Interpreting spirometry as normal or abnormal using 95% confidence limits can obscure milder airflow decreases. Other analyses might better persuade cigarette smokers to quit.High-quality spirometric data of ambulatory never-and current-smokers of African-, Europeanand Latin-American ethnicity from the Third National Health and Nutrition Evaluation Survey (n.9000) were analysed. We desired to calculate, for each decade of life, the odds that specific ratios of forced expiratory volume in 1 s to 6 s (%FEV1/FEV6) and to forced vital capacity (%FEV1/ FVC) values came from a current-or never-smoker. We also desired to develop new, simpler and better formulas to estimate changes in physiological lung age (Dlung age) for males and females.For each decade of life, odds increase strikingly that smoking decreases %FEV1/FEV6 and %FEV1/FVC. At least for these three ethnicities, Dlung age can be easily calculated as the product of (predicted -actual) %FEV1/FEV6 6 4 or (predicted -actual) %FEV1/FVC 6 3. Through the sixth decade of life, smokers' Dlung age increase rapidly but little thereafter, presumably due to the inabilities of older smokers to participate in the survey or their deaths.Using odds and Dlung ages rather than traditional 95% confidence limits might better persuade smokers to quit. KEYWORDS: Chronic obstructive pulmonary disease, lung age, ratio of forced expiratory volume in 1 s to 6 s, ratio of forced expiratory volume in 1 s to forced vital capacity, spirometry