“The city isn’t uploading me to TikTok”: Exploring Privacy Attitudes towards Data Collection in Urban Public Spaces
Authors: Julian Todt (Karlsruhe Institute of Technology), Emiram Kablo (Paderborn University), Felix Morsbach (Karlsruhe Institute of Technology), Patricia Arias-Cabarcos (European Commission, Joint Research Centre (JRC)), Thorsten Strufe (Karlsruhe Institute of Technology)
Volume: 2026
Issue: 4
Pages: 7–35
DOI: https://doi.org/10.56553/popets-2026-0108
Abstract: Smart cities promise safer streets, smoother traffic, and more efficient services, enabled by dense networks of urban sensors. Yet this infrastructure, often unnoticed by citizens, introduces pervasive privacy risks, from tracking, profiling, and sensitive inferences to subtle forms of self-censorship. Despite widespread deployment, little is known about how the public understands and perceives these sensing systems. To address this gap, we present an intervention based user study (n = 172) in which participants are exposed to data collection by six urban sensors, including cameras and alternative technologies commonly framed as privacy-preserving. Participants encounter either the sensors alone or sensors accompanied by real-time data visualizations. Our results reveal widespread misunderstanding of some sensors (radar, LiDAR, Wi-Fi, depth, and thermal imaging sensors), particularly their capacity for identification and for attribute inferences such as gender or age. We also identify persistent misconceptions, including the belief that Wi-Fi poses privacy risks only when users connect to public networks. While making sensors visible and visualizing collected data improves privacy awareness, these measures alone are not enough for citizens to understand the actual risks of urban sensing. We derive recommendations for privacy-respecting smart city environments grounded in citizens’ informational needs and expectations.
Keywords: privacy, transparency, sensors, smart city, user study
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