What is an ISO-7 Cleanroom Classification?

By Anthony Chien
President, American Cleanroom Systems ®
40+ years of cleanroom design and engineering experience
Last reviewed: June 2026

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cleanroom gowning room interior, gown rack, stainless steel bench, storage racks

Figure 1. ISO-7 electronics PCB manufacturing modular cleanroom

What is an ISO7 Cleanroom?

An ISO7 cleanroom is a controlled environment certified under ISO 14644-1 that allows a maximum of 352,000 particles (≥ 0.5 µm) per cubic meter of air (equivalent to the legacy FED-STD-209E Class 10,000 standard). It typically requires 180 air changes per hour using HEPA or ULPA filtration

Figure 2. ISO cleanroom class pyramid

    ISO 8 Cleanroom Attribute
    Requirement / Information


    Governing standard
    ISO 14644-1

    ISO classification
    ISO Class 8

    ≥0.5 µm particles
    ≤3,520,000 particles/m³

    ≥1.0 µm particles
    ≤832,000 particles/m³

    ≥5.0 µm particles
    ≤29,300 particles/m³

    Former equivalent
    FED-STD-209E Class 100,000

    Cleanliness basis
    Airborne particle concentration

    HEPA filtration
    Typically at least 60 air changes per hour

    Typical applications
    Precision manufacturing, plastic injection molding for medical devices, nutraceuticals, gown rooms, aerospace assembly, 3D printing, food processing, mask manufacturing, cleanroom hallways, and cleanroom material transfer rooms

    Common construction types
    Modular, stick-built, softwall

ISO 8 Cleanroom Attribute	Requirement / Information
Governing standard	ISO 14644-1
ISO classification	ISO Class 8
≥0.5 µm particles	≤3,520,000 particles/m³
≥1.0 µm particles	≤832,000 particles/m³
≥5.0 µm particles	≤29,300 particles/m³
Former equivalent	FED-STD-209E Class 100,000
Cleanliness basis	Airborne particle concentration
HEPA filtration	Typically at least 60 air changes per hour
Typical applications	Precision manufacturing, plastic injection molding for medical devices, nutraceuticals, gown rooms, aerospace assembly, 3D printing, food processing, mask manufacturing, cleanroom hallways, and cleanroom material transfer rooms
Common construction types	Modular, stick-built, softwall

Table 1: ISO7 class at a glance

ISO-7 cleanrooms are required to have 60 air changes per hour of HEPA filtered air and less than 2,930 particles/meter3 greater or equal to 5 microns. By comparison, a conditioned office space (non -cleanroom space) would have more than 100X as many particles per meter3. ISO-7 cleanroom classification also has requirements for >0.5 micron and >1 micron size particles (see table 1).

Clase	Máximo de Partículas/ft³						ISO Equivalente
Clase	>0.1 um	>0.2 um	>0.3 um	>0.5 um	>1 um	>5 um	ISO Equivalente
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	23,700	10,200	3,520	832	29	Class 100
ISO 6	1,000,000	237,000	102,000	35,200	8,320	293	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

Table 2. ISO Clasificaciones de Cuartos Limpios

There is a separate FED 209E cleanroom classification system that has been historically used in United States for industrial cleanrooms such as semiconductor cleanrooms and printed circuit board cleanrooms. The ISO cleanroom classification is on metric system (particles per meter3). The FED 209E cleanroom classification system is based on imperial system (particles per feet3). There are comparable ISO and FED 209E cleanroom classes for each level of cleanliness. An ISO-7 cleanroom classification corresponds to FED 209E class 10k cleanroom classification (see table 2).

US FED STD 209E Estándares de salas limpias | Clasificaciones de salas limpias

    Clase
    Maximum Particles/ft³
    ISO Equivalent

    >0.1 µm
    >0.2 µm
    >0.3 µm
    >0.5 µm
    >5 µm
    
    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

Clase	Maximum Particles/ft³	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

