Cleanrooms are controlled environments designed to minimize airborne particles and contamination. Ranging from ISO Class 1 (ultra-clean) to ISO Class 9 (least stringent), these classifications guide industries in creating conditions tailored to their specific needs.
In this blog, we break down each ISO class, explain the significance of cleanroom standards, and show how different industries apply them — from semiconductors to pharmaceuticals.
What is a Cleanroom?
A cleanroom is a controlled environment specifically designed to minimize particulate contamination, pollutants, and other impurities. Cleanrooms maintain extremely low levels of airborne particles, ensuring a sterile or ultra-clean environment vital in industries such as pharmaceuticals, biotechnology, semiconductor manufacturing, and aerospace engineering.
Cleanrooms are characterized by several key features:
- Advanced air filtration systems, including HEPA and ULPA filters, that continuously remove airborne contaminants.
- Specialized construction materials—walls, ceilings, and flooring are made from smooth, non-shedding, and easy-to-clean surfaces that limit particle generation.
- Strict personnel protocols, including gowning procedures and behavioral rules, to prevent contamination from human activity.
Maintaining a cleanroom involves rigorous protocols, including regular cleaning, disinfection, and monitoring to meet specific industry standards. Contamination control is paramount, as even minute particles can adversely impact sensitive processes or products.
The design and maintenance of cleanrooms demands significant investment, as the costs involved cover the infrastructure, specialized equipment, and strict operational protocols. However, the benefits are substantial, ensuring product quality, compliance, and process integrity.
Why Cleanroom Classifications Matter
]Cleanroom classifications are critical because they directly impact the quality and safety of products in many industries. The correct classification ensures that processes occur within acceptable contamination limits, reducing the risk of:
- Product Defects: Even a single particle can render products like microchips or pharmaceuticals ineffective.
- Regulatory Issues: Many industries must comply with strict cleanliness regulations to avoid penalties or loss of certification.
- Financial Loss: Failures in maintaining the right cleanliness can lead to costly product recalls or production delays.
Choosing the wrong cleanroom class could lead to contamination, poor-quality products, and compliance violations, making it essential for businesses to understand and select the appropriate ISO class for their specific processes.
Understanding ISO Cleanroom Classification (ISO 14644-1)
Cleanrooms are classified based on the number and size of particles permitted per cubic meter of air. These classifications standardize cleanliness levels and guide industries in maintaining the appropriate environment for their needs.
The classification system is governed by the International Organization for Standardization (ISO) under ISO 14644-1, which defines cleanroom classes ranging from ISO 1 (most stringent) to ISO 9 (least stringent).
Each class corresponds to a maximum allowable concentration of particles per cubic meter at specified particle sizes. Below is a table summarizing the allowable particle limits for each class:
ISO Cleanroom Classes and Particle Limits
| ISO Class | ≥0.1 µm | ≥0.2 µm | ≥0.3 µm | ≥0.5 µm | ≥1.0 µm | ≥5.0 µm |
|---|---|---|---|---|---|---|
| ISO 1 | 10 | 2 | — | — | — | — |
| ISO 2 | 100 | 24 | 10 | 4 | — | — |
| ISO 3 | 1,000 | 237 | 102 | 35 | 8 | — |
| ISO 4 | 10,000 | 2,370 | 1,020 | 352 | 83 | — |
| ISO 5 | 100,000 | 23,700 | 10,200 | 3,520 | 832 | 29 |
| ISO 6 | — | — | — | 35,200 | 8,320 | 293 |
| ISO 7 | — | — | — | 352,000 | 83,200 | 2,930 |
| ISO 8 | — | — | — | 3,520,000 | 832,000 | 29,300 |
| ISO 9 | — | — | — | 35,200,000 | 8,320,000 | 293,000 |
Note: Values are maximum allowed particles per cubic meter of air.
Cleanroom Classifications Breakdown (ISO 1 to ISO 9)
ISO 1 Cleanroom
An ISO Class 1 cleanroom stands as the pinnacle of controlled environments, maintaining the highest standard of cleanliness among cleanroom classifications.
This ultra-sterile space allows a maximum of only 10 particles per cubic meter at sizes of 0.1 microns or larger. Such stringent control over airborne particles makes ISO Class 1 cleanrooms indispensable in industries where absolute precision, purity, and cleanliness are imperative.
