Spanning every subject of critical importance to the field of environmental monitoring, this guide offers step-by-step guidance on the assessment of air, surfaces, water, action levels, instruments, and procedures in cleanroom facilities. Emphasizing the importance of data gleaned from evaluation and sampling studies, this guide shows how to use this information to reduce contamination risks and provide safe and stable operating conditions for the development of pharmaceutical products. This reference also covers certification/requalification and new ISO standards.