Objective: To evaluate the influence of extreme ambient temperature on mortality and years of life lost (YLL) in Chongqing.
Methods: The daily mortality, meteorology and air pollution index data in Chongqing from the 1(st) January 2010 to the 31(st) December 2013 were collected. Distributed lag non-linear model (DLNM) was used to assess the influence of daily ambient temperature on daily number of deaths and daily YLL respectively. The delayed and cumulative effects of extreme temperature on sex, age, and cause-specific mortality were also assessed.
Results: The relationships between ambient temperature and non-accidental, cardiovascular disease and respiratory disease mortalities and YLL were U-shaped or W-shaped. The effect of heat was obvious on that day, peaked on day 7, and lasted for two weeks, whereas the effect of cold was obvious a week later and lasted for a month. As 1 ℃ increase of ambient temperature, the cumulative relative risks (CRR) of high temperature across lag 0-7 days on non-accidental, respiratory disease and cardiovascular disease mortalities were 1.05 (95%CI: 1.03-1.07), 1.08 (95%CI: 1.05-1.11) and 1.05 (95%CI: 1.01-1.09) respectively. The effects of heat on YLL for each cause were 23.81 (95%CI: 12.31-35.31), 14.34 (95%CI: 8.98-19.70) and 4.43 (95%CI: 1.64-7.21), respectively. On cold days, 1 ℃ decrease of ambient temperature was correlated with an increase in CRR of 1.06 (95%CI: 1.04-1.08), 1.09 (95%CI:1.06-1.12) and 1.06 (95%CI: 1.02-1.11) from lag 0 to 14 for non-accidental, respiratory disease and cardiovascular disease mortalities, respectively. The estimated YLL were 23.34 (95%CI: 10.04-36.64), 16.39 (95%CI: 10.19-22.59) and 2.61 (95%CI: -0.61-5.82). People aged ≥65 years tend to have higher CRR and YLL than those aged <65 years. On high temperature days, the CRR in women was higher than that in men, while the YLL in women was lower than that in men. On low temperature days, both the CRR and YLL in women were higher than those in men.
Conclusions: Both high and low ambient temperature have adverse health effects. People aged ≥65 years are more sensitive to both high and low ambient temperature. Younger men are more sensitive to high ambient temperature and women and elder men are sensitive to low ambient temperature. It is necessary to take targeted measures to protect the population in Chongqing from the adverse influence of extreme ambient temperature.