Interactive Effects Between Temperature and PM_(2.5) on Mortality:A Study of Varying Coefficient Distributed Lag Model-Guangzhou,Guangdong Province,China,2013-2020

Introduction:There is a large body of epidemiological evidence showing significantly increased mortality risks from air pollution and temperature.However,findings on the modification of the association between air pollution and mortality by temperature are mixed.Methods:We used a varying coefficient distributed lag model to assess the complex interplay between air temperature and PM_(2.5) on daily mortality in Guangzhou City from 2013 to 2020,with the aim of establishing the PM_(2.5)-mortality association at different temperatures and exploring synergetic mortality risks from PM_(2.5) and temperature on vulnerable populations.Results:We observed near-linear concentrationresponse associations between PM_(2.5) and mortality across different temperature levels.Each 10μg/m^(3)increase of PM_(2.5) in low,medium,and high temperature strata was associated with increments of 0.73%[95%confidence interval(CI):0.38%,1.09%],0.12%(95%CI:−0.27%,0.52%),and 0.46%(95%CI:0.11%,0.81%)in non-accidental mortality,with a statistically significant difference between low and medium temperatures(P=0.02).There were significant modification effects of PM_(2.5) by low temperature for cardiovascular mortality and among individuals 75 years or older.Conclusions:Low temperatures may exacerbate physiological responses to short-term PM_(2.5) exposure in Guangzhou,China.