This part of ISO 14644 covers the classification of air cleanliness in terms of concentration of airborne nanoparticles.
For classification purposes, only populations of particles smaller than 0.1 microns (100 nm) - 'nanoscale' - are considered.
NOTE. For the purposes of this document, reference will be made to 'nanoparticles', which here signify all nano-objects having one, two or three dimensions in the nanoscale.
This classification extends the particulate classification specified in ISO 14644-1 into the nanoscale (< 100 nm) region.