Influence of extreme temperatures on respiratory, circulatory, and nonaccidental mortality risks in northeast China

Epidemiological research indicates that extreme temperatures represent a major hazard to public health. In this study, daily data of climatic parameters, air pollutants, and the number of circulatory, respiratory, and nonaccidental death were collected from capital cities in northeast China from 2014 to 2016. A distributed lag nonlinear model was used to determine the impact of extreme temperatures on mortality risks. The results indicate that both low and high extreme temperatures pronounced the peaks on respiratory mortality. The heat effect changed rapidly and forcefully with a short lag (3-5 days); whereas, the cold effect gradually increased with a considerably longer lag (>14 days). The mortality risk revealed the greatest in Shenyang, for which the circulatory risk was highest in warm days, with a relative risk (RR) of 1.045, and the respiratory risk was highest in warm nights (RR = 1.050). These findings have a valuable reference for efforts to health protection in China.