Cleanroom 101: Definition, History, Uses and ISO Cleanroom Requirements

A cleanroom is a highly controlled environment with low levels of pollutants such as airborne microbes, aerosol particles, chemical vapors, and dust. Cleanrooms are commonly used in manufacturing, scientific research, aerospace, electronics, and other industries whose manufacturing process may be affected by particles or other contaminants.

To be considered a cleanroom, the area must have a controlled contamination level, which is specified by the number of particles per cubic meter.

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What is a Clean Room Environment?

A cleanroom is any controlled area where contaminants and airborne particles are highly controlled and kept within strict limits. They are used in different industries, including aerospace, healthcare, life sciences, electronics, biotech, optics, military, and other branches where substantial amounts of particles could affect manufacturing.

The High-Efficiency Particulate Air (HEPA) filter is the key component of any cleanroom. Its role is to trap all the particles larger than 0.3 microns, which represent one of the most penetrating particle sizes. According to scientists, 0.3 micron-particles tend to evade air filters more than any larger or smaller particles.

The air inside a cleanroom goes through the HEPA filter, capable of trapping even 99.97% of 0.3-micron particles. Modern HEPA filters have interlaced glass fibers twisted and turned in multiple directions to form a fibrous maze. When particles enter this web, they leave it in some of the following ways:

  • Direct impaction: Dust, mold, pollen, and other types of large contaminants tend to travel in a straight path.
  • Sieving direction: Sieving happens when the particle is too large to fit between the fiber spaces.
  • Interception: Direct interception occurs when the particles are not large enough to have inertia or small enough to diffuse within the flow.
  • Diffusion: Diffusion works on the tiniest particles. Since the air cannot hold small particles in place, they tend to diffuse within the flow stream.

While HEPA filter purifies the air quite efficiently, some cases may require Ultra Low Particulate Air (ULPA) filters. These provide next-level cleanliness in situations where it is needed

Cleanroom Fun Facts

Although the idea of cleanroom might not sound exciting at first, you’ll change your opinion once you’ve read the following cleanroom facts:

  • A person standing in a cleanroom emits more than 100,000 particles per minute. To avoid potential cross-contamination, cleanroom staff must wear special garments that prevent the release of particles.
  • NASA uses cleanrooms regularly to foster their space program growth, including the airflow technology and airflow development.
  • Food industries use cleanrooms. More and more food industries rely on cleanrooms to manufacture products according to high sanitation standards.
  • Many different types of contamination can affect the production quality. Substantial amounts of contaminants, microorganisms, and air particles may lead to product failure. Certain cleanroom supplies, such as solutions, wipes, and swabs, can reduce contamination levels.

A Brief History of Cleanrooms

Do you know when the idea of cleanroom first started and what was its initial goal?

The first cleanroom dates back to the mid-19th century, where cleanroom environments were used in hospital operating rooms. However, the first modern cleanrooms were formed during WWII and were used to manufacture military weaponry in a safe and sterile environment. As for the HEPA filters, it is known that they were being utilized in cleanrooms by the early 1950s.

Although there are various theories regarding when and how the first cleanroom was established, it is important to remember that they appeared as an innovative solution for a severe problem – contamination.

The idea of a cleanroom has significantly evolved since its beginnings. Today, it varies in size, can have portable cleanroom design, and is used by various industries, including scientific research, software engineering, manufacturing, and more.

Cleanroom Classifications and ISO Cleanroom Standards

Cleanroom classifications refer to how clean the air is. The Federal Standard 209 of the USA states that the number of particles that equals to or is greater than 0.5 microns in one cubic foot of air is the count used to classify the cleanroom.

Cleanrooms are classified based on the numbers and size of contaminants permitted per air volume. That said, you may notice “class 10,000 clean rooms” or “class 100 clean rooms.” These signs indicate the number of 0.5micron-sized particles, or larger, allowed per cubic foot of air.

The ISO 14644-1 classification system is the primary authority in the US and Canada. It includes the following cleanroom classes: ISO 1, ISO 2, ISO 3, ISO 4, ISO 5, ISO 6, ISO 7, ISO 8, and ISO 9. While ISO 1 is considered the cleanest class, ISO 9 stands for the “dirtiest” area. However, it is still much cleaner than a regular room.