These pristine environments find application in cutting-edge industries such as semiconductor manufacturing, nanotechnology, and specialized biotechnology research. In semiconductor fabrication, for example, where even a single particle could jeopardize the functionality of a microchip, ISO Class 1 cleanrooms ensure the most stringent level of particle control to guarantee flawless chip production.
ISO 2 Cleanroom
An ISO Class 2 cleanroom represents an environment meticulously designed to maintain exceptional cleanliness, allowing a maximum of 100 particles per cubic meter at sizes of 0.1 microns or larger.
While slightly less stringent than ISO Class 1, these controlled spaces remain critical in industries requiring high precision and minimal contamination.
Industries such as advanced semiconductor manufacturing, specific biotechnology research, and sophisticated optics often rely on ISO Class 2 cleanrooms. These environments play a pivotal role in ensuring that processes remain free from contaminants that could compromise product quality or performance.
Though not as ultra-sterile as ISO Class 1, these cleanrooms still offer exceptional control over particulate contamination. They are integral in safeguarding sensitive processes and ensuring the reliability and quality of products across industries where precision and cleanliness are paramount.
ISO 3 Cleanroom
An ISO Class 3 cleanroom represents a highly controlled environment, allowing a maximum of 1,000 particles per cubic meter at sizes of 0.1 microns or larger.
These cleanrooms are fundamental in industries requiring stringent contamination control, such as pharmaceuticals, certain biotechnology sectors, and aerospace engineering.
Precision manufacturing processes, particularly in pharmaceuticals where the utmost cleanliness is vital, often rely on ISO Class 3 cleanrooms.
While not as strictly controlled as ISO Class 1 or 2, these cleanrooms still offer a significantly low particle count, ensuring a controlled environment critical for various manufacturing and research processes. These environments ensure that sensitive products remain free from contamination, meeting the stringent quality standards and regulatory requirements.
ISO 4 Cleanroom
An ISO Class 4 cleanroom is a controlled environment designed to allow a maximum of 10,000 particles per cubic meter at sizes of 0.1 microns or larger. Industries such as pharmaceutical manufacturing, electronics assembly, and optics rely on ISO Class 4 cleanrooms.
These environments ensure that manufacturing processes remain free from contaminants that could compromise product quality or functionality.
Like ISO Class 3, Class 4 is not as strictly controlled as Classes 1 and 2. Nonetheless, ISO 4 Cleanrooms still offer a notably low particle count, providing a controlled environment vital for maintaining product integrity and meeting industry-specific standards. Their role in ensuring high-quality manufacturing processes under controlled conditions underscores their importance across various industries.
ISO 5 Cleanroom
An ISO Class 5 cleanroom is a controlled environment, allowing a maximum of 100,000 particles per cubic meter at sizes of 0.1 microns or larger.
Industries such as pharmaceutical manufacturing, biotechnology research, electronics manufacturing (particularly semiconductor fabrication), and certain medical device production heavily rely on ISO Class 5 cleanrooms. These environments ensure that critical processes remain free from contaminants that could compromise the integrity or functionality of products.
Despite not being as sterile as cleaner classifications such as ISO Class 1 to 4, ISO Class 5 cleanrooms still provide a highly controlled environment essential for upholding product quality and meeting stringent industry standards. Their role in ensuring controlled manufacturing processes underscores their significance in industries reliant on precise and contamination-free environments.
ISO 6 Cleanroom
An ISO Class 6 cleanroom is a controlled environment designed to maintain a moderate level of cleanliness, allowing a maximum of 1,000,000 particles per cubic meter at sizes of 0.1 microns or larger.
These cleanrooms, while less stringent in particle control compared to higher classifications, are essential in industries where controlled environments are necessary but with slightly higher particle tolerance.
Industries such as food processing, certain laboratory settings, and specific manufacturing processes benefit from ISO Class 6 cleanrooms. These environments ensure that processes remain within controlled parameters, minimizing contamination to acceptable levels.
ISO 7 Cleanroom
An ISO Class 7 cleanroom is designed to maintain a controlled level of cleanliness, allowing a maximum of 10,000,000 particles per cubic meter at sizes of 0.5 microns or larger.
