Conflicts of Interest: The author has completed the ICMJE uniform disclosure form (available at http://dx.doi.org/10.21037/atm-2019-le-08). The series “Lung Emphysema” was commissioned by the editorial office without any funding or sponsorship. BR served as the unpaid Guest Editor of the series and serves as an unpaid editorial board member of Annals of Translational Medicine from Oct 2019 to Sep 2021. The author has no other conflicts of interest to declare.