The concentrations of ammonia, acetone, methanol, ethanol, propanol and hydrogen cyanide have been measured in the exhaled breath of 26 young adults of age 17/18 years, using selected ion flow tube mass spectrometry (SIFT-MS). Thus the concentration distributions have been constructed and are seen to be essentially log normal with median values in parts per billion (ppb), being ammonia, 317; acetone, 363; methanol, 238; ethanol, 104; propanol, 13; hydrogen cyanide (HCN), 8. There is a clear separation in the median breath ethanol levels between those volunteers who had ingested sugary food/drinks (109 ppb) and those who had not (48 ppb). These data are compared with the results of a study of the same breath compounds, excepting HCN, for a similar sized cohort of healthy volunteers within the age range of 20 to 60 years, which shows that the median levels of these compounds are lower in the young adult volunteer cohort. These HCN measurements are the first to be made in the breath of healthy individuals. The potential implications of these combined results for clinical diagnosis are alluded to.