This part of ISO 14644 covers the classification of air cleanliness by particles (ACP) in terms of concentration of airborne nanoscale particles. For classification purposes, only populations of particles with a lower size limit of 0.1 microns (100 nm) or less - "nanoscale" - are considered. The classification given in this document is for use mainly in "in operation" states. This classification extrapolates the particulate classification equation specified in 14644-1 into the nanoscale (<100 nm) region.
