CIGARETTE-SMOKING AND ETHANE EXHALATION IN HUMANS

The time course of exhaled ethane gas was determined in the alveolar e xpirate of healthy, fasting smokers and nonsmokers after smoking a cig arette. Baseline ethane was measured by gas chromatography and correct ed for background ethane after a 2-min washout using purified air. Eth ane was measured immediately after smoking and hourly thereafter. Etha ne was highest immediately after smoking, reflecting ethane in cigaret te smoke. An exponential decline of ethane in smokers returned ethane to baseline within 3 h. Ethane in nonsmokers also peaked immediately a fter smoking but returned to baseline by 1 h. Ethane from smokers, mea sured 3 h after the last cigarette, was compared with ethane from heal thy ex-smokers and nonsmokers. Mean (+/- SEM) baseline ethane in smoke rs was 2.90 +/- 0.52 pmol/min/kg, 1.55 +/- 0.36 pmol/min/kg in ex-smok ers and 1.11 +/- 0.26 pmol/min/kg in nonsmokers (p < 0.05). Ethane in two smokers measured before and after a week of oral beta carotene sup plementation (60 mg/d) fell by 80 and 35%. We conclude that cigarette smokers have increased baseline ethane in exhaled breath compared with non-smokers. Trials with antioxidant agents are warranted to assess t heir ability to reduce expired ethane levels.