The German approach to regulate indoor air contaminants

Indoor air quality (IAQ) and exposure to indoor chemicals are widely discussed in terms of personal discomfort and health risks. In contrast to ambient air and working environments, legally binding regulations are only partially established for indoor contaminants, and other available European guidelines are limited. To correct these deficits, the German Committee on Indoor Guide Values (AIR), formerly known as the Ad hoc Working Group (Ad hoc AG), performed health assessments of indoor air contaminants. The main tasks were to develop toxicologically based indoor air guide values, health-based guideline values, and reference values largely based on the 95th percentile of the concentrations found in a reference population. Here, we provide a comprehensive overview of the indoor air values set in Germany and discuss the basis of their derivation. This overview includes a description of legally binding standards, indoor air guide values for 38 substances or groups, and guidelines for TVOC (total volatile organic compounds), particulate matter, and carbon dioxide as well as risk-related guidelines for carcinogenic substances.