Smoking in campus public restrooms poses a persistent challenge due to the conflict between privacy protection and effective supervision. Traditional manual patrols are inefficient, while video surveillance violates privacy norms. This paper presents "Anonymous Guardian" — a lightweight, privacy-preserving reminder system based on Bluetooth low-energy perception and anonymous crowdsourcing. The system comprises an Arduino Uno controller, HC-05 Bluetooth module, ISD1820 voice playback unit, 18650 power module, and a WeChat mini-program. Students can anonymously trigger a pre-recorded voice reminder without direct confrontation or identity disclosure. A modular hardware design achieves unit cost below 200 RMB and supports rapid deployment in various campus scenarios. We design an RSSI-based distance verification algorithm with a moving average filter and an anti shake time-window mechanism to prevent malicious or repeated triggers. Experimental results demonstrate a Bluetooth connection success rate of 96.7% within 10 meters, average response delay of 0.8 seconds, and battery endurance of 52 hours. A four week pilot in two public restrooms at University of Science and Technology Liaoning (Library and Teaching Building E) shows user satisfaction of 86.2% (N=62) and a 62.5% reduction in smoking-related complaints. The system collects zero personally identifiable information, achieves high student acceptance, and provides a replicable paradigm for non invasive smoking intervention in privacy-sensitive spaces.

Li Zirong, Long Yanbin. Design and Optimization of a Campus Restroom Smoke-Free Anonymous Reminder System Based on Bluetooth Perception and Crowdsourcing Mechanism. Academic Journal of Engineering and Technology Science (2026), Vol. 9, Issue 3: 183-189. https://doi.org/10.25236/AJETS.2026.090324.

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