ISO 14644-1 classifies cleanrooms based on the concentration of airborne particles. The cleanroom classes range from ISO 1 to ISO 9, with ISO 1 being the cleanest. For example, an ISO 1 cleanroom allows a maximum of 10 particles per cubic meter of air, whereas an ISO 9 cleanroom can have up to 35,200,000 particles per cubic meter. The classification is crucial for nanotechnology applications because even tiny particles can cause significant issues.
