Hindawi Publishing Corporation he Scientiic World Journal Volume 2013, Article ID 961750, 15 pages http://dx.doi.org/10.1155/2013/961750 Research Article Environmental Temperature and Thermal Indices: What is the Most Effective Predictor of Heat-Related Mortality in Different Geographical Contexts? Marco Morabito, 1,2,3 Alfonso Crisci, 4 Alessandro Messeri, 2 Valerio Capecchi, 4 Pietro Amedeo Modesti, 2,5 Gian Franco Gensini, 2,5 and Simone Orlandini 1,2,3 1 Department of Agrifood Production and Environmental Sciences, University of Florence, Piazzale delle Cascine 18, 50144 Florence, Italy 2 Interdepartmental Centre of Bioclimatology, University of Florence, Piazzale delle Cascine 18, 50144 Florence, Italy 3 Center for Civil Protection and Risk Studies, University of Florence (CESPRO), Viale Morgagni 48, 50134 Florence, Italy 4 Institute of Biometeorology, National Research Council, Via Giovanni Caproni 8, 50145 Florence, Italy 5 Clinica M´ edica e Cardiologia, University of Florence, Viale Morgagni 85, 50134 Florence, Italy Correspondence should be addressed to Marco Morabito; marco.morabito@unii.it Received 13 August 2013; Accepted 18 October 2013 Academic Editors: J. Pinto and M. Saez Copyright © 2013 Marco Morabito et al. his is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. he aim of this study is to identify the most efective thermal predictor of heat-related very-elderly mortality in two cities located in diferent geographical contexts of central Italy. We tested the hypothesis that use of the state-of-the-art rational thermal indices, the Universal hermal Climate Index (UTCI), might provide an improvement in predicting heat-related mortality with respect to other predictors. Data regarding very elderly people (≥75 years) who died in inland and coastal cities from 2006 to 2008 (May– October) and meteorological and air pollution were obtained from the regional mortality and environmental archives. Rational (UTCI) and direct thermal indices represented by a set of bivariate/multivariate apparent temperature indices were assessed. Correlation analyses and generalized additive models were applied. he Akaike weights were used for the best model selection. Direct multivariate indices showed the highest correlations with UTCI and were also selected as the best thermal predictors of heat-related mortality for both inland and coastal cities. Conversely, the UTCI was never identiied as the best thermal predictor. he use of direct multivariate indices, which also account for the extra efect of wind speed and/or solar radiation, revealed the best itting with all-cause, very-elderly mortality attributable to heat stress. 1. Introduction he relationship between high environmental temperature and human mortality has been widely investigated and at the present time a large amount of scientiic studies and 1 detailed reviews are available for people living in diferent geographical areas [1–5]. However, the correct interpretation and comparison of results from environmental epidemio- logical studies are not immediate because diferent ther- mal/temperature based health-impact indicators have been adopted. For example, several authors used air temperature variables (such as daily average, maximum, and minimum air temperature) as environmental predictors of human mortal- ity [3, 6, 7], while others used alternative temperature metrics which condense all the extra meteorological efects (i.e., air humidity, wind speed, and solar radiation) into a single num- ber derived by means of more or less complex thermal indices [8–11]. hermal indices are useful tools for summarizing the interaction of thermal environmental stressors on humans. hermal indices can be categorized by direct (based on direct measurements of environmental variables), empirical (based on objective and subjective stress), or rational (based on calculations involving the human heat balance) indices [12]. Most studies examined to evaluate the impact of heat stress on mortality mainly used direct indices, especially because they