Which respiratory condition is characterized by an irreversible obstruction of airflow?

The condition characterized by irreversible obstruction of airflow is chronic obstructive pulmonary disease (COPD). COPD encompasses various lung diseases, including chronic bronchitis and emphysema, that result in a gradual loss of lung function. This obstruction is typically due to long-term exposure to irritants, such as tobacco smoke or environmental pollutants, leading to damage in the airways and lungs that is not fully reversible.

While asthma can also cause airflow obstruction, it is usually reversible with treatment. Chronic bronchitis involves inflammation and narrowing of the airways, which can contribute to airflow limitation but may show some reversibility depending on treatment and cessation of exposure to irritants. Pneumonia, on the other hand, is an infection of the lungs that leads to inflammation and fluid accumulation but does not involve the permanent airway obstruction characteristic of COPD. Thus, COPD distinctly represents a group of conditions defined by long-lasting respiratory issues that lead to permanent airflow limitation.