Classification of Small Airways

We thoroughly enjoyed the article published in the July 2021 issue of CHEST by Usmani et al.1 It provided good insight into the pathophysiology of the small airways in obstructive airway disease. However, on page 115, in their description of the small airways, the authors wrote that “they incorporate the final eight divisions on the airways, comprising respiratory bronchioles, alveolar ducts, and alveolar sacs.”