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Clean room by Allied Cleanrooms - USP 797, and ISO 4, ISO 5, ISO 6, ISO 7, and IS0 8, cGMP cleanroom manufacturing, soft wall cleanrooms FED-STD-209E and ISO 14644-1, control contamination

ISO 8 Cleanrooms: Definition and Requirements

In research and manufacturing, it is sometimes necessary to control environmental conditions, such as temperature, humidity, or even airborne particle counts. By doing this, organizations can avoid issues with sensitive processes and products. Cleanrooms, which regulate airborne particles, are one such type of controlled environment. In this article, we’ll focus specifically on ISO Class 8 cleanrooms, explaining what they are, their requirements, applications, and more.

What is an ISO 8 Cleanroom?

An ISO Class 8 cleanroom is defined by the International Organization for Standardization (ISO) 14644-1 standards. ISO cleanroom standards set limits on the size and number of airborne particles allowed in cleanrooms.

These cleanrooms allow a maximum particle count for the following:

  • 3,520,000 particles for sizes 0.5 micrometers or larger.
  • 832,000 particles for sizes 1 micrometer or larger.
  • 29,300 particles for sizes 5 micrometers or larger.

From the above, you might have noticed that there are only three categories of particle sizes. This is because ISO 7, ISO 8, and ISO 9 cleanrooms only measure three sizes. The other ISO classifications measure either more sizes or entirely different sizes. We can see below how ISO Class 8 cleanrooms compare to the other classifications.

A cleanroom ISO classifications chart, with ISO 8 highlighted.
ISO 14644-1 cleanroom classifications with the ISO 8 classification highlighted.

How Particle Counts Work in ISO Class 8 Cleanrooms

To understand how particle counts work, it’s important to keep in mind that the maximum particle counts in cleanrooms are cumulative. This means that each particle can be counted in multiple categories based on its size. Here’s a couple of examples of how it works:

  1. If a particle is 2 micrometers in size, it is included in the count for all particles larger than 1 micrometer, and also in the counts for every size category smaller than 2 micrometers.
  2. Similarly, a particle that is 5 micrometers in size is counted not only in the category for particles over 5 micrometers but also in every smaller particle size category, down to the smallest measured.

In short, a single particle is often counted multiple times, once in each size category that it meets or exceeds.

Is an ISO Class 8 Cleanroom the Same as a Class 100,000 Cleanroom?

ISO Class 8 cleanrooms are the same as Class 100,000 cleanrooms. The previously used Federal Standard 209E (FED-STD-209E) categorized Class 100,000 cleanrooms based on the number of particles per cubic foot, using the imperial system rather than the metric system.

Specifically, Class 100,000 cleanrooms permitted a maximum of 100,000 particles larger than 0.5 micrometers per cubic foot of air, which explains the “100,000” in Class 100,000.

The current ISO 14644-1 standard measures particles per cubic meter. Despite this, “ISO 8” and “Class 100,000” continue to be used interchangeably by some in the industry.

US Federal Standard 209E for cleanrooms.
US Federal Standard 209E for cleanrooms.

ISO 8 Cleanroom Requirements

ISO Class 8 is one of the “dirtiest” cleanroom classifications, but these environments are still much cleaner than the average office space.

They still use some advanced features, though less than cleanrooms with a stricter cleanliness classification, such as ISO 7, 6, 5, and below.

Entry into an ISO Class 8 cleanroom does not require progression through cleaner spaces, as is usual for entering other higher-grade cleanrooms. However, implementing control measures to prevent contamination is still important.

Here are some of the basic requirements for these environments.


ISO Class 8 cleanrooms do not require unidirectional (laminar) airflow, which is a necessity for ISO 5 and stricter cleanrooms. Instead, they can operate with standard non-directional (turbulent) airflow systems. These systems are much cheaper, as maintaining unidirectional airflow can get expensive.

An air handling unit for a modular cleanroom.
An air handling unit for a modular cleanroom.

