Evaporation May Explain Breath Test Variability
Researchers say the finding could eventually help make breath-based lung tests more consistent for patients in South Bend and beyond.
Updated on Nov. 2, 2026 in Asthma
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Notre Dame researchers led by Jingcheng Ma found that evaporation can cause exhaled breath condensate (EBC) droplets to lose significant biomarker content within a single breath cycle, a possible reason EBC measurements have been inconsistent. The findings, published in Nano Letters, point toward more reliable breath-based testing for lung conditions such as COPD, a condition that is the third leading cause of death worldwide.
Why it matters
Breath tests that collect EBC are affordable and portable, but repeated measurements have been hard to trust, which has limited their use in clinics. Identifying evaporation as a driver of biomarker loss suggests the variability may be physical rather than only biological, opening a path toward standardizing these tests for lung disease monitoring.
The study used mathematical modeling of single droplets combined with the lab's home-built fluorescence platform to visualize droplet-level transport. The findings are laboratory-based and preliminary, and have not yet been tested in clinical populations.
The players
University of Notre Dame
A private research university in South Bend, Indiana, with active research programs in nanotechnology and precision health.
Berthiaume Institute for Precision Health
A Notre Dame institute that funds research aimed at personalized and precision approaches to human health.
The details
When a person exhales into a collection device, the breath condenses into tiny droplets that are cooled and collected for analysis. The Notre Dame team found that as these droplets sit, they can lose biomarkers through evaporation, with the amount lost depending on droplet size and on how long the breather pauses between breaths. By tracking biomarker losses during condensation and evaporation, the researchers built a model that explains why measurements from the same person can differ.
Timeline
October 7, 2026: Research led by Ma's group was published in Nano Letters and announced by the Notre Dame news office.
November 2, 2026: A news article about the findings was published on news.nd.edu.
Health Landscape
Breath-based testing has long been considered a low-cost way to monitor airway and lung disease, but inconsistent measurements have kept it from routine clinical use. This work shifts the explanation from biological variation alone toward gas-liquid phase transition, which may open a route to standardized breath tests.
If you manage a lung condition such as COPD or asthma, this research may eventually lead to more consistent breath-based tests, which could help track changes over time. For now, breath tests are not a substitute for standard clinical evaluation, so any questions about monitoring should be raised with your doctor.
The takeaway
Breath-based tests are promising, but results may vary from one sample to the next for reasons unrelated to the person's health. If you are considering a breath test or have questions about lung disease monitoring, discuss them with your physician.
Further reading
For the broader context on breathing-related conditions, explore our Asthma coverage.
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