In the last three decades there has been an increasing emphasis on the importance of the use of fidelity assessment on improving the science of psychological, social, and behavioral research.
A cleanroom is an area or enclosure in which the air has to be cleaned to a defined particle limit, usually in particles per cubic foot. In the United States most cleanrooms are discussed in terms of Classification Limits.
The cleanest cleanroom is a class 1 and the dirtiest a class 9. ISO class 3 is approximately equal to FS209E class 1, while ISO class 8 approximately equals FS209E class 100,000. In November 2001, Federal Standard 209E was superseded by the new ISO 14644-1 international standards.