Do we need limit values in indoor environment or are reference values sufficient to estimate health risk in indoor air?

Most time of the day adults, but increasingly also children and adolescents in Central Europe, stay in closed rooms. A "good" indoor air quality is therefore very important for the health and well-being of the room users. In addition to ventilation and the possible entry of airborne substances from outside, the entry of chemical and biological substances into the indoor air from sources in the interior itself is decisive for the air quality in indoor environment. Unlike in the outside air or in drinking water area, in Germany there are no limit values for indoor air outside working places with one exception (tetrachloroethylene in the adjacent rooms for chemical cleaning). Instead, reference values are taken. What the benchmark concepts mean and what speaks for and against limit values, especially in the private indoor environment, is set out in this publication.The advantages and disadvantages of both assessment approaches for the indoor environment are presented.