M Negev1, R S Kovats2. 1. School of Public Health, University of Haifa, 199 Aba Khoushy Ave., Mount Carmel 3498838, Israel. Electronic address: maya.negev@gmail.com. 2. Department of Social and Environmental Health Research, London School of Hygiene and Tropical Medicine, 15-17 Tavistock Place, London WC1H 9SH, UK.