1 Global Change and Sustainability Research Institute, University of the Witwatersrand, Braamfontein, Johannesburg, South Africa.
2 Department of Public Health, Environmental and Social Determinants of Health, WHO, Geneva, Switzerland.
3 Department of Social and Environmental Health Research, London School of Hygiene & Tropical Medicine, London WC1H 9SH, UK. Electronic address: andy.haines@lshtm.ac.uk.
4 Nicholas School of the Environment, Duke University, Durham, NC, USA.