Characterization of human expired air: a promising investigative and diagnostic technique.

Expired air samples have been collected from a carefully selected population of normal healthy human subjects under controlled experimental conditions. The samples were concentrated and analyzed by quantitative, reproducible and sensitive techniques which resulted in well-defined composite compositional and occurrence profiles of the organic constituents present in normal expired air. The composite profiles provide valuable baseline information upon which suitable correlation studies may be advanced toward the use of human expired air for diagnostic purposes.