[Indoor air public health aspects]

The special attention that needs to be paid to indoor air quality results from the fact that we spend most of the time of the day indoors. Indoor air is polluted by polluted outdoor air (which enters buildings due to ventilation processes) and the numerous sources in indoor spaces. For specific compounds, especially for organic chemicals, concentrations in indoor air exceed those in outdoor air. If indoor air is investigated a sound measurement strategy has to be applied to ascertain that results are obtained that permit a meaningful evaluation. In such evaluation it must not only be checked if there is compliance with guideline values (to the extent that they are available). In addition, the total situation in a room has to be considered. Even though progress has been made since the Concept for Better Indoor Air Quality of the German Federal Government has been published much remains to be done, especially with regard to building products. Improving indoor air quality pays also under the aspect that bad indoor air quality generates costs due to productivity loss and medical treatment.