Cleanroom Standards Guide

Cleanroom Standards Guide Swapnali Narkar July 5, 2025

Cleanroom Standards Guide

Introduction

Clean rooms and other critical environments are classified based on their level of airborne contamination, as defined by the ISO 14644-1 standard. This standard has replaced the older US Federal Standard 209E and provides a comprehensive framework for measuring and reporting air cleanliness by counting particles of different sizes in a cubic meter of air.  

Note: The higher the number of particles, the dirtier the room. (ISO 1 most stringent -> ISO 9 least stringent) 

The table below outlines the different classes of clean rooms, the number of particles per cubic meter by micrometer size and typical uses for each ISO
 class. This classification helps ensure that facilities meet the necessary cleanliness standards to protect sensitive equipment and processes.
 

Cleanroom Classification
ClassParticulate Count/m³ by Particle Size(μm)Typical Use
 0.1 μmparticles0.5 μm particles1 μm particles5 μm particles 
ISO 9NA3,52,00,00083,20,0002,93,000General Manufacturing, General Quality Control Laboratories,Consumer Electronics Production
ISO 8NA35,20,0008,32,00029,300Computer rooms
ISO 7NA3,52,00083,2002930Hospital operating rooms, some factories
ISO 610,00,00035,2008,320293Manufacturing computer disk drives, sensitive materials
ISO 51,00,0003,52083229High-purity fi ne chemicals for industrial use and research, ion lithium batteries for electric vehicles, solar panel manufacturing, active medical devices
ISO 410,00035283NALED Manufacturing, High-precision Machining, Satellite Assembly,Photolithography, High-purity Chemical Synthesis
ISO 31,000358NAOptical Fiber Production, Laser Assembly, Aerospace Component Manufacturing, Medical Implants, Production of storage devices like SSDs.
ISO 21004NANAMicroelectronics Fabrication, Production of highly sensitive medical implants, Manufacturing of sterile pharmaceutical products with high sensitivity, Advanced Biotechnology Research, Precision Metrology
ISO 110NANANAAdvanced Semiconductor Manufacturing, Aerospace Instrument Assembly, Ultra-precision Optics. Nanotechnology Fabrication, Genetic Research