Airway lumen sizes are smaller in women than men, according to a study published in Radiology. Surya P. Bhatt,  MD, MSPH, and colleagues examined whether structural differences in airways may underlie some of the sex differences in the prevalence and clinical outcomes of COPD. Airway disease was quantified on CT images in a secondary analysis of a multicenter study of never, current, and former smokers enrolled from January 2008 to June 2011 and followed until November 2020. Men had thicker airway walls than women among 420 never smokers, as quantified on CT images for segmental airway wall area percentage, whereas after accounting for height and total lung capacity, airway lumen dimensions were lower in women than men. Among 9,363 ever smokers, greater segmental airway wall area percentage was seen for men, while women had a narrower segmental lumen diameter. Lower FEV1 to FVC ratio, more dyspnea, poorer respiratory QOL, lower 6-minute walk distance, and worse survival were seen in women versus men with a unit change in each of the airway metrics (higher wall or lower lumen measure).