Final answer:
In obstructive lung disease, a decreased Forced Expiratory Volume in 1 second (FEV1) is most likely. It is accompanied by an increased Forced Vital Capacity (FVC) and a decreased FEV1/FVC ratio.
Step-by-step explanation:
In obstructive lung disease, the most likely spirometry reading to be found is a decreased Forced Expiratory Volume in 1 second (FEV1). Obstructive lung disease, such as Chronic Obstructive Pulmonary Disease (COPD), is characterized by airway obstruction which results in reduced airflow and difficulty in exhaling. As a result, the FEV1 value is decreased. The other spirometry readings that are most likely to be found in obstructive lung disease are an increased Forced Vital Capacity (FVC) and a decreased FEV1/FVC ratio.