Influence of daily average temperature on the risk of resident mortality in Zhenjiang, China: an assessment based on a distributed lag nonlinear model

Objective To investigate the relationship between daily average temperature and the daily mortality of residents in Zhenjiang, China.

Methods A distributed lag nonlinear model was performed to fit data of daily mortality, meteorology and air pollution in Zhenjiang from 2015 to 2021, so as to analyze the lag and cumulative effects of daily average temperature on daily mortality.

Results A U-shaped relationship was observed between daily average temperature and daily mortality. The thermal effects of high temperature were acute short-term, and reached the highest at lag 0 d for total non-accidental, cardiovascular and respiratory mortalities, with risk ratio(RR) values of 1.19(95% confidence interval CI: 1.13-1.25), 1.46(95%CI: 1.32-1.61) and 1.59(95%CI: 1.27-2.00), respectively. On the other hand, there was a lag effect of cold temperature on mortality, which lasted until the 11th day for total non-accidental and cardiovascular mortalities, with maximum RR values of 1.08(95%CI: 1.05-1.10) and 1.07(95%CI: 1.02-1.11), respectively. The cumulative cold effects of low temperature on total non-accidental and cardiovascular mortalities reached their maximum at lag 30 d and lag 20 d, respectively, while the cumulative thermal effects of high temperature on total non-accidental, cardiovascular, and respiratory mortalities all reached their maximum at lag 3 d.

Conclusion Exposure to high or low temperature is significantly associated with increased risk of resident mortality in Zhenjiang, and there is a lag effect.