Smoking and ambient and home air pollution were identified as the leading drivers of death and disability from chronic obstructive pulmonary disease by the Global Burden of Disease study (COPD). A measurable feature of COPD, related to various risk factors to calculate the probability of chronic airflow obstruction (CAO). The Burden of Obstructive Lung Disease study is a cross-sectional study of persons aged 40 and up in 41 urban and rural areas worldwide. Researchers calculated the prevalence of CAO, defined as a postbronchodilator FEV1-to-FVC ratio less than the lower limit of normal, and the relative risks associated with different risk variables using data from 28,459 patients. 

A Bayesian hierarchical model was used to assess local relative hazards using data from many sites. Researchers calculated local population attributable risks based on these relative risks and the prevalence of risk variables. CAO was prevalent in 11.2% of males and 8.6% of women. Men had an attributable population risk of 5.1%, while women had 2.2%. Poor education, ten years of working in a dusty job, a low body mass index, and a history of tuberculosis was the next most influential risk factors. The risk of CAO associated with the various risk variables differed between sites. Although smoking is still the most important risk factor for CAO, inadequate education, a low BMI, and passive smoking are more important in some places. At some locations, dusty jobs and tuberculosis are significant risk factors.