Meteorological Condition Forecast Of Heatstroke Based On Human-Environment Heat Balance Model

Exposure to extreme hot weather is associated with increased morbidity and mortality compared with an intermediate, comfortable temperature range. Global warming and heat island effect are expected to increase average summer temperatures and the frequency and intensity of hot days. But the study of heat-waves and warning system in China is deficient, meteorological condition forecast of heatstroke based on human-environment heat balance model was developed to save lives in our paper.Almost heat-health warning systems use absolute maximum temperature values, or number of days above a given threshold, but the thermal regulation and thermal comfort of human body can not be assessed only by air temperature or other simple indexes and heat-waves timing within the summer season significantly effect deaths caused by heatstroke. The only way to describe the effects of the thermal environment on human body completely is using a heat balance model. The physiological equivalent temperature (PET) based on heat balance model and relatively threshold ware used in our method to predict the meteorological conditions of heatstroke. The relatively threshold includes two parts: short-term threshold, and long-term threshold. At first, in order to study the effect of meteorological parameters on human comfort, sensitivity test was executed, and reasonable improvement of heat balance model was introduced. Then, a set of meteorological data (temperature, cloud, wind velocity, relative humidity) between 1955 and 2005 from 31 cities was used to analyze the distribution of heat stress in China. Last, the daily data of mortality of all causes in summer (15 June-15 September) was collected to analyze the condition of heatstroke in Shanghai. Based on heat balance model and relatively threshold, the method of meteorological condition forecast of heatstroke was developed, and a comparison between heat balance method and torridity index technique commended by CMA was made to analyze the efficiency of new method.The results show that:(1) PET shows a linear growth under increase of temperature and mean radiant temperature, there is a non-linear decreasing relationship between PET and wind velocity, relative humidity can increase PET evidently in hot environment. (2) Annual average PET of main 31 capital cities in China rose by about 1.7°C for the last 50 years, with a changing rate about 0.35°C/10a. The changing rate of PET is larger than the warming rate of temperature in China. (3) Extreme hot days were increasing in main capital cities. (4) Nanchang, Chongqing, Wuhan, Changsha, Sian, Fuzhou, Hangzhou and Shanghai are easy to be attacked by extreme hot days and sustained extreme hot days taken as heat-wave. (5)The score of heatstroke meteorological condition forecasting method in our evaluating system in Shanghai is 62.4 in the first grade, 72.3 in the second grade, 71.6 in the third grade, 80.0 in the fourthly grade, and forecasting efficiency of new method excel the torridity index technique evidently.Now, the study of heat stress in Chinese big cities is few by human-environment heat balance model. Our results indicate that heat-waves occur frequently in some cities. More heat-waves warning systems need to be implemented in interrelated cities, and our new heat-balance method is finer choice.