In 1992, an isolation campaign (EXEMSI'92) was organised by ESA at DLR premises (Deutsche Forschunganstalt fuer Luft und Raumfahrt). An hyperbaric chamber was used to isolate 4 subjects for 61 days. In the scientific programme of this campaign, a few experiments were dedicated to study volatile organic compounds present in human breath and environment.This paper describes briefly these different contamination experiments, and details the qualitative and quantitative results. Emphasis is made on a method used to identify and measure bioeffluents in human breath and to determine metabolic production rates.Discussion focusses on observed variations and tries to make some comparisons/correlations between results. Recommendations are made for the monitoring and control of atmospheric volatile contamination during space flights.