Table 1. Clinical Differences between Chronic Obstructive Pulmonary Disease (COPD) and Asthma

	COPD	Asthma
Age of onset	Usually > 40 years	Usually < 40 years
Smoking history	Usually > 10 pack-years	Not causal
Allergies	Infrequent	Often
Airway obstruction	Progressive worsening	Variable
Clinical symptoms	Dyspnea on exertion, sputum	Rhinorrhea, cough, wheeze,intermittent and variable dyspnea