Just-in-Time Adaptive Interventions (JITAI) to Improve Indoor Air Quality in Sleep Environments: A Pilot Study

Abstract: Just-in-Time Adaptive Interventions (JITAIs) are used in mobile health to support self-management by delivering timely and personalized assistance. However, their effectiveness in prompting occupants to adjust their physical environment to improve indoor air quality (IAQ) remains unclear. As a pilot of a large-scale field campaign, we developed a smartwatch-based JITAI that nudges occupants toward IAQ-improving behaviors. Its effectiveness was evaluated through a micro-randomized field trial in Singapore (n = 12), with each participant completing 60 valid study days. The results show that ~90% of participants perceived the JITAI as helpful. Indicative window-opening events, used as a proxy for behavioral responses to JITAI prompts, were ~2.6 times more frequent on days with JITAI than without (15.8% vs. 6.2%), but the recommended 20-minute ventilation period was insufficient to improve IAQ. Future studies should improve the JITAI message content and incorporate feedback mechanisms that help users recognize the positive effects of their actions.

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