A pilot study found that wearable devices and GPS tracking can reveal real-time health effects from heat and air pollution, opening new possibilities for personalized environmental health monitoring.
As climate change increases the frequency of extreme heat and worsens air pollution, scientists are looking for better ways to measure how these conditions affect people in real time. A new pilot study from researchers at The City University of New York found that combining wearable devices, smartphone location tracking, and real-time surveys can successfully monitor environmental exposures along with their immediate physical and emotional effects.
The study was published in JMIR Formative Research. Authors included Sameera Ramjan and Melissa Blum as co-first authors, along with Rung Yu Tseng, Katherine Davey, Duke Shereen, and senior author Yoko Nomura.
“People move through many different environments each day, and this approach lets us capture that in real time,” said Ramjan, a doctoral student in the CUNY Graduate Center Psychology program. “We were struck by how quickly the data revealed patterns—changes in heart rate variability, shifts in mood—that lined up with where participants had been and what they were exposed to.”
Wearable Devices Reveal Health and Mood Patterns
Participants in the study wore Fitbit smartwatches for about a month and completed short mood surveys called ecological momentary assessments several times each day. Researchers combined those responses with smartphone GPS data to estimate exposure to heat and pollutants, including nitrogen dioxide, particulate matter, and sulfur dioxide, based on participants’ daily movements.
Results showed the method was both practical and informative. Higher exposure to heat and nitrogen dioxide was linked to changes in heart rate variability, which reflects the body’s ability to recover from stress. Increased sulfur dioxide exposure was associated with stronger feelings of nervousness and hopelessness.
Researchers also found that greater heat exposure corresponded with lower self-reported sadness, a surprising result that may be connected to increased outdoor activity and social interaction during warmer weather. The team noted that larger studies are needed to better understand these findings.
“Even in a small pilot, we could see that the relationship between environmental conditions and people’s physiological and emotional responses is more complex than traditional methods can capture,” said Blum, a medical student at the Icahn School of Medicine at Mount Sinai. “By combining wearable sensors, GPS data, and real-time surveys, we’re able to build individualized exposure profiles that move with people throughout their day. That’s a real shift from relying on stationary monitors or home addresses.”
First Study Combining GPS, Wearables, and Surveys
“To our knowledge, this is the first study to combine wearable devices, ecological momentary assessment, and continuous GPS tracking to measure environmental exposures and their immediate health impacts,” said senior author Nomura, a distinguished professor of psychology at the CUNY Graduate Center and Queens College with an appointment at the Icahn School of Medicine at Mount Sinai. “It’s a small pilot, but it demonstrates an integration between consumer technology and environmental epidemiology that could open the door to personalized approaches for preventive medicine.”
Researchers also identified ways to improve the system, including making it easier to use and increasing participant adherence. Those adjustments have already been incorporated into the next phase of the project. Nomura’s team is now using the updated system in a larger National Institutes of Health (NIH)-supported study focused on how prenatal and current environmental exposures influence adolescent brain development and mental health.
The research arrives as extreme heat and air pollution continue to rise, especially affecting vulnerable groups such as children, pregnant people, individuals experiencing homelessness, and people with lower socioeconomic status. Children may face greater long-term risks because environmental exposures can influence brain development and behavior.
Potential Public Health and Clinical Applications
Beyond research, the technology could eventually support clinical care. Real-time monitoring of environmental exposure may help doctors make better decisions for patients whose conditions are affected by heat or poor air quality.
“This is still early-stage work, and we’re cautious about reading too much into a small sample,” Nomura said. “But improving how we measure exposure is a critical step toward protecting public health, and these results give us confidence that the approach can scale.”
Reference: “Feasibility of Integrating Wearable Devices and Ecological Momentary Assessment for Real-Time Environmental Exposure Estimation: Proof-of-Concept Study” by Sameera Ramjan, Melissa Blum, Rung-Yu Tseng, Katherine Davey, Ahmed Duke Shereen and Yoko Nomura, 8 May 2026, JMIR Formative Research.
DOI: 10.2196/86615
The study was supported by a Professional Staff Congress–City University of New York (PSC-CUNY) research grant.
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