Lin Guo-Shiuan, Llaguno-Munitxa Maider, Manoli Gabriele
Laboratory of Urban and Environmental Systems, School of Architecture, Civil and Environmental Engineering, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland.
Louvain Research Institute of Landscape, Architecture, Built Environment, Université Catholique de Louvain (UCLouvain), Ottignies-Louvain-la-Neuve, Belgium.
PLoS One. 2025 Sep 3;20(9):e0330912. doi: 10.1371/journal.pone.0330912. eCollection 2025.
Extreme temperatures pose a serious threat to human health, especially in urban areas where the majority of the world population is living. Temperature-related risks are exacerbated by urban-induced warming but existing exposure assessments rely on a static residential population, thus overlooking space-time changes in population density and their covariation with urban temperatures. Here we combine 1-km monthly daytime and nighttime population estimates for 80 European cities with existing high-resolution urban climate simulations to quantify the impact of daily and seasonal mobility on residents' exposure to heat and cold. Using city-specific exposure-response curves and the respective minimum mortality temperatures as thresholds to define hazardous conditions we calculated that, on daily timescales, commuting towards city centers causes a 7.8% average increase (IQR:1.0-12.9%) in summer heat exposure but, during winter, it provides a slight protective effect against cold. On seasonal timescales, changes in total population are out of phase with the temperature cycle in most European cities, leading to a lower exposure to heat, with the exception of touristic destinations where exposure increases, on average, by 0.9% during the warmest months. These results highlight the key role of human mobility for heat risk assessment and adaptation and they reveal the existence of general exposure trends that hold across diverse cities and climates.
极端温度对人类健康构成严重威胁，尤其是在世界上大多数人口居住的城市地区。城市导致的气候变暖加剧了与温度相关的风险，但现有的暴露评估依赖于静态的常住人口，从而忽视了人口密度的时空变化及其与城市温度的协变关系。在此，我们将80个欧洲城市每月1公里分辨率的白天和夜间人口估计数据与现有的高分辨率城市气候模拟相结合，以量化日常和季节性流动对居民暴露于高温和低温的影响。利用特定城市的暴露-反应曲线以及各自的最低死亡率温度作为定义危险条件的阈值，我们计算得出，在每日时间尺度上，通勤前往市中心会导致夏季热暴露平均增加7.8%（四分位距：1.0-12.9%），但在冬季，这会对寒冷起到轻微的防护作用。在季节时间尺度上，大多数欧洲城市的总人口变化与温度周期不同步，导致热暴露降低，但旅游目的地除外，在最温暖的月份，这些地方的热暴露平均增加0.9%。这些结果凸显了人口流动在热风险评估和适应中的关键作用，并揭示了在不同城市和气候条件下普遍存在的暴露趋势。
