What is ISO Class 5?

ISO Class 5 cleanrooms refer to cleanroom environments that meet the ISO 14644-1 air cleanliness classification standards for particle counts. Specifically, ISO Class 5 cleanrooms have stringent particle concentration limits that allow them to provide an ultraclean environment for manufacturing, research, medical applications, and other processes requiring controlled contamination levels.

What are the ISO 14644 Standards?

The ISO 14644 standards are a series of internationally recognized specifications published by the International Organization for Standardization (ISO) that classify cleanroom environments based on the concentration of airborne particles. They outline the testing methods required to qualify cleanrooms and establish maximum allowable particle counts per volume of air for different cleanroom classes.

The ISO 14644 standards include:

  • ISO 14644-1: Classification of Air Cleanliness
  • ISO 14644-2: Specifications for Testing and Monitoring to Prove Continued Compliance
  • ISO 14644-3: Test Methods
  • ISO 14644-4: Design, Construction, and Start-up
  • ISO 14644-5: Operations
  • ISO 14644-6: Vocabulary
  • ISO 14644-7: Separative Devices
  • ISO 14644-8: Classification of Surface Chemical Cleanliness

Of these standards, ISO 14644-1 specifically establishes the air cleanliness classification levels from ISO Class 1 (low cleanliness) to ISO Class 9 (extremely high cleanliness).

ISO Class 5 Particle Limits

ISO Class 5 cleanrooms have strict limitations on particle concentrations:

Particle Size Maximum Particle Concentration
≥ 0.1 μm 100,000 particles/m3
≥ 0.2 μm 24,000 particles/m3
≥ 0.3 μm 10,000 particles/m3
≥ 0.5 μm 4,000 particles/m3
≥ 1 μm 400 particles/m3
≥ 5 μm 20 particles/m3

As shown, the permitted particle concentration declines dramatically for larger particle sizes. For example, ISO Class 5 allows no more than 20 particles per cubic meter ≥ 5 μm in diameter. This ensures minimization of contamination from microbes, skin cells, cosmetics, and other particles that may be detrimental in sensitive applications.

How are ISO Class 5 Limits Achieved?

Maintaining ISO Class 5 cleanliness demands a rigorous contamination control strategy encompassing:

  • Air filtration – High-efficiency particulate air (HEPA) filters that remove ≥99.97% of particles ≥0.3 μm.
  • Room pressurization – Positive pressure prevents unfiltered air infiltration.
  • Airflow patterns – Unidirectional laminar flow minimizes particle generation and transport.
  • Room construction – Smooth, impermeable materials, flushed joints, and coved corners facilitate cleaning.
  • Cleaning and disinfection – Routine cleaning procedures eliminate particles on surfaces.
  • Garmenting – Personnel wear coveralls, hoods, boots, gloves, etc. to control shedding.
  • Material control – Parts, tools, and chemicals allowed only through airlocks.

Personnel and activity restrictions also apply. Entry is limited, strict gowning procedures are followed, and movements are controlled to avoid disruption of cleanliness.

ISO Class 5 Cleanroom Applications

The ultraclean environment demanded by ISO Class 5 cleanrooms makes them suitable for:

  • Pharmaceutical manufacturing: Sterile products like injectables, ophthalmics.
  • Medical device fabrication: Implants, catheters, anything that contacts sterile tissues.
  • Microelectronics: Semiconductors, MEMS, optics, hard disk drives.
  • Aerospace: Spacecraft assembly, maintenance of hygiene-critical aviation systems.
  • Healthcare: Surgical spaces, in vitro fertilization labs.

For these uses, ISO Class 5 cleanrooms provide the necessary control of airborne microbes and particles measuring above 0.5 μm that could lead to product contamination, device failure, or infection. The stringency demanded by ISO 14644-1 ensures quality, safety, and reliability.

Unique ISO Class 5 Cleanroom Design Elements

Certain design elements distinguish ISO Class 5 cleanrooms from lower-grade cleanrooms:

  • Airlocks: Entryways incorporating interlocked doors to allow parts transfer while maintaining pressure differentials.
  • Pass-throughs: Small openings with mechanical seal doors for material loading.
  • Gowning rooms: Changing spaces where personnel don cleanroom garments.
  • Separate exit path: Provides personnel egress without backtracking through cleanroom.
  • Buffer zones: Transitional spaces separating lower and higher classification areas.

These aspects allow personnel and material flow while controlling contamination. Other details like lighting, utilities, monitoring systems, and finishes must also meet standards ensuring cleanability, smooth air flow, and particle capture.

ISO Class 5 Cleanroom Construction

Building an ISO Class 5 space requires specialized design and materials, including:

  • Modular wall panels: Interlocking panels with sealed joints construct the cleanroom envelope.
  • HEPA filters: Arrays filter incoming air and recirculated air.
  • Fan filter units: Force filtered air into the cleanroom.
  • Anterooms: Provide transitional space at entry points.
  • ESD-safe floors: Dissipative flooring prevents static discharge.
  • Monolithic coatings: Seamless epoxy or vinyl coatings facilitate cleaning.

Stainless steel, aluminum, or other impermeable materials are used for structural supports, work surfaces, and utilities to minimize particle generation. Smooth finishes, radius corners, and flanged, overlapping joints promote cleanability.

Qualification and Monitoring of ISO Class 5 Cleanrooms

After construction, ISO Class 5 cleanrooms undergo qualification and routine monitoring:

  • Installation qualification (IQ): Validates correct installation of components.
  • Operational qualification (OQ): Confirms all systems function properly.
  • Performance qualification (PQ): Measures particulate and microbial levels meet ISO 14644-1.
  • Environmental monitoring: Regular particle counting ensures continued compliance.

Re-qualification is necessary after any modifications or maintenance that could impact the cleanroom environment.Trends from monitoring data help identify issues for corrective action.

Maintaining ISO Class 5 Conditions

Once qualified, the following protocols preserve ISO Class 5 cleanliness:

  • Access control: Only authorized and properly gowned personnel may enter.
  • Routine cleaning: All surfaces are regularly vacuumed, mopped, disinfected.
  • Filter maintenance: Replace filters per manufacturer instructions.
  • System checks: Verify differential pressures, airflow patterns daily.
  • Gowning inspections: Ensure personnel follow gowning procedures.
  • Material control: Parts are double-bagged, wiped down with alcohol before entering.

Any breach of cleanroom integrity or protocols requires investigation and corrective actions. Personnel must be properly trained in cleanroom disciplines.

Personnel Behaviors in ISO Class 5 Cleanrooms

Unique personnel behaviors required in ISO Class 5 cleanrooms include:

  • Donning full coveralls, hoods, boots, gloves, masks upon entry.
  • Keeping exposed skin and hair covered at all times.
  • Moving slowly and deliberately to avoid stirring up particles.
  • Speaking softly to reduce particle shedding from the mouth.
  • facing downwards when stationary to prevent particles falling from facial area.
  • Exiting only through designated passageways.
  • Showering and changing out of cleanroom garments before leaving.

Violations result in expulsion. Training programs drill personnel on proper cleanroom etiquette to protect the ISO Class 5 environment.


ISO Class 5 cleanrooms provide an elite level of air cleanliness essential for the manufacture of critical products and operation of hypersensitive processes. While expensive to construct and operate, their ultraclean environment protects product integrity and enables advancement across healthcare, technology, and other industries. Strict adherence to ISO 14644-1 standards, ongoing monitoring, and contamination control procedures allows them to remain among the cleanest manmade environments.