective cleanroom facilities. The design parameters ensure that the cleanroom meets the desired cleanliness classification, enabling industries to perform critical processes with confidence and reliability.


Cleanroom classification and standards, particularly ISO 14644, provide a comprehensive framework for establishing and maintaining controlled environments across various industries. 

Understanding the importance of cleanroom classification, particle size considerations, monitoring and compliance, and other parameters outlined in ISO 14644 enables cleanroom professionals to design, operate, and maintain cleanrooms that meet the specific cleanliness requirements of their industry. 

By adhering to these standards and implementing effective monitoring, maintenance, and quality management systems, businesses can enhance product quality, improve process efficiency, and ensure the safety and reliability of their products.