What is the main characteristic of Chronic Obstructive Pulmonary Disease (COPD)?

Chronic Obstructive Pulmonary Disease (COPD) is primarily characterized by chronic obstruction of airflow in the lungs. This obstruction is typically progressive and associated with an abnormal inflammatory response of the lungs due to harmful particles or gases, most commonly from smoking.

The key aspect that defines COPD is the impairment in airflow that does not fully reverse, distinguishing it from other respiratory conditions. Patients often experience a limitation in airflow during both exhalation and inhalation, leading to difficulty breathing, especially during physical activity.

Moreover, while there may be other related conditions or symptoms, such as changes in lung volumes or erythropoiesis due to chronic hypoxemia, these do not define COPD as directly as the chronic airflow obstruction does. Understanding this core characteristic is crucial for diagnosing and managing COPD effectively.