a confined area in which the humidity, temperature, particulate matter, and contamination are precisely controlled within specified parameters. The class of the cleanroom defines the maximum number of particles of 0.5-micrometer size or larger that may exist in one cubic foot of air in the designated area . For example, a class 1 cleanroom allows one such particle of any kind to exist in one cubic foot of space; a class 10 area may contain no more than 10 such particles in one cubic foot of space. [SEMATECH]