This guide describes standardized procedures for determinationof the concentration of airborne particles in the ultrafine sizerange (i.e., particles with a size distribution having a threshold[lower limit] particle size smaller than 0.1 Âµm). The numericalvalue of the concentration of such particles, expressed in terms ofparticles per cubic meter, is the U descriptor. This term may referto a specified concentration of ultrafine particles or tomeasurement of the concentration of ultrafine particles in a givensample of air.
The procedures described herein are suitable for use inconjunction with related cleanroom standards, such as ISO 14644-1for determination of airborne particulate cleanliness, and ISO14644-2 for monitoring. The procedures are applicable to cleanroomsand clean zones in any of three occupancy states, as defined in ISO14644-1.
This document is most appropriate for use with cleanroom andclean zone environments that qualify as ISO Class 4 or cleaner, asdefined in ISO 14644-1.