SELECTION OF ROUTINE SITES The qualification study should include sufficient replicates under conditions both “at rest” and “dynamic” to allow identification of sites that provide useful information. It should be clarified that the term “useful information” is not meant to describe those sites that give the most desirable counts but rather those sites that either give the highest counts (i.e., serve as the most sensitive measure of the state of control of the room) or were shown to be appropriately placed to herald a problem in the room. The number of sites in a room or zone should similarly be driven by data generated during this study. Both the number and location of sites or each clean room or zone should be justified in the report from this qualification study. The following section (X.1.A) from the FDA guidance (8) is relevant for consideration: “All environmental monitoring locations should be described in SOPs with sufficient detail to allow for reproducible sampling of a given location surveyed. Written SOPs should also address elements such as 1. frequency of sampling, 2. when the samples are taken (i.e., during or at the conclusion of operations), 3. duration of sampling, 4. sample size (e.g., surface area, air volume), 5. specific sampling equipment and tech- niques, 6. alert and action levels, and 7. appropriate response to deviations from alert or action levels.”