Chronic obstructive pulmonary disease (COPD) refers to chronic bronchitis and emphysema, is a progressive disease that makes it hard to breathe. "Progressive" means the disease gets worse over time. In contrast to asthma, the limitation of airflow is poorly reversible and usually gets progressively worse over time.

Cigarette smoking is the leading cause of COPD. Smoker is more prone to have COPD compare to non smoker. Long-term exposure to other lung irritants, such as air pollution, chemical fumes, or dust, also may contribute to COPD.

The prevalence of COPD was estimated 4.7% 3(448 000 people) for adult Malaysian population in 2003. The prevalence is expected to rise and be driven by cigarette smoking. In Malaysia, COPD is frequently diagnosed in the late stages of the disease where treatment options are limited and expensive. The outcome of treatment in most cases is poor. Furthermore, COPD patients with recurrent exacerbations had an accelerated and sustained decline in lung function, quality of life; and sometimes, die from the exacerbation.