EFFECT OF AGING ON THE CONCENTRATIONS OF NITROUS-OXIDE IN EXHALED AIR

Trace gases in exhaled air have been used as a simple means of assessi ng metabolic reactions. The investigations of trace gases derived from bacteria in human exhalation are usually hydrogen (H-2) or methane (C H4). On the other hand, nitrous oxide (N2O) is also derived from micro organisms, especially denitrifying bacteria. Although many kinds of de nitrifying bacteria have been isolated on and in the human body, there has been few concerning N2O. We studied 222 healthy people from the a ge of 5 to 85 years. The analysis of N2O in exhaled air was carried ou t by a infrared-photoacoustic (IR-PAS) analyzer. It was found that N2O ranged from 0 to 1670 ppbv in exhaled air and that 59% (131) of the s ubjects were producers of N2O. A highly significant relationship was o bserved between age and concentrations of N2O (r = 0.40, P < 0.01). Th e rate of production in young children and in the aged was significant ly higher than that in adults aged 20-39 years (P < 0.01), and less th an 30% were producers during puberty. The change of normal microflora on and in human body with aging may have caused the significant relati onship between age and emissions of N2O. (C) 1997 Elsevier Science B.V .