Smoking Cessation, Stages of Change Cigarette smoking is the single leading cause of preventable death and disease in the United States. But because of the physical and psychological addiction to nicotine, smokers find it quite difficult to quit. This video offers important reasons to stop smoking and a framework of change to help you achieve your goal. Pulmonary Function Tests Podcast These tests assess lung volumes, capacities, rates of flow, and gas exchange. Different procedures measure lung function in different ways.