Let’s take a look at the ISO cleanroom requirements table:

Class Maximum  Particles/m³ FED STD 209E equivalent
>0.1 um >0.2 um >0.3 um >0.5 um >1 um >5 um
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 Class 10
ISO 5 100,000 23,7000 102,000 3,520 8,320  293 Class 100
ISO 6 1,000,000 237,000 102,000 35,200 8,320 2,930 Class 1,000
ISO 7 352,000 83,200 2,930 Class 10,000
ISO 8 3,520,000 832,000 29,300 Class 100,000
ISO 9 35,200,000 8,320,000 293,000 Room Air

The most common clean room classes include ISO 5, ISO 6, ISO 7, and ISO 8.

ISO 5 Cleanroom Requirements

ISO 5 is considered a super clean cleanroom classification. ISO 5 cleanroom requirements state that the area must have less than 3,520 particles >0.5 microns per cubic meter, as well as 250-300 HEPA filtered air changes per hour. ISO 5 cleanrooms are commonly used in semiconductor manufacturing and for pharmaceutical purposes. Pristine Clean Bags® are manufactured in an ISO 5 class cleanroom in order to provide our customer’s with the highest level of cleanliness.

ISO 6 Cleanroom Requirements

ISO 6 is a very clean cleanroom. According to the ISO Class 6 cleanroom requirements, a cleanroom must have less than 35,200 particles >0.5 micron per cubic meter and 180 HEPA filtered air changes per hour. It is commonly used in biotechnology, nanotechnology, and different cleantech manufacturing applications, including solar, film/packaging, medical device, etc.

ISO 7 Cleanroom Requirements

ISO 7 is a common clean cleanroom class. ISO 7 cleanroom requirements indicate that a cleanroom must have less than 352,000 >0.5 micron per cubic meter and 60 HEPA filtered air changes per hour. The most common ISO 7 cleanroom applications are pharmaceutical, electronic, and medical device manufacturing.

ISO 8 Cleanroom Requirements

ISO 8 is the least clean cleanroom class. According to the ISO Class 8 cleanroom requirements, the area mustn’t have more than 35,200,200 particles >0.5 microns per cubic meter. It should have 20 HEPA filtered air changes per hour. The most common uses include e-liquid manufacturing, nutraceutical packaging, and plastic extrusion for medical devices.

ISO Class Average number of air changes per hour
ISO 5 240–360 (unidirectional air flow)
ISO 6 90–180
ISO 6 30–60
ISO 8 10–25
Conventional building 24

Cleanroom Personnel and Clothing

People who work in cleanrooms must undergo comprehensive training for contamination control theory. They enter and leave cleanrooms through airlocks, air showers, or gowning rooms wearing special clothing that traps contaminants naturally produced by the human body.

Clean room clothing is specifically designed to stop substances from being released from the person’s body and potentially contaminating the environment. Wearing cleanroom garments is of vital importance because the personnel’s contamination can significantly affect the product manufacturing process or lead to cross-contamination between medical staff and the patients.

The exact cleanroom garment choice depends on the product specifications and cleanroom class, about which we’ll talk later. However, one cannot enter the cleanroom without wearing a proper cleanroom suit, which may consist of the following:

  • Aprons
  • Beard covers
  • Boots
  • Bouffant caps
  • Face masks
  • Gloves
  • Gowns
  • Hairnets
  • Hoods
  • Lab coats
  • Shoe covers
  • Shoes

While some low-level cleanrooms may require only simple headcovers and booties, others include careful and thorough gown-wearing procedures, zipped coverall, and gloves.

Industries That Use Cleanrooms

The manufacturing of certain products requires a clean and sanitized space to ensure no harmful particles could affect the product quality. More and more industries use cleanrooms, and depending on what they produce, they need a distinct ISO class for the room. Let’s remember that ISO Class 1 cleanrooms are the cleanest, while ISO Class 9 has the lowest standards.

Let’s see what industries commonly use cleanrooms for their production:

Computer & Electronic Part Manufacturing

External factors, such as temperature and humidity, can cause a lot of damage to the computer and electronic parts. Cleanrooms used in this industry rely on different cleanroom products, including anti-static coveralls, lab coats, electrostatic discharge cleaning products (ESD), anti-static wipes, and more. Electronic manufacturing cleanrooms often require an ISO Class varying from Class 1 to 6.

Biotech Industry

The biotechnology industry encompasses various markets, including medical research, agricultural research, industrial research, and environmental research. Since these fields deal with the sensitive matter and live cells, the space where they operate must be contaminate-free.

