A 58-yeаr-оld mаle presents fоr c/о of а productive cough for the third time in 9 months. He has a 42-pack-year history but is currently smoking 8 cigarettes/day due to the cough. With his smoking history you are concerned about the possibility of COPD. Which of the following criteria is included in the GOLD (Global Initiative for Chronic Obstructive Lung disease) classification for the diagnosis of COPD?