BACKGROUND Chronic obstructive pulmonary disease What is COPD? Chronic obstructive pulmonary disease (COPD) is a preventable and treatable disease characterized by chronic airflow limitation that is not fully reversible. This airflow limitation does not change markedly over several months and is usually progressive in the long term. It is associated with an abnormal inflammatory response of the lungs to noxious stimuli, predominantly smoking (1). Other factors, particularly occupational exposures, may also contribute to the development of COPD. Exacerbations often occur, where there is a rapid and sustained worsening of symptoms beyond normal day-to-day variations (5). In the western world over 90% of causation of COPD is due to cigarette smoking (1;9;13-15). In developing countries, cooking on open fire with subsequent exposure to excessive smoke in close environments, and mining-related pollution can cause COPD too (16) . Morphological changes Exposure to noxious particles, such as cigarette smoke and air pollution over a period can lead to lung inflammation with an associated increased number of neutrophils in the airway lumen and macrophages in the respiratory epithelium and parenchyma. (Figure 1) After years of exposure to noxious particles the lumen becomes narrower. The function of the cilia is impaired and the elasticity in the smooth muscle cell is reduced, and fibrosis occurs. Physiological changes of COPD are characterized by mucous hypersecretion, airflow limitation and air trapping. The mucus hypersecretion will lead to chronic productive cough, a feature of chronic bronchitis, not necessarily associated with airflow limitation. The pathological changes are seen in the proximal airways, peripheral airways, lung parenchyma- and the pulmonary vasculature.