This protocol paper describes a prospective observational study using GPS devices and wrist-worn biosensors to investigate minute-level associations between environmental exposures (green-blue space, walkability, air pollution) and stress-related biomarkers in 750 Hong Kong participants over 2024-2026.
Key Findings
Results
The pilot study achieved a high completion rate and strong device compliance among the first 150 participants.
150 participants completed the pilot study as of June 30, 2025 (September 2024 onwards)
Overall completion rate was 94% (141/150)
Valid biosensor days rate was 94% (141/150)
Daily questionnaire compliance was 91% (137/150)
Methods
The study protocol includes a 1-week experiment design with multiple simultaneous data collection methods.
Participants wear biosensors and carry GPS devices for one week
Participants complete daily surveys and entry and exit questionnaires
Primary outcomes include digital biomarkers: electrodermal activity, blood volume pulse, and skin temperature from wrist-worn sensors
Secondary outcomes include accelerometer-based physical activity metrics and environmental exposure assessments including mobility barriers, land use mix, road accessibility, and thermal conditions
Methods
The full study targets 750 participants aged 18-80 years in Hong Kong with data collection running from September 2024 to December 2026.
Recruitment spans September 2024 to December 2026
The pilot study was supported by internal funds starting September 2024
External funding from the Health and Medical Research Fund by the Hong Kong Health Bureau commenced in July 2025
As of September 2025, 30 participants were enrolled in the main study
Data analysis is expected to be completed by June 2027, with results anticipated for publication in 2027 and 2028
Methods
Primary environmental exposures of interest include air pollution, urban density, and green-blue space access, assessed at the minute level using GPS-based measurements.
Traditional methods have limitations in capturing dynamic environmental exposure effects on mental health
The study uses GPS-based measurements to capture minute-level environmental exposure
Secondary environmental exposure assessments include mobility barriers, land use mix, road accessibility, and thermal conditions
Focus groups were conducted to refine the study protocol and assess device-wearing experience
Results
Protocol refinements were implemented based on participant feedback from the pilot study without altering core instruments.
Feedback was collected through focus groups to refine study protocol and assess device-wearing experience
Core instruments remained unchanged following protocol refinements
The study received ethical approval from the Human Ethics Research Committee with award numbers EA240125 and EA240514
The study is at an early stage of data cleaning and preprocessing for the pilot study as of June 2025
Cao Y, Li T, Tribby C, Chang D. (2026). Environmental Exposure and Mental Health in Hong Kong: Protocol for a GPS- and Biosensor-Based Observational Study.. JMIR research protocols. https://doi.org/10.2196/84919