Which of the following is NOT a common respiratory disease?

Heart disease is classified primarily as a cardiovascular disease, affecting the heart and blood vessels rather than the respiratory system. The other conditions listed—asthma, lung cancer, and chronic obstructive pulmonary disease (COPD)—are all directly related to the respiratory system. They involve the lungs and airways, impacting how oxygen is exchanged and how effectively a person can breathe. Asthma is characterized by inflammation and narrowing of the airways, lung cancer involves the growth of malignant cells in the lungs, and COPD refers to a group of lung diseases that block airflow and make it difficult to breathe. Thus, while heart disease is a significant health issue, it does not fall into the category of common respiratory diseases.