Table 3: FED STD 209E Cleanroom Classifications

Which industries use ISO7 cleanrooms

USP797/800 compounding pharmacy cleanroom
Medical device manufacturing cleanroom
Printed Circuit board manufacturing cleanroom
Pharmaceutical solution preparation cleanroom
Pharmaceutical cream and ointment manufacturing cleanroom
Pharmaceutical liquid manufacturing cleanroom
Sala blanca de extracción de CBD
Sala limpia láser
Precision manufacturing cleanroom
Aerospace composite repair cleanroom
Semiconductor test and packaging cleanroom
R&D cleanroom

stainless steel cleanroom table, solid polished table top

Figure 3. ISO-7 USP797/800 compounding pharmacy cleanroom

cleanroom interior, amber cleanroom lighting, chemical fume hood

Figure 4. ISO-7 semiconductor test cleanroom

Figure 5. Air Flow simulation for ISO-7 recirculating modular cleanroom

Filtration for ISO-7 classification cleanrooms

Filtration for ISO-7 cleanrooms are done with HEPA filters. The best modular cleanroom design uses a negative pressure plenum with HEPA fan filter units in the ceiling and incorporated low wall air returns to achieve laminar air flow. The HEPA filtered air sweeps dirt down to the floor and horizontally to the low wall air returns.Learn more: https://www.americancleanrooms.com/achieving-optimal-airflow-in-cleanroom-design/

Cleanroom gowning for ISO-7 classification cleanrooms

Typically, cleanroom personnel wear cleanroom shoe covers to avoid tracking dirt into the cleanroom. Cleanroom head covering can be a cleanroom bouffant or cleanroom hood. Finally, they wear clean room jackets extending down to operator’s knees. All the garments are manufactured from special non-particulating cleanroom approved materials. Options include disposable or washable (you send back to cleanroom laundry) garments. The cleanroom shoe covers and bouffant caps are typically disposable. It is critical that the personnel wear cleanroom garments if user wants to maintain ISO-7 cleanroom classification. Learn more https://www.americancleanrooms.com/cleanroom-gowning-levels/

Why gown room/airlock for ISO-7 classification cleanroom?

Because an ISO-7 classification cleanroom does 60 air changes per hour, if a door is even briefly opened to the dirty exterior it can take 10 to 15 minutes for the room to restore to class. The gown room/airlock will have HEPA filtration so the recovery time is typically reduced to under 5 minutes. Gown room / airlocks are a critical part of your ISO-7 classification cleanroom. Learn more: https://www.americancleanrooms.com/what-is-a-cleanroom-airlock/

ISO-7 cleanroom classification is a common medium level of the cleanroom classes. The ISO cleanroom standards are set by the International Organization for Standardization (https://www.iso.org/standards.html). They are a private international organization with a membership of 167 national standards bodies

Standards for ISO7 class cleanrooms

ISO 14644-1 (The overarching international standard) https://www.iso.org/standard/53394.html
FED-STD-209E (Class 1000) (The legacy U.S. standard still widely referenced by older engineers)
cGMP / FDA regulations (For pharmaceutical/medical applications) Learn more https://www.fda.gov/drugs/pharmaceutical-quality-resources/current-good-manufacturing-practice-cgmp-regulations
“Validation of Pharmaceutical Processes 3rd edition. Edited by James Agolloco and Frederick J Carleton copyright 2008 Informa Healthcare”
HVAC specifications (Air changes per hour, positive pressure, HEPA/ULPA Fan Filter Units) – American Cleanroom Systems engineering documents.
“ASHRAE design guide for cleanrooms copyright 2017”

FAQS

Is an ISO7 cleanroom cleaner than an ISO6 cleanroom?

No, lower ISO numbers mean stricter cleanliness; ISO6 is cleaner than ISO7

What filter type is required for an ISO7 cleanroom?

HEPA filters—99.97% efficient at 0.3 microns or ULPA filters)

Why is an airlock or gowning room required for ISO7?

To prevent outside contamination from breaching the strict particulate limits when doors open.

What type of filtration and airflow pattern is used in ISO7?

ISO 7 cleanrooms typically utilize laminar airflow where supply air is introduced via ceiling-mounted HEPA filters (which are at least 99.97% efficient at 0.3 microns) and returned through low-wall vents to sweep contaminants out of the space.

The author Anthony Chien has worked at American Cleanroom Systems for past 140 years. He has more than 40 years of cleanroom experience. Anthony has a BS and MS in Electrical Engineering specializing in semiconductor manufacturing from the University of Illinois. He has given more than 15 technical talks on cleanrooms at trade shows and Apple Corporation. American Cleanroom Systems is a design build modular cleanroom manufacturer based in Rancho Santa Margarita CA. It is expert in ISO-45 thru ISO-8 (class 100 to class 100k) modular cleanrooms for pharmaceutical cleanrooms, medical device cleanrooms, and industrial cleanrooms. American Cleanroom Systems has built 16 cleanrooms for US National Laboratories and government agencies.

Property American Cleanroom Systems 2022