Clean rooms are widely understood as engineered spaces within facilities that have stringent levels of sterilization and air purification. But what actually defines a clean room? Clean rooms are a general term for what are actually a series of room types with meaningful differences in the level of service provided, and what constitutes a “clean room” will vary significantly by industry or application. What is considered clean room for a less stringent industry may be wholly inadequate for precision applications like nanotechnology. Definitions of clean rooms can also raise issues when supplier agreements or legislative requirements expect a certain level of cleanliness, or when trying to validate the claims or guarantees of a technology or a clean room service. It is for this reason that clean room classifications and classification charts are an important industry source of standardization.
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Industry Standard Clean Room Classification
Aeroex is fully aligned with the international best practices for clean room classification. ISO 14644 provides a series of standards for clean room classification and cleanliness. There are fourteen documents within the series that cover topics including design, microbial air concentrations, testing methods, particle sizes concentrations, and air cleanliness. Notably, ISO 14644-1 provides clean room classifications by air cleanliness. Aeroex uses ISO 14644-1 when designing clean room air purification systems like the Air-Fit or when working with clients on a deployment plan for their target level of clean room classification. See below for Aeroex’s industry-standard clean room classification chart: 
How to Read and Use the Clean Room Classification
The clean room classification chart provides 9 classes of clean rooms. These are itemized down the side as ISO-1 to ISO-9, the definitions provided by ISO 14644. Here, ISO-9 is the “dirtiest” and ISO-1 is the “cleanest”.
Across the top are a series of particle size concentrations, measured in microns (depicted as μm). A micron is a particle 1×10−6 meters in length. Particle sizes considered by ISO 14644 range from 0.1 to 5.0 μm, meaning these particles are very small. This is why Aeroex air purification systems like the Air Fit use HEPA filters capable of removing 99.99% of particles as small as 0.3 μm. These particle size concentrations list the maximum allowable number of particles of the given size category within a cubic meter of air in a clean room.
To read the table, start with your required ISO classification target, and read across. In each column with a value, the number listed in the cell corresponds to the total number of particles of that micron/sub-micron size within a cubic meter of the room. Note that each clean room classification allows a few similar particle size categories, which is reflective of most size distributions for contaminants. These values should be used as the basis for your targets in designing your clean room, selecting your air purification technology, or monitoring your air quality for ISO compliance.
There are a number of ways to use the clean room classification chart depending on your progress with implementing your clean room. You may be in the very early stages of designing your clean room and may wish to study the different levels from ISO-1 to ISO-9 used in industries you could support as clients. Or, a regulatory requirement in your industry may be informing your target. Even after your clean room is designed, operators continue to reference the chart when monitoring their performance.
Transitioning from FED STD 209E
FED STD 209E is the American precursor to ISO 14644. Titled Airborne Particulate Cleanliness Classes in Cleanrooms and Cleanzones, 209E was superseded by the new international standard. Some legacy applications still work with 209E, and Aeroex is comfortable working with both classification charts interchangeably as needed. The corresponding 209E equivalent is provided in our chart for reference.
Why are Clean Room Classifications Important?
Understanding the various contaminant limits for different levels of clean rooms or different jurisdictions are important to help manage your business and maintain your facility. By knowing how to navigate the various standards, you can keep your business resilient and positioned to get new opportunities. Consider the following reasons:
- It’s the Law. In regulated jurisdictions like pharmaceutical manufacturing, government agencies set specific standards for sterilization and air purification that need to be followed. Knowing what designation from the chart is expected will inform the clean room air purification system you require along with other design features.
- ISO Certification and Business Reputation. When you establish a clean room for a given cleanliness standard, you can request an evaluation to receive ISO certification. By obtaining the ISO certification, your business will rise in reputation for having an internationally trusted endorsement of the level of service you provide.
- Adaptable to Changes in Standards. With increasing evidence of the benefits of workplace safety, sterilized conditions, etc., what is considered the “minimum” requirement for microbial limits may not be the same tomorrow or in the future. Working to exceed the limits or knowing the thresholds can “future proof” your business by preparing you in advance for any regulatory or supplier changes.
- Secure Your Clients. Many jurisdictions are not legally regulated to establish clean room conditions but their business cannot function without one! This is notable in industries like nanotechnology and optical manufacturing. Establishing and monitoring a clean room with a concentration limit from the chart will help to secure your clients or achieve the conditions of any supplier agreements.
- Support Emerging Technologies and Industry. There are emerging business cases for new applications of clean rooms, such as during the production of solar panel components where impurities can lead to inefficient energy conversion. Monitoring the industries and being prepared to meet their required microbial limits can help you win new business.
Find More Clean Room Resources
Aeroex is committed to the advancement of the clean room industry and providing our clients with the best advice. Our products are designed by engineers and manufactured in Canada. Visit our website to find other resources similar to the classification chart and contact Aeroex today to get expert advice firsthand.
