An estimated 835,000 people are affected by chronic obstructive pulmonary disease (COPD) in the UK, with a further two million remaining undiagnosed (Shahab et al, 2006). COPD is a chronic progressive lung disease, which makes breathing difficult due to partially obstructed airflow into and out of the lungs. It results from inflammation stimulated by exposure to toxins due to a history of smoking. It is the fifth largest cause of respiratory deaths in the UK (British Thoracic Society, 2006).