What statement best defines a pulmonary toxin?

• A. A substance that improves lung function.
• B. A substance that causes skin irritation only.
• C. A substance that irritates or damages the lungs.
• D. A substance that eliminates respiratory symptoms.

Answer: (C)

A pulmonary toxin is any substance that irritates or damages the lungs when inhaled, impacting the respiratory tract and gas exchange. Exposure can cause immediate effects like coughing, wheezing, and chest tightness, and with longer exposure may lead to inflammation, edema, or scarring that impairs breathing.

So the statement that best fits this definition describes a substance that irritates or damages the lungs. The other options describe effects that aren’t about harming the lungs: one says it improves lung function, another limits itself to skin irritation, and another suggests it eliminates respiratory symptoms.