RESUMO
BACKGROUND: The measurement of carbon monoxide concentration in expired air is used as an objective method to analyze the smoking status. This method has been proven to be reliable and is used throughout the world but it has been only recently accepted in Korea. Therefore the purpose of this study was to examine if measuring the concentration in expired air accurately reflects the Korean's smoking status. METHODS: The subjects were from ages of 19 through 75 healthy people including smokers and nonsmokers. The smokers had their carbon monoxide measured after answering a questionnaire. This questionnaire was formed to obtain information concerning smoking status, smoking habit and factors that influence carbon monoxide measurement. Micro II smokerlyzer (Bedfont Instruments Ltd., England) was used to analyze CO concentration in expired air. The method used for measuring CO concentration was to deeply inhale and hold one's breath for 15 seconds and measure CO concentration while exhaling. RESULTS: The total number of subjects was 148(143 males, 5 females) consisting of 114 smokers, 34 non smokers(never smokers 23, ex smokers 11). The average CO concentration in exhaled air in smokers was 17.247.30 ppm, in nonsmokers 6.031.06 ppm(in ex smokers 6.361.29 ppm, in never smokers 5.870.92 ppm). A significant difference was evident between smokers and non smokers(P<0.0001). The CO concentration values compared among the groups divided in terms of daily smoking rate were as the following 11.885.57 ppm in subjects smoking less than 10 cigarettes/day, 17.356.48 ppm in those smoking 11 20 cigarettes/day, 20.006.35 ppm in the 21 30 cigarettes/day group, and 24.889.70 ppm in the 31 cigarettes/day group (p<0.0001). In addition, the CO concentration was influenced by the change of the degree of inhalation and the elapsed time since last smoking. CONCLUSION: The measurement of CO concentration in exhaled air among the Koreans proved to be an accurate and reliable method reflecting the present smoking status.