Why cant you smoke before a cardio-pulmonary exercise test?

Smoking before a cardio-pulmonary exercise test can significantly affect the test results by altering heart rate, blood pressure, and lung function. It can introduce variability in oxygen consumption and carbon dioxide production, leading to inaccurate assessments of cardiovascular and pulmonary health. Additionally, smoking can cause airway irritation and reduce exercise tolerance, compromising the test's ability to evaluate an individual's true exercise capacity.