Asthma is a common lung disease affecting about 300 million people worldwide. In Malaysia it is estimated about 1.5 million people of all ages suffer from asthma. As many as 50% children with asthma missed school and about a third of adults missed work because of asthma and many of these patients had to be hospitalized and experienced symptoms of uncontrolled disease. Suboptimal treatment and inadequate knowledge about the illness are factors contributed to poor control of asthma.

Chronic ventilatory failure (CVF) is a progressive, long-term condition where the respiratory system cannot adequately remove carbon dioxide (CO_{2}) or supply oxygen, often resulting in chronic hypercapnia (high blood (CO_{2})) and/or hypoxemia (low blood oxygen). It is generally caused by underlying chronic diseases like COPD, obesity hypoventilation syndrome, or neuromuscular disorders. Management includes long-term non-invasive ventilation (NIV), oxygen therapy, and treating the underlying cause. 

Chronic obstructive pulmonary disease disease affects almost exclusively adult smokers. Initial symptoms include cough with sputum production and difficulty in breathing initially on severe exertion but later on may be so debilitating that even walking a few steps can be a real struggle. In the terminal stage of the illness many patients would require continuous oxygen supplement to alleviate their breathlessness.

Bronchopulmonary dysplasia is a lung disease that occurs in premature neonates who needed oxygen therapy or mechanical ventilation during their early lives. The lung damage can be severe that long term oxygen may be required for many of these infants for a considerable period of time.