The New York Post recently featured a story about an individual of Indian ancestry who is suing the Fire Department of New York for discrimination in the hiring practices. He passed all the entrance exams but failed the pulmonary function test (PFT). This individual claimed that these test metrics discriminate against various ethnic or racial groups. On the surface this story seems like another frivolous lawsuit, but is it? There is actually a scientific basis for his claim.
What are Pulmonary Function Tests?
It is a method of screening the function of the lungs. A chest X-ray provides a picture of the anatomy of the lungs, but does not tell you how well they function. A pulmonary function test (PFT) first measures how much air can be expelled from the lungs, after they are filled to maximum. That part of the test is known as the Forced Vital Capacity (FVC). Next the test measures how fast the air can be expired, forced expiratory volume in one second or FEV1. This specific step is an important measurement when evaluating conditions that affect the airways, such as asthma and COPD, where there is narrowing of the airways which causes a slowing of the flow of air. There are several other measurements that can be assessed during a full PFT, including lung volume compartments and diffusion capacity, but for now let’s keep it simple.
Differences in Normal PFT Values
What is relevant to this story is the question of what constitutes normal values? As a person ages, the natural elasticity of the lungs decreases and this affects the flow of air. So there are different normal values for different age groups. Height will also determine different normal values, so specialists must correct the measurements by factoring in the size of the individual. Finally, there are also gender differences that have to be factored into the final calculations. So for every test there are the measured values and then, how they are, compared to the normal values that would be expected for this individual.
How were the standard normal values determined?
The tables of normal values commonly used by most laboratories are called the Knudsen and Bohousse tables, which were derived from a designated population of Scandinavian descent. You would think, as the U.S. Constitution says, that “all men are created equal,” but scientific evidence suggests that there are anthropomorphic differences between races. It is postulated that African Americans have a smaller trunk proportional to their height, and their legs are larger. The net result is that their lung volumes are 12 percent smaller than their Scandinavian counterparts.
There are other variables that impact PFT results, such as the environment where one lives, the size of a person’s abdomen which can impact how completely the lungs expand, and the person’s performance at the time of the test.
Obviously pulmonary function should be interpreted according to the clinical context of the patient. The PFT is useful when the doctor orders the screening to assess a specific situation. It should not be used on the general population as a routine or general screening. Unfortunately, screenings are frequently used on individuals who practice in specific occupations, like welders and spray painters, who need to use tight fitting respirator-type masks.
Not taking into account individual differences, including ethnicity, may be proven unfair as claimed by the litigant in the New York Post story. We’ll have to wait and see how that story turns out.
Eli Hendel, M.D., is a board-certified internist/pulmonary specialist with board certification in Sleep Medicine. An Assistant Clinical Professor of Medicine at Keck-University of Southern California School of Medicine, and Qualified Medical Examiner for the State of California Department of Industrial Relations, his areas include asthma, COPD, sleep disorders, obstructive sleep apnea, and occupational lung diseases. Favorite hobby? Playing jazz music. Find him on Twitter @Lung_doctor.