Pulmonary function testing shapes nearly every major decision in respiratory care, including diagnosis, disease staging, and treatment selection. When used well, it improves clinical outcomes. However, its benefits have not been equally realized across patient populations.
Black Americans have higher rates of asthma, as well as emergency department visits and mortality due to asthma-related complications, than White Americans. These disparities are a consequence of well-documented drivers, such as exposure to polluted air, housing patterns, access to care, and insurance barriers.¹
Pulmonary function testing itself does not create those differences in risk, says Cedric Rutland, MD, a pulmonologist and allergist based in Southern California. For generations, race has been built into the reference equations that define normal lung function in the United States. The use of race-based adjustment has led to lower predicted benchmarks for certain populations, raising the threshold for what qualifies as impairment and potentially delaying disease recognition and escalation of care.
If you want to diagnose more lung disease, stop using race in pulmonary function testing.
“The outcomes are what they are based on the established benchmarks,” notes Dr Rutland, a triple board-certified Pulmonary, Critical Care, and Internal Medicine physician who frequently speaks about asthma disparities through his volunteer work with the American Lung Association. “The question is why — and that’s where we have to start looking at how we’re measuring disease.”
Referring to the race-adjusted reference equations, he adds: “Once the test tells you they’re normal, everything downstream slows down.”
That slowdown can mean delays in follow-up, treatment escalation, or referral to specialty care. In communities with high rates of environmental and structural risk factors, those delays can carry serious — and sometimes fatal — consequences.
“If you want to diagnose more lung disease,” Dr Rutland says, “stop using race in pulmonary function testing.”
How Pulmonary Function Testing Came to Define “Normal”
Although spirometry is integral to modern respiratory care, its interpretation rests on assumptions that date back more than a century.
Spirometry emerged in the late 19th century and became widely standardized in the mid-20th century as clinicians sought an objective way to distinguish normal variation from confirmed disease. Over time, reference equations were developed to translate raw airflow measurements into predicted values and lower limits of normal. Age, height, and sex were included because they influence lung mechanics and size.2
Race was later incorporated into reference equations based on observed differences in lung volume across diverse groups. These differences in lung health were attributed to biological rather than environmental or occupational factors at that time.3
“There’s nothing about lung size that’s based on the color of someone’s skin,” Dr Rutland says. “The Black individuals from whom those volumes were taken had a disease. They were exposed to pollution. They were working in the fields. They were breathing in inflammation.”
As spirometry software standardized these equations, race-adjusted predicted values became routine in clinical practice, influencing thresholds used to diagnose disease, stage severity, and determine eligibility for treatment.²
Race-adjusted reference equations are still part of many pulmonary function testing systems. The American Thoracic Society states that race-specific adjustments have historically resulted in lower predicted values for Black patients than for White patients of the same age, sex, and height.3
In practical terms, Dr Rutland says, Black patients can present with symptoms and still appear “normal” on paper.
National data underscore the stakes. Black Americans are approximately 40% more likely than White Americans to have asthma, nearly 5 times more likely to visit the emergency department for asthma-related care, and 2 to 3 times more likely to die of asthma-related complications. Asthma-related mortality rates are highest among Black women and Black children.4
What the Data Show When Race Is Removed
Recent analyses show that replacing race-specific equations with race-neutral standards would reclassify abnormal lung function for an estimated 12.5 million Americans. In adjusted models, impairment classification increased by 141% among Black individuals and decreased by 69% among White individuals. Other studies have found that race-specific equations underestimate mortality risk and chronic obstructive pulmonary disease severity in Black adults.5-6
Although previous research has not directly linked race-neutral spirometry to improved asthma outcomes, it shows something clinically concrete: When race is removed from the equation, more Black patients meet criteria for impairment.
“Change the benchmark, and you change who gets labeled sick,” Dr Rutland says.
In a 2023 official statement, the American Thoracic Society concluded that race should not be used as a biological adjustment in pulmonary function test interpretation. The Society emphasized race is a social construct rather than a determinant of lung size and recommended transitioning to race-neutral reference equations, with corresponding updates to clinical infrastructure.7
Nirav R Bhakta, MD, PhD, a pulmonologist and critical care specialist at the University of California, San Francisco, and a contributor to American Thoracic Society guidance on pulmonary function testing, underscored the broader implications of that shift.
“In many areas of the world, the categorization of people by race is associated with structural racism and its negative effects,” Dr Bhakta said in the Society’s statement. “Globally, race/ethnicity is a social construct that changes across geography and time, making it difficult to envision it as a fixed characteristic of people; this is true now more than ever before with increased movement of people and mixing of cultures.”7
The American Lung Association has also highlighted persistent disparities in asthma diagnosis and treatment, citing delayed disease recognition and undertreatment alongside environmental and structural factors as primary drivers.8
Why Change Has Been Slow
Despite growing evidence and clear guidance from professional societies, race-neutral reference equations for pulmonary function testing are still not widely used in clinical practice.7 Dr Rutland does not see that as resistance so much as inertia.
According to Dr Rutland, spirometry interpretation is not something most clinicians consciously recalibrate. It is often embedded in vendor platforms and laboratory reporting systems, meaning that changing reference equations may require institutional-level decisions and updates to software — not simply an individual clinician choosing a different option.
“These equations are everywhere,” he says. “Most clinicians aren’t choosing them — they’re inheriting them.” He also notes part of the issue is more subtle: “People trust the numbers — they don’t always realize how much judgment went into creating them.”
Moreover, who enters pulmonary medicine — and who feels represented there — also influences how quickly long-standing assumptions are examined, Dr Rutland says.
Black physicians remain underrepresented in pulmonary and critical care medicine, reflecting broader disparities across internal medicine subspecialties. According to data from the Association of American Medical Colleges, Black physicians comprise roughly 5% of the US physician workforce overall, with lower representation in many subspecialty fields.9
Dr Rutland traces his own path back to visibility. Growing up in Northern California, his pediatrician was a Black physician.
“That’s when I knew I could do this,” he says. “I could see myself in it.”
Representation shapes more than career choices, he says. It shapes trust, communication, and who has their concerns heard. “People go where they can imagine themselves,” he says, adding, “that matters in medicine, too.”
What This Means in Clinical Practice — Beyond Spirometry
Pulmonary function testing is only one piece of the larger picture, Dr Rutland stresses.
Spirometry influences how disease is recognized and classified. However, clinical outcomes are also shaped by environmental exposure, access to care, medication affordability, and the realities of patients’ daily lives — factors that disproportionately affect Black communities and accumulate over time, he says.
Dr Rutland urges clinicians to look beyond what is captured on intake forms and understand the context of where patients live.
“An address doesn’t tell you what someone is breathing,” he says. “You have to understand the neighborhood. Are diesel trucks cutting through the neighborhood? Are there ongoing sources of pollution nearby? Those exposures matter, and they add up.”
Access to care presents another challenge. Dr Rutland notes that missed appointments or delays in follow-up care are often seen as disengagement when they may instead result from work schedules, transportation issues, or caregiving duties.
“If someone misses a visit, ask why,” he says. “Don’t assume they didn’t care.”
Medication access can be just as decisive. In asthma care, escalation often depends on inhalers patients never receive — not because they refused them but because cost or insurance coverage created a barrier. Dr Rutland encourages clinicians to confirm that prescriptions are filled and to ask patients directly about barriers to care.
“If the patient can’t get the inhaler, the plan you made doesn’t exist.”
And when spirometry results do not match the larger clinical picture, he advises caution over reassurance.
“If a patient is telling you they can’t breathe, believe them,” he says. “Don’t let one test override everything else.”
