How does smoking primarily affect lung function?

Smoking primarily impacts lung function by damaging lung tissue and function. The harmful substances in tobacco smoke, such as tar and various chemicals, lead to the inflammation and destruction of the delicate structures in the lungs, including the alveoli, which are essential for gas exchange. Over time, smoking can cause chronic bronchitis and emphysema, both of which significantly reduce lung capacity and impair the ability to breathe efficiently. This damage manifests as decreased airflow, reduction in lung elasticity, and ultimately can lead to chronic obstructive pulmonary disease (COPD).

The other options do not accurately reflect the effects of smoking on lung function. For instance, smoking does not enhance lung flexibility or improve airflow resistance; rather, it restricts airflow and decreases the overall functionality of the lungs. Additionally, rather than increasing alveolar size in a beneficial way, smoking can lead to the breakdown of alveolar walls, resulting in larger but less effective air sacs, ultimately compromising the lung's ability to oxygenate the blood effectively.