Clean-zone concept

Many firms use the so-called clean-zone concept, in which the restrictions on personnel entering a production area and the required protective clothing are based on the nature of a product— whether the product is prone to the growth of microbes or whether it is required to be sterile. Even for products not required to be sterile or that are not supportive of microbial growth, this concept controls the production environment through reduction of bioburden. 

Cleanroom standard The US Federal Standard 209E, Airborne Particulate Cleanliness Classes in Clean-rooms and Clean Zones, is required for manufacturers who want to conform to quality system regulation. Via the industrial ISO European Community, it has been integrated with ISO. Among the more important recent changes are metrication, revision of upper confidence level (UCL) requirement, provisions for sequential sampling, and an alternative verification procedure based on determination of the concept of ultra-fine particles known as U descriptors. 

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