Similarly, they can be either hardwall or softwall. Softwall cleanrooms are much cheaper than hardwall cleanrooms, but they only allow one pass through of air. This means that softwall cleanrooms do not allow for complex HVAC systems. In stricter cleanrooms, you may need to have recirculating air to meet the proper standards, but in ISO 8 environments, one pass through is usually enough.

Clean room by Allied Cleanrooms - USP 797, and ISO 4, ISO 5, ISO 6, ISO 7, and IS0 8. Modular Cleanroom by allied cleanrooms Modular Cleanroom by allied cleanrooms Clean room by Allied Cleanrooms Supplier - USP 797, and ISO 4, ISO 5, ISO 6, ISO 7, and IS0 8, cGMP cleanroom manufacturing, soft wall cleanrooms FED-STD-209E and ISO 14644-1, control contamination
A softwall cleanroom.

Air Changes Per Hour

ISO Class 8 cleanrooms require around 20 air changes per hour (ACPH), which, while much less than the requirements for an ISO Class 5 cleanroom, still represents a high degree of fresh air, especially compared with a typical residential or office environment. For reference, a normal residential space might have one or two ACPH.

The high ACPH rate helps maintain the particle limits by continuously removing particles from the air.

Ceiling Coverage

The requirement for ceiling coverage in ISO 8 environments is less demanding compared to other cleanrooms. These cleanrooms typically require a ceiling coverage of about 15-25%. (This percentage refers to the portion of the ceiling equipped with filters through which clean air is circulated.)

Ductwork over the ceiling.
Some ductwork enters the ceiling of a cleanroom environment.


For ISO Class 8 cleanrooms, the use of high-efficiency particulate air (HEPA) filters is standard. These filters trap 99.97% of particles that are 0.3 micrometers or larger.

While HEPA filters are sufficient for most ISO 8 applications, the specific requirements for filtration can vary based on the processes being conducted within the cleanroom. The selection of HEPA or ULPA filters depends on the size of the particles that cause issues with products or processes.

Applications of ISO 8 Cleanrooms

Many industries use ISO Class 8 cleanrooms. They are typically used where some cleanliness is needed, but without the high cost and pristine conditions required by stricter ISO classifications. Here are some examples of industries that use them:

  • Aerospace: Cleanrooms ensure the integrity of materials used in aircraft and spacecraft.
  • Medical device manufacturing: Cleanrooms prevent any issues to the assembly of devices.
  • Food processing facilities: Cleanrooms maintain the cleanliness quality of food products.
  • Pharmaceutical packaging: Medications are packaged in sterile conditions.
  • 3D printing: Cleanrooms prevent contamination of printed components.

ISO Class 8 cleanrooms may also be used as a place to put on gowning or other apparel before entering a cleaner space.

A gowning room with a man standing by a locker.
A gowning room in an ISO 8 cleanroom.

Customizing Your ISO 8 Cleanroom

Designing an ISO Class 8 cleanroom is not a one-size-fits-all process. Each project is different, and may include unique operational requirements, spatial constraints, or industry-specific regulations. Other considerations include material selection, layout, and HVAC system design.

With over 30 years of experience, Allied Cleanrooms knows that every project is unique. If you’re planning a cleanroom and need advice, feel free to reach out and get a free custom quote today.

Testing and Certification

ISO Class 8 cleanrooms undergo a series of tests after their construction to verify compliance with ISO 14644-1 standards.

Annual testing is required to monitor:

  • Particle counts
  • Airflow volume
  • Air pressure differentials

If the cleanrooms are equipped with systems that frequently monitor particle levels, airflow, and pressure, then they do not have to be tested every year, so long as all metrics stay within standards.

A modular cleanroom.
A modular cleanroom designed by Allied Cleanrooms.

Why ISO 8 Cleanrooms Matter

ISO Class 8 cleanrooms are crucial in sectors like aerospace and 3D printing, and with the ongoing miniaturization of components and the evolution of technology, the demand for these controlled environments will continue to increase. The global cleanroom market, valued at $7.26 billion in 2024, is projected to reach $9.5 billion by 2028. Growing at 6% per year, cleanrooms will play a pivotal role in current and future production landscapes.

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