General and substance-specific aspects of the measurement strategy to be taken into account before and during sampling as well as measurement procedures for individual substances or groups of substances in indoor air are described in the single parts of DIN EN ISO 16000. DIN EN ISO 16000 Part 1 deals with the general aspects of the measurement strategy. This standard is of special importance as principle procedures for ventilation and the setting of the room temperature before and during sampling are specified. Indoor air measurements are mainly undertaken for the following five reasons, of which the first may be unrelated to, or may evoke the other four: a) complaints by users about poor air quality, b) the need to determine the exposure of occupants to certain substances, c) the need to measure whether specified limit or Guideline values are being maintained, d) testing the effectiveness of remedial treatment, e) observed or suspected health effects of the occupants. In the standard the corresponding procedures for sampling and the boundary conditions to be observed are described in detail.