Which statement best describes pulmonary oxygen toxicity?

• A. CNS signs only
• B. Pulmonary symptoms such as cough and chest tightness
• C. Both CNS and pulmonary toxicity
• D. None

Answer: (B)

Pulmonary oxygen toxicity refers to damage in the lungs from breathing high levels of oxygen over time, so the most characteristic signs are those from the respiratory system. Early and typical symptoms include coughing and chest tightness, reflecting airway and alveolar irritation. With continued exposure, lung function can decline and, in longer-term cases, more serious changes like inflammation or fibrosis can develop. CNS signs (such as visual changes or seizures) come from high oxygen levels affecting the nervous system and are not the defining feature of pulmonary toxicity. Therefore, describing pulmonary toxicity by pulmonary symptoms like cough and chest tightness best captures the specific focus of this type of toxicity.