In 1864, the year before the Civil War ended, a massive study was launched to quantify the bodies of Union soldiers. One key finding in what would become a 613-page report was that soldiers classified as "White" had a higher lung capacity than those labeled "Full Blacks" or "Mulattoes." The study relied on the spirometer—a medical instrument that measures lung capacity. This device was previously used by plantation physicians to show that black slaves had weaker lungs than white citizens. The Civil War study seemed to validate this view. As early as Thomas Jefferson’s Notes on the State of Virginia, in which he remarked on the dysfunction of the “pulmonary apparatus” of blacks, lungs were used as a marker of difference, a sign that black bodies were fit for the field and little else. (Forced labor was seen as a way to “vitalize the blood” of flawed black physiology. By this logic, slavery is what kept black bodies alive.)
The notion that people of color have a racially defined deficiency isn't new. The 19th century practice of measuring skulls, and equating them with morality and intelligence, is perhaps the most infamous example. But race-based measurements still persist. Today, doctors examine our lungs using spirometers that are "race corrected." Normal values for lung health are reduced for patients that doctors identify as black. Not only might this practice mask economic or environmental explanations for lower lung capacity, but the logic of innate, racial difference is built into things like disability estimates, pre-employment physicals, and clinical diagnoses that rely on the spirometer. Race has become a biologically distinct, scientifically valid category despite the unnatural and social process of its creation.