[The concept of hygienic evaluation of multicomponent chemical contamination of air on piloted orbital stations].

Air quality monitoring on piloted orbital stations (OS) showed that the multicomponent air contamination largely comes from technical sources defining the quantitative and qualitative dynamics and occasional sharp surges of contamination. Another pervasive factor is secondary, more toxic compounds resulting from transformation of chemicals. The toxico-hygienic qualification of the general chemical background should be made with reference to the next functional levels: bioneutral, threshold and admissible. Based on experiments, long-term presence of a multitude of airborne chemicals in trace concentrations or much below MACs (bioneutral) does not have an additive effect on human organisms and can be neglected in evaluation of the total toxicity of chemicals. Hygienic criteria should be set to the compounds that are liable to mount to the threshold and admissible concentrations. The concept of hygienic evaluation of multicomponent chemical contamination of OS air substantiates an integral estimation of the total chemical exposure of humans with good knowledge of effects of a combination of chemicals taken as the air quality markers, intermittent surges of contamination twice as high as time-average MACs, and intensity of secondary toxic contamination.