Department of Geography, Ryerson University, Toronto, ON, Canada, M5B 2K3.
Environ Monit Assess. 2012 Dec;184(12):7329-42. doi: 10.1007/s10661-011-2502-z. Epub 2012 Jan 19.
The public health consequences of extreme heat events are felt most intensely in metropolitan areas where population density is high and the presence of the urban heat island phenomenon exacerbates the potential for prolonged exposure. This research develops an approach to map potential heat stress on humans by combining temperature and relative humidity into an index of apparent temperature. We use ordinary kriging to generate hourly prediction maps describing apparent temperature across the Greater Toronto Area, Canada. Meteorological data were obtained from 65 locations for 6 days in 2008 when extreme heat alerts were issued for the City of Toronto. Apparent temperature and exposure duration were integrated in a single metric, humidex degree hours (HDH), and mapped. The results show a significant difference in apparent temperature between built and natural locations from 3 PM to 7 AM; this discrepancy was greatest at 12 AM where built locations had a mean of 2.8 index values larger, t(71) = 5.379, p < 0.001. Spatial trends in exposure to heat stress (apparent temperature, ≥ 30°C) show the downtown core of the City of Toronto and much of Mississauga (west of Toronto) as likely to experience hazardous levels of prolonged heat and humidity (HDH ≥ 72) during a heat alert. We recommend that public health officials use apparent temperature and exposure duration to develop spatially explicit heat vulnerability assessment tools; HDH is one approach that unites these risk factors into a single metric.
极端高温事件对公共健康造成的影响在人口密度高且存在城市热岛现象的大都市地区最为强烈，因为这些地区人们面临长时间暴露在高温环境下的潜在风险。本研究通过将温度和相对湿度结合成一个表观温度指数，开发了一种方法来绘制人类潜在热应激的地图。我们使用普通克里金法生成了描述加拿大大多伦多地区每小时表观温度的预测图。气象数据来自 2008 年 6 天的 65 个地点，当时多伦多市发布了极端高温警报。将表观温度和暴露持续时间整合到一个单一指标——湿热指数小时数（HDH）中，并进行了绘制。结果表明，在 3 时至 7 时之间，建筑区域和自然区域的表观温度存在显著差异；这种差异在 12 时最大，建筑区域的平均表观温度大 2.8 个指数值，t(71)=5.379，p<0.001。暴露在热应激（表观温度≥30°C）中的空间趋势显示，多伦多市市中心和大多伦多地区的密西沙加（多伦多以西）大部分地区在高温警报期间可能会经历长时间的高温高湿（HDH≥72）的危险水平。我们建议公共卫生官员使用表观温度和暴露持续时间来开发具有空间特异性的热脆弱性评估工具；HDH 是将这些风险因素统一到一个单一指标的一种方法。
