So Chu Wing, Pun Chun Shing Jason, Liu Shengjie, Cheung Sze Leung, Hui Ho Keung Kenneith, Blumenthal Kelly, Walker Constance Elaine
Department of Physics, The University of Hong Kong, Pokfulam, Hong Kong, China.
Spatial Sciences Institute, University of Southern California, Los Angeles, 90089, CA, USA.
Sci Rep. 2025 Jul 1;15(1):21414. doi: 10.1038/s41598-025-05279-4.
Light pollution, a typically underrecognized environmental issue, has gained attention in recent years. While controlling light pollution requires sustained efforts, Earth Hour offers a unique natural experimental setting to assess temporary lights-out measures. Using photometric and spectroscopic sensors, we observed up to 50% night sky darkening during Earth Hour from 2011 to 2024 in Hong Kong, primarily as a result of a small but critical number of lights-out instances in central business districts, as evidenced by crowd-sourced photography records. Weekend lighting pattern in the city during Earth Hour remained unaffected. The emission reductions mostly occurred in the 445-500, 500-540, and 615-650 nm spectral ranges-corresponding to peak emissions from LED billboard screens- and in the 585-595 nm range, associated with metal halide floodlights used for facades and billboards. Our study identifies these sources as major contributors to urban light pollution. By combining multimodal observations, we offer a comprehensive assessment of light pollution sources and the potential benefits of sustainable lighting practices in urban environments. This research highlights the importance of targeted light pollution mitigation efforts and provides critical insights for policymakers to enhance urban sustainability and human well-being.
光污染是一个典型的未得到充分认识的环境问题，近年来已受到关注。虽然控制光污染需要持续努力，但“地球一小时”提供了一个独特的自然实验环境来评估临时熄灯措施。我们使用光度和光谱传感器，在2011年至2024年期间观察到香港在“地球一小时”期间夜空亮度下降了50%，这主要是由于中央商务区少量但关键的熄灯情况所致，众包摄影记录证明了这一点。“地球一小时”期间城市的周末照明模式未受影响。排放减少主要发生在445 - 500、500 - 540和615 - 650纳米光谱范围内（对应于LED广告牌屏幕的峰值排放）以及585 - 595纳米范围内（与用于外墙和广告牌的金属卤化物泛光灯有关）。我们的研究确定这些来源是城市光污染的主要贡献者。通过结合多模态观测，我们对城市环境中的光污染源以及可持续照明实践的潜在益处进行了全面评估。这项研究强调了有针对性的光污染缓解措施的重要性，并为政策制定者提高城市可持续性和人类福祉提供了关键见解。
