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Background The Low Temperature Days (LTD) have attracted far less attention than that of High Temperature Days (HTD), though its impact on mortality is at least comparable. This lower degree of attention may perhaps be due to the fact that its influence on mortality is less pronounced and longer-term, and that there are other concomitant infectious winters factors. In a climate-change scenario, the studies undertaken to date report differing results. The aim of this study was to analyse mortality attributable to both thermal extremes in Spain's 52 provinces across the period 2000–2009, and estimate the related economic cost to show the benefit or “profitability” of implementing prevention plans against LTD. Methods Previous studies enabled us: to obtain the maximum daily temperature above which HTD occurred and the minimum daily temperature below which LTD occurred in the 52 provincial capitals analysed across the same study period; and to calculate the relative and attributable risks (%) associated with daily mortality in each capital. These measures of association were then used to make different calculations to obtain the daily mean mortality attributable to both thermal extremes. To this end, we obtained a summary of the number of degrees whereby the temperature exceeded (excess °C) or fell short (deficit °C) of the threshold temperature for each capital, and calculated the respective number of extreme temperatures days. The economic estimates rated the prevention plans as being 68% effective. Results Over the period considered, the number of HTD (4373) was higher than the number of LTD (3006) for Spain as a whole. Notwithstanding this, in every provincial capital the mean daily mortality attributable to heat was lower (3 deaths/day) than that attributable to cold (3.48 deaths/day). In terms of the economic impact of the activation of prevention plans against LTD, these could be assumed to avoid 2.37 deaths on each LTD, which translated as a saving of €0.29M. Similarly, in the case of heat, 2.04 deaths could be assumed to be avoided each day on which the prevention plan against HTD was activated, amounting to a saving of €0.25M. While the economic cost of cold-related mortality across the ten-year period 2000–2009 was €871.7M, that attributable to heat could be put at €1093.2M. Conclusion The effect of extreme temperatures on daily mortality was similar across the study period for Spain overall. The lower number of days with LTD meant, however, that daily cold-related mortality was higher than daily heat-related mortality, thereby making prevention plans against LTD more “profitable” prevention plans against HTD in terms of avoidable mortality. [ABSTRACT FROM AUTHOR]

A number of studies have shown that there is a time trend towards a reduction in the effects of heat on mortality. In the case of cold, however, there is practically no research of this type and so there is no clearly defined time trend of the impact of cold on mortality. Furthermore, no other specific studies have yet analysed the time trend of the impact of both thermal extremes by age group. We analysed data on daily mortality due to natural causes (ICD-10: A00-R99) in the city of Madrid across the period 2001–2009 and calculated the impact of extreme temperatures on mortality using Poisson regression models for specific age groups. The groups of age selected coinciding with the pre-existing age-groups analyzed in previous papers. For heat waves the groups of age used were: <10 years, 10–17 years, 18–44 years, 45–64 years, 65–74 years and over-75 years. For cold waves the groups of age used were: <1 year; 1–5 years, 6–17 years, 18–44 years, 45–64 years, 65–74 years and over-75 years. <1, 1–17, 18–44, 45–66, 65–74 and over-75 years. We controlled for confounding variables, such as air pollution, noise, influenza, pollen, pressure and relative humidity, trend of the series, as well as seasonalities and autoregressive components of the series. The results of these models were compared to those obtained for the same city during the period 1986–1997 and published in different studies. Our results show a lightly reduction in the effects of heat, especially in the over-45-year age group. In the case of cold, the behaviour pattern was the opposite, with an increase in its effect. Heat adaptation and socio-economic and public-health prevention and action measures may be behind this amelioration in the effects of heat, whereas the absence of such actions in respect of low temperatures may account for the increase in the effects of cold on mortality. From a public health point of view, the implementation of cold wave prevention plans covering all age groups is thus called for. [ABSTRACT FROM AUTHOR]