Call us: 022 4970 1393
Email us:

ISO 14644 -1


  • Part 1: Classification of air cleanliness by particle concentration
  • Part 2: Monitoring to provide evidence of cleanroom performance related to air cleanliness by particle concentration
  • Part 3: Test methods
  • Part 4: Design, construction, and start-up
  • Part 5: Operations
  • Part 7: Separative devices (clean air hoods, gloveboxes, isolators and mini-environments)
  • Part 8: Classification of air cleanliness by chemical concentration (ACC)
  • Part 9: Classification of surface cleanliness by particle concentration
  • Part 10: Classification of surface cleanliness by chemical concentration

ISO 14644-1

This section specifies the classification of air cleanliness in terms of concentration of airborne particles in cleanrooms and clean zones.

Only particle populations having cumulative distributions based on the threshold particle sizes ranging from 0.1 µm to 5.0 µm are considered for the classification purposes.

The use of light scattering (discrete) airborne particle counters (LSAPC) is the basis for determination of the concentration of airborne particles, equal to and greater than the specified sizes, at designated sampling locations.

Apex Z3 – 1 CFM Portable Airborne Particle Counter

An M descriptor (see Annex C) may be used to quantify populations of macroparticles (particles larger than 5.0 µm).

This part of ISO 14644 cannot be used to characterize the physical, chemical, radiological, viable or other nature of airborne particles.

How to determine the number of sample locations:

  • Location Number =√Area
  • For all rooms larger than 1000 square meter use Formula below formula:
  • NL = 27 × 𝐴rea / 1000

ISO14644-1:2015 New Maximum Concentration Limits

De-emphasis of the ≥ 5 µm ISO Class 5 limit

  • Sampling and statistical limitations for particles in low concentrations make classification inappropriate.
  • In order to specify this particle size in association with ISO Class 5, the macroparticle descriptor ‘M’ may be adapted and used in conjunction with at least one other particle size.
  • Sample collection limitations for both particles in low concentrations and sizes greater than 1 μm make classification at this particle size inappropriate, due to potential particle losses in the sampling system.