1. Department of Geography, Geoinformatics and Meteorology, University of Pretoria, Pretoria, South Africa
2. Environment and Health Research Unit, South African Medical Research Council, Pretoria, South Africa
3. Wits Reproductive Health and HIV Institute, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
4. Environment and Health Research Unit, South African Medical Research Council, Johannesburg, South Africa
5. School of Public Health, University of the Witwatersrand, Johannesburg, South Africa
6. Environmental Health Department, Faculty of Health Sciences, University of Johannesburg, Johannesburg, South Africa