Objective: To explore the relationship between temperature and non-accidental mortality in Guangzhou, Changsha and Kunming;to evaluate the temperature-related risk of mortality; and thereby to provide scientific evidence for enacting the policy to tackle climate changes.
Method: Daily meteorology data and mortality data were collected in 2006-2009 in Guangzhou, Changsha and Kunming. Distributed lag non-linear model (DLNM) was established and applied in a case-crossover design, which controlled the secular trend of time, to estimate the specified effects of temperature on non-accidental mortality at conditions of lag 0-2, lag 0-18 and lag 0-27 days, respectively.
Result: An obvious seasonal periodicity was found in non-accidental mortality in Guangzhou, Changsha and Kunming during 2006-2009. The mortality number was comparatively high in the winters, and some high temperature days in summer; but was comparatively low in springs and autumn. An L-shaped relationship was found between temperature and mortality in Guangzhou and Kunming and a U-shaped relationship was found in Changsha. When daily mean temperature exceeded 28.2 °C, 24.5°C and 23.2°C, as average temperature increase 1°C, non-accidental mortality increased 4.56% (95%CI:2.74%-6.63%), 5.66% (95%CI:0.22%-12.65%) , -3.94% (95%CI:-32.77%-39.01%) , respectively; when daily mean temperature below 24.8°C, 20.0°C and 17.3°C, as average temperature decrease 1°C, the corresponding increase in non-accidental mortality were 3.28% (95%CI:2.41%-4.10%) (lag 0-18 days), 1.35% (95%CI:0.31%-1.77%) (lag 0-2 days) and 2.42% (95%CI:1.08%-3.27%) (lag 0-27 days) , respectively. The effects of hot weather were acute and short term; while the effects of cold weather had a several days delay, but a longer persistence.
Conclusions: Extreme cold and hot temperature could increase the risk of non-accidental mortality in Guangzhou, Changsha and Kunming. The effects of cold weather had a several days delay, but a longer persistence.