Abstracts: ISEE 22nd Annual Conference, Seoul, Korea, 28 August-1 September 2010: Climate Change and Environmental Health
Associations between air temperature and mortality have been consistently observed in studies conducted in Europe and the United States; however, there is still a lack of studies for Asian countries. Our study aimed at investigating the association between daily air temperature and daily cardiovascular as well as respiratory mortality in the urban area of Beijing, China.
Daily death counts for cardiovascular and respiratory diseases for adult residents (≥15 years) and meteorological parameters were obtained from local authorities from January 2003 to August 2005. Confounder-adjusted semiparametric Poisson regression models were used to estimate the effects of 2-day and 15-day temperature averages. Time trend and relative humidity were forced in every model. Exposure-response curves for temperature were estimated using penalized regression splines. Moreover, we analyzed the associations between temperature and mortality for the potentially more susceptible subgroup of elderly people (≥65 years). Effects are presented as relative risk (RR) for mortality per 5°C change in the whole temperature range if the shape of the exposure-response curve was linear, or, if non-linear, for the slopes above a temperature threshold.
We observed J-shaped exposure-response relationships between 2-day average temperature and cardiovascular mortality with a temperature threshold of 23°C. For respiratory mortality, the relationships were considered linear. Overall, a 5°C increase of the 2-day average temperature was associated with a RR of 1.017 (95% confidence-interval [CI]: 1.008–1.027) and 1.143 (95% CI: 1.089–1.199) for cardiovascular and respiratory mortality, respectively. For elderly people, the associations were weaker for respiratory mortality, but stronger for cardiovascular mortality.
Regarding cold effects, a 5°C decrease of the 15-day average temperature was associated with a RR of 1.036 (95% CI: 1.001–1.071) for cardiovascular mortality. Elderly people showed again a similar effect.
Heat as well as cold effects were found for the association of air temperature with cardiovascular and respiratory mortality. Thereby, heat effects were immediate, while with longer time lags cold effects became predominant.