Everything you need to know about cleanroom standards

Cleanrooms are special rooms or indoor environments where the number of particles and contaminants in the air, the temperature, humidity and pressure are all prescribed by strict standards, including the number of micron and tenthmicron particles. Cleanrooms are meant for controlling and maintaining the number of these particles on the same level.

Cleanrooms are used widely across several industries such as fine mechanics, pharmaceuticals, automotive and space technology. More and more industries have been discovering the benefits of using cleanrooms in their production. All these industries require a highly controlled environment provided by high-quality equipment.

Why control the air?

The reason is different in each industry. Mostly, the goal is to create products that are completely protected from airborne contamination. For example, no one wants to see a small particle or dust behind the display of a new phone. There are many other reasons apart from this, why cleanrooms should be used in manufacturing. For the pharmaceutical and microbiology industries, it is critical to maintain sterility and extreme hygiene, while in laboratories, the main goal is to keep the samples protected from the lab environment.

Cleanroom Standards


The oldest, US FED STD 209E standard is no longer valid. However, several multinational companies still determine their requirements based on FED209E standards to this day.

Classmaximum particles/ft3ISO equivalent
≥ 0,1 µm≥ 0,2 µm≥ 0,3 µm≥ 0,5 µm≥ 5 µm
1357,5310,007ISO 3
103507530100,07ISO 4
1003 5007503001000,7ISO 5
1 00035 0007 5003 0001 0007ISO 6
10 000350 00075 00030 00010 00070ISO 7
100 0003.5×106750 000300 000100 000830ISO 8

ISO 14644-1

ISO14644-1 is the most widespread modern cleanroom standard that not only defines the design of clean rooms, but also provides guidelines for implementation and use. Many manufacturers base their requirement system on ISO-14644:

Classmaximum particles/m3 aFED STD 209E equivalent
≥ 0,1 µm≥ 0,2 µm≥ 0,3 µm≥ 0,5 µm≥ 1 µm≥ 5 µm
ISO 110bdddde
ISO 210024b10bdde
ISO 31 00023710235bde1
ISO 410 0002 3701 02035283be10
ISO 5100 00023 70010 2003 520832d,e,f100
ISO 61 000 000237 000102 00035 2008 3202931 000
ISO 7ccc352 00083 2002 93010 000
ISO 8ccc3 520 000832 00029 300100 000
ISO 9ccc35 200 0008 320 000293 000Room air

a The following concentrations are cumulative measures, i.e. maximum permissible levels in a certain category refer to all particles of a given size or smaller.

b When testing these values, a large volume of air is required for sampling, which the standard makes specific recommendations for.

c This value is not specified by a certain class, since the limit would not be significant because of the very high concentration values.

d Measuring such small concentrations is not practical due to technical difficulties, therefore, these values are not specified by the standard.

e Measuring the low concentration of particles larger than 1 μm is problematic because the meter itself absorbs a fraction of the particle, which is difficult to control. Thus, these values are not specified.


The GMP guidelines may be the strictest standards for cleanrooms, as they require an in-service qualification process, i.e. the cleanroom is tested during normal operations.

Classmaximum particles/m3
At RestIn Operation
≥ 0,5 µm≥ 5 µm≥ 0,5 µm≥ 5 µm
Grade A3 520203 52020
Grade B3 52029352 0002 900
Grade C352 0002 9003 520 00029 000
Grade D3 520 00029 000Not definedNot defined

Nevertheless, cleanroom standards do not only include requirements referring to the number of particles in the controlled environment. Well-designed cleanrooms take into account the number of air exchanges required to stay within the boundaries, the required inflow and suction points, their positioning and coverage of the ceiling, and the direction of air flows.

Cleanroom standards therefore include complex technology guidelines that help you to create an environment with appropriate equipment that matches the specificities of your industry.

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