Chronic respiratory diseases (CRDs) cause enormous burden to the society. In 2016, these diseases were responsible for 3.8 million deaths or 7% of all global deaths. Seventy-five percent of these deaths occurred in those aged 30-69 years, demonstrating that CRDs are not solely a problem for the elderly (1). Chronic obstructive pulmonary disease (COPD) is a major CRD characterized by high prevalence and mortality, and by a persistent and usually progressive airflow limitation associated with different risk factors, the main of which being tobacco smoking and air pollution. Based on multiple large-scale epidemiological studies, the global prevalence of