Dr. Barr's research focuses on the epidemiology of respiratory disorders, with particular attention to chronic obstructive pulmonary disease (COPD), emphysema and related syndromes. He has shown that heart and lung function are closely related, even in subclinical disease, and is examining pulmonary vascular changes in early COPD, which may suggest novel therapeutic and preventive approaches to this disorder, which is a major public health problem in the United States.