This part of ISO 14644 provides test methods in support of the operation for cleanrooms and clean zones to meet air cleanliness classifications and related controlled conditions. Tests for classification of cleanliness are described in ISO 14644-1(classification of air cleanliness by particle concentration and for macroparticles). Other related attribute levels can be determined using ISO 14644-8 (levels of air cleanliness by chemicals), ISO 14644-9 (levels of surface cleanliness by particle concentration) and ISO 14644-10 (levels of surface cleanliness by chemical concentration). Performance tests are specified for two types of cleanrooms and clean zones: those with unidirectional flow and those with nonunidirectional flow, in three possible occupancy states: as-built, at-rest and operational. The test methods, recommend test apparatus and test procedures for determining performance parameters are provided. Where the test method is affected by the type of cleanroom or clean zone, alternative procedures are suggested. For some of the tests, several different methods and apparatus are recommended to accommodate different end- use considerations. Alternative methods not included in this part of ISO 14644 may be used if based on agreement between customer and supplier. Alternative methods do not necessarily provide equivalent measurements.