The emergence of urban heat traps and human mobility in 20 US cities

Understanding the relationship between spatial structures of cities and environmental hazard exposures is essential for urban health and sustainability planning. However, a critical knowledge gap exists regarding the extent to which socio-spatial networks shaped by human mobility exacerbate or alleviate urban heat exposures. This study utilizes anonymized location-based data to construct human mobility networks in twenty U.S. metropolitan areas and analyzes them alongside urban heat characteristics. We identify high- and low-heat exposure areas and evaluate visitation patterns of populations residing in these areas to other areas with similar or dissimilar heat exposure. The results reveal the presence of urban heat traps in most metropolitan areas, wherein populations in high-heat exposure areas primarily visit other high-heat zones; Los Angeles, Boston, and Chicago are particularly pronounced. We also observe smaller proportions of mobility-driven heat escalation and heat escapes. The findings enhance understanding of mobility-mediated urban heat exposure and inform integrated urban design and planning to promote health and sustainability.