Chronic bronchitis clinically is chronic or recurrent productive cough for at least 3 consecutive months for not less than 2 consecutive years. The radiographic findings are nonspecific to include hyperinflation, areas of pulmonary oligemia, tubular "tram tracks", and airway wall thickening (thickened bronchial walls) when seen circular on end often appear as "signet rings". The increase in bronchovascular markings creates the typical "smokers lung" or so called "dirty lung".