Biotechnology industries entail aprons, swabs, wipes, gloves, face masks, and more. Cleanrooms necessary for their research must be ISO 5 or ISO 8 classified.

Life Sciences

Life sciences refer to chemistry and medical biology focused on the animal, plant, or human cells. Life science industries manipulate cells within fluid and organic matter. As you can guess, these are very sensitive to any type of contamination.

Cleanrooms in the life science field must use presaturated and dry wipes, disinfectants, swaps, sterile products, and mops. Life science industries often require an ISO 5 or 8 clean rooms class.

Food Manufacturing Industries

Food manufacturing industries have recently started to use cleanrooms, and they did it to prevent the contamination of processed foods. Food production and manufacturing require cleanrooms with high hygiene standards to prevent the development and growth of mold, bacteria, or fungi.

To create a perfect environment for food manufacturing, it is essential to regulate humidity, temperature, air velocity, air pressure, and moisture levels. Cleanrooms in these industries require wearing face masks, gloves, safety glasses, shoe covers, and other essential cleanroom apparel that prevent the spread of particles.

The ISO clean room levels for food manufacturing may vary because foods may have varying sensitivity levels. Still, it must meet the ISO 6 requirements.

Automotive Industry

Modern vehicles have a wide variety of sensitive computer components and electronic parts that can be affected and damaged by excess moisture, temperature, static, and air pressure. Therefore, automotive industry cleanrooms must have anti-static coveralls, lab coats, wipes, and specific cleaning products.

The ISO standards automotive cleanrooms must meet depends on the parts that are being manufactured. Generally, they entail ISO Classes between 6 and 8.

Aerospace Industry

The aerospace industry requires highly controlled environments to perform experiments, produce space-flight lasers, and create other state-of-the-art aerospace tools seeking optimum accuracy.

The aerospace industry requires cleanroom ISO classes 1- 8 depending on the sensitivity of the components.

Optical Industry

Lenses on professional cameras must be produced within a cleanroom. When it comes to lens manufacturing, specific protocols must be followed, including particle contamination controls, humidity and temperature regulation, and vibration isolation. That way, we can use our cameras to capture unforgettable moments.

The lens manufacturing must meet the ISO Class 7 requirements.


The nanotech cleanroom is suitable for various industries and applications, including optics, medical devices, semiconductors, pharmaceutical delivery systems, etc. All these fields are characterized by extreme sensitivity to particles and contaminants, which is why they require exceptionally clean environments.

Nanotechnology cleanrooms are typically ISO Class 4-9 classified.

Most Popular Clean Room Design & Types

It is believed that cleanrooms are among the most complicated areas to design, mainly because the process involves the management and regulation of humidity, temperature, pressure, and static.

Since cleanrooms are used in different industries, their design may vary. That said, each cleanroom design comes with unique features suitable for various purposes. The most popular cleanroom designs are:

Stick-Built Cleanrooms

The stick-built cleanrooms feature metal-framed construction. It is a traditional cleanroom design constructed from individual parts onsite, and it is a less common choice among cleanroom seekers.

Still, stick-built cleanrooms are a more affordable solution due to lower material costs and the simplicity of techniques used for their creation.

Modular Cleanrooms

Modular cleanroom construction consists of the walls and ceiling panels that are manufactured in a factory, delivered to the desired place, and assembled on site. The materials used in modular cleanroom manufacturing are non-shedding, non-absorptive, and non-reactive, ensuring the safety, strength, and quality of the product manufactured within its space. One of the greatest advantages of modular cleanrooms is their portable design.

The most common types of modular cleanrooms are:

Hardwall Cleanrooms

Hardwall modular cleanrooms are designed to comply with even the strictest cleanroom classifications (ISO Class 1, for example). A blend of a coated aluminum frame and a prefabricated panel ensures hardwall cleanrooms can create an environment where static, humidity, pressure, and contamination are highly controlled.

A hardwall cleanroom can be installed within an existing structure and modified in case your classification requires higher contaminant protection. These cleanrooms are suitable for a myriad of applications, including medical research, pharmaceuticals, aerospace, semiconductor industries, or sensitive electronics manufacturing.

Hardwall cleanrooms are incredibly durable and can be reused, repurposed, or relocated without affecting their quality.

Softwall Cleanrooms

A minimalist and lightweight cleanroom that complies with most classification standards is a softwall cleanroom. It is highly customizable and has different filtration options and other useful modifications.

