Nighttime Light Color Characteristics and Blue Light Exposure in China based on SDGSAT-1 Glimmer Image

In the 1860s, humanity entered the electrical era, characterized by the widespread use of artificial light. This development created conditions for nighttime social and economic activities, significantly expanding the temporal and spatial range of human engagement and fostering the growth of a vibrant nighttime economy, which has become an important indicator of urban vitality in modern society. However, the rise of artificial lighting also increases risks to human health and the environment. Research highlights that blue light, a high-energy segment of the visible spectrum emitted by artificial light sources, is particularly concerning. Studies have linked blue light exposure to skin cancer, retinal damage, and increased melanin production, leading to various health complications. Although significant advancements in remote sensing technology support research on nighttime light, studies specifically examining human exposure to blue light are still limited. The main reason is the constraints of available multispectral nighttime light images. In this study, we leverage the latest open-source multispectral nighttime glimmer image obtained from the SDGSAT-1 to create a 40-meter resolution RGB nighttime light products for China. We then focus on extracting the blue light component and analyze its spatial characteristics in relation to human exposure. We uncover several key findings: 1) Overall, blue light exposure in China exhibits a dispersed distribution of high-value areas, with notable local concentrations. 2) In urban regions, new urban developing areas have higher blue light exposure compared to older areas, and commercial areas have higher exposure level than residential and industrial areas. 3) In China, the Greater Bay Area (GBA) stands out with exceptionally high blue light exposure relative to other metropolitan regions.  This research enhances our understanding of the relationship between artificial light pollution and residents' living spaces. Furthermore, the findings provide valuable recommendations for urban planners and policymakers in developing protective measures and industry standards for nighttime light sources, ultimately contributing to sustainable urban development.