The history of race-based correction of lung-capacity measures can be traced to a pre–Civil War belief among slave owners that slaves had naturally inferior lung capacity. Despite work to show that race-corrected spirometers mask lung-disease severity in Black patients, the majority of U.S. hospitals still use them.

A full transcript of this episode is available at https://www.nejm.org/doi/full/10.1056/NEJMp2601975.