Objective: To investigate the effect of hourly ambient temperature exposure on emergency calls in Xuchang city and Zhengzhou city. Methods: The hourly meteorological data, air pollution data and emergency calls of Xuchang city and Zhengzhou city were collected from January 1, 2017 to October 31, 2019. A distributed lag non-linear model was used to calculate the excess relative risk (ERR). The lag effect and cumulative effect of extreme temperature exposure on emergency calls were evaluated. Results: The relationship between hourly temperature exposure and emergency calls was a U-shaped curve. In Xuchang city and Zhengzhou city, both low and high temperatures would increase the number of hourly emergency calls. The earliest effect of low temperature occurred at a lag of 22 h and 52 h, with ERR values (95%CI) about 0.20% (0.00%, 0.39%) and 0.11% (0.00%, 0.22%), respectively. The earliest effect of high temperature occurred at a lag of 0 h with ERR values about 1.59% (1.09%, 2.09%) and 1.45% (1.22%, 1.69%), respectively. High temperature had the greatest impact on the number of emergency calls of cardiovascular disease at a lag of 4-8 h. The cumulative ERR values (95%CI) of the two cities were 8.70% (4.98%, 12.75%) and 3.89% (2.61%, 5.22%), respectively. Conclusion: High temperature exposure could increase the number of emergency calls within a few hours, while the effect of low temperature would not occur until 22 hours later.
目的： 探讨逐小时环境温度暴露对许昌和郑州市急救呼叫次数的影响。 方法： 收集许昌、郑州市2017年1月1日—2019年10月31日的逐小时气象资料、空气污染资料和急救呼叫数据，采用分布滞后非线性模型计算超额危险度（ERR），评估极端温度暴露对急救呼叫的滞后效应和累积效应。 结果： 逐小时温度暴露与急救呼叫次数呈“U”型关联。在许昌市和郑州市，低温和高温均会增加每小时急救呼叫次数。低温的最早影响出现在滞后22和52 h，ERR（95%CI）值分别为0.20%（0.00%，0.39%）和0.11%（0.00%，0.22%）；高温的最早影响均出现在滞后0 h，ERR（95%CI）值分别为1.59%（1.09%，2.09%）和1.45%（1.22%，1.69%）。高温在滞后4~8 h对心血管疾病的急救呼叫次数影响最大，许昌市、郑州市的累积ERR值（95%CI）分别为8.70%（4.98%，12.75%）和3.89%（2.61%，5.22%）。 结论： 高温暴露可在数小时内增加急救呼叫次数，而低温的影响在22 h后才会出现。.