Gulbali Institute, Charles Sturt University, Albury, NSW 2640, Australia.
Int J Environ Res Public Health. 2023 Aug 5;20(15):6531. doi: 10.3390/ijerph20156531.
While shade and air flow are recognised factors that reduce outdoor heat exposure, the level of reduction in terms of labour capacity at varying air temperature and humidity levels is poorly understood. This study investigated cooling effects on the commonly used heat index, wet bulb globe temperature (WBGT), and subsequent impact on labour capacity, for a range of air flow and shade conditions in warm to hot climates. We modelled heat exposure using a physics-based method to map WBGT for a case study region which experiences a range of heat categories with varying levels of health risks for outdoor workers. Continent-scale modelling confirmed significant spatial variability in the effect of various shade and wind speed scenarios across a range of real-world mid-summer daytime conditions. At high WBGTs, increasing shade or air flow for outdoor workers lowered heat exposure and increases labour capacity, with shade giving the greatest benefit, but cooling varied considerably depending upon underlying air temperature and humidity. Shade had the greater cooling effect; reducing incident radiation by 90% decreased WBGT by 2-6 °C depending on location. Wind had a lower cooling effect in the hottest regions, with a decreasing exponential relationship between wind speed and WBGT observed.
虽然遮阳和空气流通被认为是降低户外热暴露的因素，但在不同空气温度和湿度水平下，其降低劳动能力的程度还了解甚少。本研究调查了在温暖到炎热气候下，不同空气流动和遮阳条件下对常用热指数湿球黑球温度 (WBGT) 的冷却效果及其对劳动能力的后续影响。我们使用基于物理的方法来模拟热暴露，为案例研究区域绘制 WBGT，该区域经历了一系列不同健康风险水平的热类别，涉及户外工作者。大陆范围的建模证实，在各种真实世界的夏季白天条件下，各种遮阳和风速场景的影响在空间上存在显著的可变性。在高温 WBGT 下，增加户外工作者的遮阳或空气流通会降低热暴露并提高劳动能力，遮阳的效果最大，但冷却效果因基础空气温度和湿度的不同而有很大差异。遮阳具有更大的冷却效果；根据地点的不同，减少 90%的入射辐射可使 WBGT 降低 2-6°C。在最热的地区，风的冷却效果较低，观察到风速与 WBGT 之间呈负指数关系。