These cleanrooms offer a moderately controlled environment suitable for industries where precision isn’t as critical but still requires controlled conditions to minimize contamination.
Industries such as non-critical manufacturing, certain laboratory processes, and specialized production benefit from ISO Class 7 cleanrooms. While not as stringent as cleaner classifications, these environments ensure that processes remain within acceptable contamination limits.
ISO 8 Cleanroom
An ISO Class 8 cleanroom maintains a controlled level of cleanliness at a maximum of 35,200,000 particles per cubic meter at sizes of 0.5 microns or larger. These cleanrooms offer a moderately controlled environment suitable for industries where less stringent cleanliness standards are acceptable.
Industries such as certain manufacturing processes, general production facilities, and some laboratory settings benefit from ISO Class 8 cleanrooms. While not as strictly controlled as cleaner classifications, these environments still aim to minimize contamination within defined limits.
ISO 9 Cleanroom
An ISO Class 9 cleanroom is the least controlled environment among the ISO cleanroom classifications.
This cleanroom allows a maximum of 352,000,000 particles per cubic meter at sizes of 0.5 microns or larger, providing a basic level of controlled conditions suitable for some general industries where minimal cleanliness standards suffice.
Industries such as certain standard manufacturing processes, general assembly lines, and typical office settings might benefit from ISO Class 9 cleanrooms. These environments aim to minimize contamination to a degree within the established limits.
Cleanroom Features by ISO Class
| ISO Class | Air Change Rate (per hour) | Typical Airflow Type | Personnel Gowning Requirements |
|---|---|---|---|
| ISO 1 | 500–750+ | Unidirectional (Laminar) | Full suit, goggles, gloves, respirator |
| ISO 2 | 480–720 | Unidirectional | Full suit, goggles, gloves |
| ISO 3 | 400–600 | Mostly unidirectional | Full gowning, hair cover, gloves |
| ISO 4 | 300–450 | Mixed airflow | Full gowning with coverall and gloves |
| ISO 5 | 240–360 | Mixed with laminar zones | Gown, face mask, hair net, gloves |
| ISO 6 | 90–180 | Non-unidirectional | Hair net, lab coat, gloves |
| ISO 7 | 60–120 | Non-unidirectional | Smock, shoe covers, hair cover |
| ISO 8 | 10–25 | Non-unidirectional | Minimal: hair net, basic lab attire |
| ISO 9 | <5 | Standard HVAC | No special gowning |
Other Types of Cleanrooms
Modular Cleanrooms
Modular cleanrooms are prefabricated, self-contained units that offer flexibility and speed of deployment. They can be installed quickly and are ideal for companies with evolving or temporary cleanroom needs. These structures are easy to expand, relocate, or reconfigure, making them a cost-effective solution for growing operations.
Hardwall vs. Softwall Cleanrooms
Hardwall Cleanrooms use rigid wall panels (such as aluminum, acrylic, or stainless steel) to create a sealed, durable environment. They provide superior environmental control and are suitable for high-precision or regulated industries.
Softwall Cleanrooms feature flexible plastic curtains suspended from a frame. They are more economical and quicker to set up, making them a popular choice for less demanding applications or for temporary projects.
Dry Rooms and Humidity-Controlled Cleanrooms
Certain processes—such as lithium battery production, OLED manufacturing, and pharmaceutical powder handling—require not only particle control but also strict humidity regulation. Dry rooms maintain ultra-low humidity levels, often below 1% relative humidity, to prevent moisture-related defects. These cleanrooms rely on specialized HVAC systems and dehumidifiers to maintain optimal conditions.
Clean Zones or Mini-Environments
Clean zones or mini-environments are localized, controlled spaces within a larger, non-controlled area. These compact cleanrooms are often used over conveyor lines, robotic workstations, or specific equipment in electronics manufacturing. They offer targeted contamination control without the cost of converting an entire facility into a cleanroom.
ISO vs. Other Cleanroom Standards
While the ISO 14644-1 standard is the most widely adopted framework for classifying cleanrooms globally, it is not the only standard in use. Other organizations, such as the U.S. Federal Standard 209E and the EU GMP (Good Manufacturing Practice) guidelines, have also played a significant role in defining cleanroom requirements, particularly in specific industries or regions.
