“…The mass-spectrometer response time is influenced by the transport time from the sampling site to the instrument, the response time of the instrument and the sampling frequency (Noguchi, Ogushi, Yoshiya, Itakura & Yamabayashi, 1982). If the transport time is measured (Beaver, Wasserman & Whipp, 1973;Pearce, Milhorn, Holloman & Reynolds, 1977) or assumed (Cochrane et al 1982;Linnarsson, 1974, Davies, Hahn, Spiro & Edwards, 1974 but the response time is ignored, there are systematic errors in 202 and yco2 measurements when these are compared to values obtained by simultaneous expired gas collection (Noguchi et al 1982). Several complex methods to correct for the instrumental response time have been developed (Noguchi et al 1982;Mitchell, 1979;Arieli & van Liew, 1981;Beaver et al 1981) that are all standardized against steady-state expired gas collections.…”