Institute of Space and Earth Information Science, The Chinese University of Hong Kong, Hong Kong Special Administrative Region of China.
Institute of Space and Earth Information Science, The Chinese University of Hong Kong, Hong Kong Special Administrative Region of China; Department of Geography and Resource Management, The Chinese University of Hong Kong, Hong Kong Special Administrative Region of China.
Soc Sci Med. 2024 Dec;363:117411. doi: 10.1016/j.socscimed.2024.117411. Epub 2024 Oct 20.
Mental stress issues are emerging among residents of modern cities. Among environmental factors associated with stress mitigation, greenspace has consistently been shown to have significant stress-reducing properties. However, the temporality of greenspace exposure, particularly the cumulative threshold effect in urban environments, has been largely neglected in past studies. In addition, different algorithms and their related measurements of greenspace have led to inconsistent mental health outcomes. To address both gaps, we evaluated the dynamic greenspace exposure of 221 Hong Kong residents by integrating three distinct green space measurements: the Normalized Difference Vegetation Index (NDVI), the Green Space Area Ratio (GSAR), and the Eye-level Green View Index (GVI) based on individual real-time GPS data. We subsequently gauged individual momentary stress levels via Ecological Momentary Assessment (EMA) and modeled its association with dynamic green space exposure using mixed ordinal logistic regression across diverse cumulative time frames. The results reveal great disparities in greenspace-stress association between different greenspace measurements and different cumulative time frames: (1) Among the three measurements, GVI is the most robust and effective measurement in assessing the stress-reducing effect in urban environments. (2) Within specific time frames, cumulative exposure has a more pronounced stress-reducing influence than momentary exposure. (3) The stress-reducing effects of cumulative eye-level greenspace exposure exhibit two temporal phases: A continuous exposure spanning 12-36 min leads to a progressive enhancement in the stress-mitigating effect of eye-level greenspace, peaking initially and then diminishing after 36 min. Upon extended exposure reaching 2.3 h, the stress-alleviating impact of eye-level green space peaks once again before gradually waning. Our research underscores the need for multiple measurements of environmental exposure to address the algorithmic uncertainty in environmental health research and deeper insights into the temporality of the greenspace-mental relationship.
精神压力问题在现代城市居民中日益显现。在与减轻压力相关的环境因素中，绿地一直被证明具有显著的减压特性。然而，过去的研究在很大程度上忽略了绿地暴露的时间性，特别是城市环境中的累积阈值效应。此外，不同的算法及其相关的绿地测量方法导致了不一致的心理健康结果。为了解决这两个差距，我们通过整合三种不同的绿地测量方法，即归一化植被指数（NDVI）、绿地面积比（GSAR）和基于个体实时 GPS 数据的平视绿色视野指数（GVI），评估了 221 名香港居民的动态绿地暴露情况。我们随后通过生态瞬时评估（EMA）来衡量个体的即时压力水平，并通过混合有序逻辑回归模型来衡量其与不同累积时间框架下动态绿地暴露的关联。结果表明，不同的绿地测量方法和不同的累积时间框架之间存在巨大的绿地与压力关联差异：（1）在这三种测量方法中，GVI 是评估城市环境减压效果最稳健和有效的测量方法。（2）在特定时间框架内，累积暴露比瞬时暴露具有更显著的减压影响。（3）累积平视绿地暴露的减压效果呈现两个时间阶段：持续暴露 12-36 分钟可使平视绿地的减压效果逐渐增强，初始时增强幅度较大，36 分钟后逐渐减弱。当暴露时间延长至 2.3 小时时，平视绿色空间的缓解压力效果再次达到峰值，然后逐渐减弱。我们的研究强调需要对环境暴露进行多种测量，以解决环境健康研究中算法不确定性的问题，并深入了解绿地与心理健康关系的时间性。