ISO 14644-1
- Global applicability: Recognized internationally and applicable across industries.
- Classification basis: Focuses on particle concentration per cubic meter of air at defined particle sizes.
- Classes: Ranges from ISO 1 (most clean) to ISO 9 (least clean).
- Use case: Widely used in electronics, aerospace, biotech, and pharmaceuticals.
Federal Standard 209E (FED-STD-209E)
- Region: Primarily used in the U.S. before being officially canceled in 2001.
- Classification: Based on particles per cubic foot, not cubic meter.
- Legacy terminology: Cleanrooms were classified as Class 1, 10, 100, 1,000, etc., which still appear in some U.S. documentation.
- ISO comparison: For example, FS209E Class 100 roughly corresponds to ISO Class 5.
| FED-STD-209E Class | >0.1 µm | >0.2 µm | >0.3 µm | >0.5 µm | >5 µm | ISO Equivalent |
|---|---|---|---|---|---|---|
| 1 | 35 | 7 | 3 | 1 | ISO 3 | |
| 10 | 350 | 75 | 30 | 10 | ISO 4 | |
| 100 | 100 | ISO 5 | ||||
| 1,000 | 1,000 | 7 | ISO 6 | |||
| 10,000 | 10,000 | 70 | ISO 7 | |||
| 100,000 | 100,000 | 700 | ISO 8 |
EU GMP Guidelines (Annex 1)
- Industry: Specific to pharmaceutical and sterile medicinal product manufacturing.
- Focus: Includes both airborne particle concentration and microbiological limits.
- Grades: Classifies clean areas as Grades A through D.
- ISO relation: EU GMP Grade A typically aligns with ISO Class 5 in terms of particle count, but adds microbiological requirements.
| Grade | At Rest >0.5µm/m³ | At Rest >5µm/m³ | Operational >0.5µm/m³ | Operational >5µm/m³ | ISO Equivalent (Rest/Operational) | FED-STD-209E Equivalent (Rest/Operational) |
|---|---|---|---|---|---|---|
| A | 3,520 | 20 | 3,520 | 20 | ISO 5 / ISO 5 | Class 100 / Class 100 |
| B | 3,520 | 29 | 352,000 | 2,900 | ISO 5 / ISO 7 | Class 100 / Class 10,000 |
| C | 352,000 | 2,900 | 3,520,000 | 29,000 | ISO 7 / ISO 8 | Class 10,000 / Class 100,000 |
| D | 3,520,000 | 29,000 | Not Defined | Not Defined | ISO 8 / — | Class 100,000 / — |
Choosing the Right Cleanroom Class
Selecting the right cleanroom class is crucial for industries where contamination control is essential. The choice depends on:
- Industry Requirements: Different industries have varying contamination tolerance levels. For example, semiconductor manufacturing requires ISO Class 1 or 2, while food processing may only require ISO Class 6.
- Process Sensitivity: Processes that involve very fine or delicate materials, like nanotechnology or pharmaceuticals, require stricter cleanroom standards.
- Regulatory Compliance: Different industries are subject to specific regulatory standards that dictate the cleanroom class required. Pharmaceutical companies, for instance, must comply with Good Manufacturing Practices (GMP), which may require ISO Class 5 or higher.
- Cost Considerations: Higher class cleanrooms are more expensive to maintain due to stricter controls. Therefore, businesses must balance the necessary cleanliness with budget constraints.
Final Thoughts
Taking a closer look at ISO cleanroom classifications really highlights how important they are in keeping things clean and controlled across different industries. From high-tech fields like semiconductor manufacturing to pharmaceuticals, these cleanrooms make sure that everything stays in tip-top shape.
Whether it’s the ultra-sterile environment of ISO Class 1 or the more laid-back setting of ISO Class 9, each cleanroom serves a specific purpose and ensures products stay safe, high-quality, and up to industry standards.
At the end of the day, knowing which cleanroom class to use can make all the difference. It’s not just about cleanliness, but about protecting sensitive processes and ensuring that every product meets the right safety and quality requirements.
So, no matter where cleanrooms are in action, whether it’s nanotech or biotechnology, they play a crucial role in maintaining product integrity and supporting innovation in a variety of industries.