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Smoking in pack-years as a risk factor for COPD, showing significant site heterogeneity in risk among the nine sampling sites. Results are shown for men and women and for the whole cohort. COPD was defined by airflow limitation (FEV1/FVC < LLN); ES (95% CI) is the adjusted odds ratio and 95% confidence interval, aOR (95% CI) for every 10-pack-year increase, adjusted for age, school years, asthma, childhood hospitalization, and dusty job exposure.
