The setting of limit values for environmental noxae is essentially based on measurements and data from single exposures. To an increasing degree, however, there are demands also to consider combined exposures. Hence, in this study, the necessity and feasability of environmental standards for combined exposures have been examined from the scientific, medical, economic, legal, sociological and philosophical/ethical perspective. Starting from effect mechanisms, criteria have been established which, in spite of the complexity of the issues, enable us to set limit values in order to achieve given environmental quality targets. This study endeavours to reveal and explain gaps in knowledge and to point to possible solutions from the scientific and medical point of view. The results should support efforts to shape a practical legal framework and viable economic procedures for environmental standards on combined exposures, taking into consideration the standards and perceptions existing in our communities.