In the work-place environment MAK values (maximum allowable workplace concentrations) haven been fixed as time-integrated averages relatively early in order to avoid adverse health effects to workers exposed to air pollution during their working shift. Similarly, MIK values (maximum immission concentrations have been set up to protect the health of the total population. In contrast to this, there are no limit values for pollutant concentrations in non-working place indoor environments. The problem of applying the MIK and MAK value concept to the non-industrial indoor environment is discussed. In this context, mention is also made of the possibility of an indirect uptake of deposited dust or of a diffusion of gaseous components into foodstuff and of other exposure pathways. The discussion shows that the reference to MIK and MAK values can only lead to a first approximation in the evaluation of a non-industrial indoor situation. Further studies are needed to establish limit values for special indoor air pollutants. In this context, the usefulness of the concept of the so-called BAT value for indoor purposes is discussed (BAT = Biologischer Arbeitsstoff-Toleranzwert). It will be an urgent matter to set up emission standards for building materials, furniture, textiles, paints and other possible emitters in order to protect the population from preventable exposure.