Histological measurements in cases of severe paniobular and centrilobular emphysema and in normal lungs disclosed a generalized thickening of the walls of small airways in the panlobular group. With mathematical models, this was depicted as a potential basis for airway closure at higher than normal lung volumes and trapping of air. Lungs with mixtures of panlobular and centrilobular emphysema predominate in the general population, and the obstructive component of airways in this setting is likely a net result of multiple lesions. These may be common in varying degrees to both varieties of disease but especially characteristic of one form. Bronchiolar thickening is one such general process. Present findings suggest that this is prone to be linked to emphysema with a panlobular pattern.