The ISO 14644-1 standard defines a cleanroom as:

“a room within which the number concentration of airborne particles is controlled and classified, and which is designed, constructed and operated in a manner to control the introduction, generation and retention of particles inside the room.”

This definition is followed by 3 notes:

1) “The class of airborne particle concentration is specified.”

2) “Levels of other cleanliness attributes such as chemical, viable or nanoscale concentrations in the air, and also surface cleanliness in terms of particle, nanoscale, chemical and viable concentrations might also be specified and controlled.”

3) “Other relevant physical parameters might also be controlled as required, e.g. temperature, humidity, pressure, vibration and electrostatic.”

To meet the requirement for controlling the concentration of airborne particles, a cleanroom is supplied with air which is filtered through HEPA (High Efficiency Particulate Air) or ULPA (Ultra Low Penetration Air) filters. The filtered air dilutes and removes particles from the room and is also used to pressurise the area.

Dependent on your requirements, Cleanrooms may also be Single Pass, where all air entering the room is preconditioned fresh air and this is passed out to the surrounding environment, having undergone a filtration process where necessary.

Temperature and Humidity in the cleanroom may be controlled by HVAC or independent heating/cooling units and humidifiers/dehumidifiers as required.

Cleanrooms must be built with materials that do not generate particles and staff working in the cleanroom must wear garments that minimise the dispersion of particles. Cleanroom garments must protect the environment from the microorganisms that can be generated by people.