洁净区CleanZone　在洁净厂房设计规范GB50073-2001的定义为：空气悬浮粒子浓度受控的限定空间。它的建造和使用应减少空间内诱入、产生及滞留粒子。空间内其他有关参数如温度、湿度、压力等按要求进行控制。洁净区可以是开放式或封闭式。

洁净区CleanZone 在ISO14644-1-1999中定义为：dedicated space in which the concentration of airborne particles is controlled, and which is constructed and used in a manner to minimize the introduction, generation, and retention of particles inside the zone, and in which other relevant parameters, e.g. temperature, humidity, and pressure, are controlled as necessary NOTE This zone may be open or enclosed and may or may not be located within a cleanroom.

洁净室与洁净区的区别：洁净区是空气悬浮粒子浓度受控的限定空间，而洁净室的定义为空气悬浮粒子浓度受控的房间，一个是房间一个是空间，不难看出，洁净室是指一个小的受控房间而洁净区则是可以包含多个这样的洁净室。