Softwall cleanrooms feature a compact cleanroom design, which is why they can work anywhere within your facility or another cleanroom. They are affordable, easy to assemble and maintain, and incredibly suitable for plastics manufacturing, growrooms, and automotive industries.

While they can accommodate most cleanroom classifications, softwall cleanrooms are ideal for ISO Classes 4 to 8.

Rigidwall Cleanrooms

Rigidwall cleanrooms are convenient for cleanrooms with ISO Class 5-8 classifications. Their wall panels are transparent, providing the area with a pretty attractive, sleek, and minimalist style.

Rigidwall cleanrooms are a popular choice for multiple applications in the automotive, aerospace, medical device packaging, and plastics manufacturing industries.

How to Choose a Suitable Cleanroom?

Planning a cleanroom is quite a comprehensive process during which you must pay attention to different things. For example:

1.      Consider the Cleanroom Requirements

It is essential to define your cleanroom requirements to ensure you’re getting what you need. This will depend on your industry and the number of particles permitted in the area where the product is being manufactured. Keep in mind that even the smallest particles may cause severe issues.

2.      Pick Adequate Ventilation System

The right ventilation system depends on the ISO class your cleanroom must comply with. The airflow plays a vital role in the cleanroom’s cleanliness level, and it should be created to prevent particle deposition at any critical points. Consider air conditioning units to regulate temperature and humidity in the cleanroom.

3.      Select the Right Material for Ceilings, Floors, and Walls

The materials for cleanroom ceilings, walls, and floors should be easy to clean and resistant to the chemicals cleaning agents contain.

Cleanroom cleaning is another critical thing to consider because it must be performed by specialists. Ensure you’re planning the cleaning and maintenance cycles in advance according to your cleanroom classification and requirements.

4.      Pay Attention to the Furniture Inside the Cleanroom

As a general rule of thumb, the surfaces for seating you keep in the cleanroom should be abrasion-resistant and mustn’t be made of fabrics. As for tables, and storage furniture, consider stainless steel, melamine coating, or various types of plastics.

5.      Don’t Forget the Right Protective Clothing for Your Staff

People naturally carry a significant amount of contaminants, which is why it’s important to wear protective clothing while in the cleanroom. The exact cleanroom garments the staff will have to wear depends on the cleanroom classifications. For instance, ISO 6 classification requires a face mask, a full-body overall, special shoes and gloves, safety goggles, etc.


frequently asked question

In What Situations Is the Cleanroom Required?

A cleanroom is required by industries whose product manufacturing requires safe and sterile environments. These areas provide a clean space, reducing the number of contaminants that could affect products such as computer chips, pharmaceuticals, etc.
frequently asked question

What is Cleanroom Testing?

Cleanroom testing is a process that proves that a system produces a product according to all the standards and specifications. Each cleanroom must meet a class standard set by the National Environmental Balancing Bureau (NEBB) in order to be qualified for use.

Additionally, FDA validation is required for the biopharmaceutical, pharmaceutical, medical, and food manufacturing industries.

frequently asked question

What We Should and Shouldn’t Do in a Cleanroom?

It is important to know that the following actions are strictly forbidden in a cleanroom:

• Eat or drink
• Bringing dirty equipment
• Turning off the HEPA filter.

On the other hand, you are encouraged to do the following:

• Wipe down the surfaces regularly to eliminate contamination
• Close all the doors to maintain positive pressure
• Ensure your staff is wearing protective cleanroom suits.

frequently asked question

What Materials are Allowed in a Cleanroom?

The materials allowed in a cleanroom depend on its specific requirements. However, most cleanroom-safe items include the following:

• Paper, notebooks, pens, and pencils
• Tape or adhesives
• Solvents
• Plastic containers
• Cleaning materials (mops, buckets, wipes, detergents, and more).

Still, it is prohibited to bring the following objects:

• Food, drink, gum
• Jewelry and makeup
• Wood and leather products
• Oils, greases, and lubricants
• Velcro
• Powders
• Unapproved tape, adhesive, or plastics.

frequently asked question

Are There Some Tips and Tricks to Decrease Contaminant Levels in a Cleanroom?

Since people create more particles than anything else within a clean room, we can do something to decrease contaminant levels. For example:

• Make slow, calm movements
• Keep talking to a minimum
• Avoid entering the cleanroom right after smoking
• Wash hands before and after entering the clean area
• Put clothes on and take them off correctly
• Use hairnets or and beard covers
• Do not bring unnecessary equipment into a clean room.

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