Which parameter indicates how much air a person can forcibly exhale in one second?

• A. FVC
• B. PEFR
• C. FEV1
• D. RV

Answer: (C)

The parameter that indicates how much air a person can forcibly exhale in one second is FEV1, which stands for Forced Expiratory Volume in one second. This measurement is a key indicator of lung function and is commonly used in the assessment of respiratory conditions such as asthma and chronic obstructive pulmonary disease (COPD).

FEV1 specifically measures the volume of air expelled during the first second of a forcible expiration following a deep inhalation, reflecting the rate of airflow and the presence of any obstruction within the airways. A lower FEV1 value indicates a potential problem with airway obstruction, as it suggests that the person is unable to expel air quickly and efficiently.

In contrast, Forced Vital Capacity (FVC) measures the total amount of air that can be forcefully exhaled after taking the deepest breath possible but does not focus on the rate at which this air is expelled within the first second. Peak Expiratory Flow Rate (PEFR) reflects the maximum speed of expiration but is a snapshot of the peak flow rather than a specific volume over time. Residual Volume (RV) represents the amount of air left in the lungs after a complete exhalation and does not relate to forced expiration at all. The distinct focus