Results of the epidemiological study of relationships between air temperature and daily mortality in Chisinau (Moldova) are presented. The research’s main task included description of mortality dependence on different temperature variables and identification of thermal optimum (minimal mortality temperature, MMT). Total daily deaths were used to characterize the mortality of urban and rural populations in April–September of 2000–2008, excluding the extremely warm season of 2007. The simple moving average procedure and 2nd-order polynomials were used for daily mean ( ), maximum ( ), and minimum ( ) temperatures and mortality approximation. Thermal optimum for mortality in Chisinau (15.2 deaths) was observed at , , and about 22°C, 27-28°C, and 17-18°C, respectively. Considering these values as certain cut-points, the correlations between temperature and mortality were estimated below and above MMTs. With air temperatures below its optimal value, each additional 1°C increase of ( , ) was accompanied by 1.40% (1.35%, 1.52%) decrease in daily mortality. The increase of and above optimal values was associated with ~2.8% and 3.5% increase of mortality; results for were not statistically significant. The dependency of mortality on apparent temperature was somewhat weaker below MMT; a significant relationship above MMT was not identified. 1. Introduction Mortality rates are ambient temperature dependent and have long been associated with the effects of both heat and cold. Research by epidemiologists and climatologists has grown rapidly following the European heat waves in 2003 [1–11]. That summer many western European countries experienced dramatic death tolls, and temperatures were considered as “a shape of things to come” [12]. However, while an analysis of isolated heat waves provides a useful insight into the short-term response of populations to these events, the time-series epidemiological analysis of temperature-mortality association over a long time period enables the investigation and quantification of not only general temperature-related mortality dependencies, but also additional meteorological, environmental and social confounding risk factors (e.g., [1, 13–16]). In such studies, a J- or U-shaped relationship between temperature and mortality is often identified [4, 6]. Air temperature is usually expressed in terms of its mean ( ), maximum ( ), or minimum ( ) values as well as the composite indices such as apparent temperature (AT) that takes into account humidity; in particular, it was shown that heat-related mortality is generally better identified
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