Interaction effects between ambient temperature and PM2.5 and O3 on mortality in Chengdu

Daily death data of respiratory and cardiovascular diseases during 2014~2016, meteorological data and daily average particulate matter with aerodynamic less than 2.5 (PM2.5) and daily ozone 8h maximum concentration (O3) during the same time period in Chengdu were collected. Distributed Lag Non-linear Model (DLNM) and three semi-parametric Generalized Additive Models (GAMs), including an independent model, a nonparametric bivariate response surface model, and a stratification parametric model, were adopted to explore the adverse health effects of temperature, air pollutants (PM2.5 and O3) and the synergistic effects between temperature and PM2.5 (or O3) on respiratory and cardiovascular system diseases, respectively. The results of single-effect studies showed that the exposure-response relationships between ambient temperature and respiratory and cardiovascular diseases both exhibited inverse J type and the most comfortable temperature were 22.2℃, which corresponding to the least mortality. The health risks were strongest between the current and previous day (lag01) average concentrations of PM2.5 and O3. Per 10µg/m3 increment in PM2.5 and O3 were associated with 0.58% and 0.54% increase in respiratory mortality and 0.35% and 0.66% increases in cardiovascular mortality, respectively. The combined effects between the temperature and different air pollutant on human health suggested that the mortality reach the maximum when high temperature and high mass concentrations of PM2.5 (or O3) coexisted. Furthermore, the results of seasonal study showed that PM2.5 had the highest health risk on mortality in winter and O3 had the most significant health risk in autumn. Furthermore, the results of interaction study showed that there was a synergistic amplification effect between high temperature and high concentration of PM2.5 (or O3) on mortality. Under high temperature, per 10µg/m3 increment in PM2.5 and O3 were associated with 2.30% and 1.14% increase in respiratory mortality and 1.09% and 1.03% increases in cardiovascular mortality, respectively. We should also pay more attention to the adverse effect of O3 on human health in the future. © 2021, Editorial Board of China Environmental Science. All right reserved.