This part of ISO 16000 is intended to aid the planning of indoor pollution monitoring.Before a sampling strategy is devised for indoor air monitoring, it is necessary to clarify for what purposes, when, where, how often and over what periods of time monitoring is to be performed. The answers to these questions depend, in particular, on a number of special characteristics of the indoor environments, on the objective of the measurement and, finally, on the environment to be measured. This part of ISO 16000 deals with the significance of these factors and offers suggestions on how to develop a suitable sampling strategy. This part of ISO 16000 is applicable to