Air pollution epidemiologic studies in South Africa--need for freshening up

The results of epidemiologic studies obtained in developed countries cannot be extrapolated with complete confidence to developing countries. The objectives of this review were to examine the evidence from local studies for associations between air pollution and adverse health along with a critical review for methodologic limitations. The literature search strategy and selection criteria involved a MEDLINE search up to June 2005. Of 267 journal articles found, 14 focused on air pollution epidemiology (excluding active smoking and internal dose as a proxy for health outcomes). Two studies were also located by word of mouth or through the references from the selected studies. The local studies provide some evidence of an association with a range of serious and common health problems. No study established an exposure-response curve for the criteria pollutants carbon monoxide, sulfur dioxide, nitrogen oxides, lead, and ozone. Therefore, using the results of such studies in risk-assessment is impossible. The studies were fraught with systematic and random errors, which limit their validity and precision. We recommend conducting a quantitative intervention study with an analytical study design in all major cities in the countries where residents are still using dirty fuels for cooking, lighting, and space heating. Future studies must involve national and international multidisciplinary stakeholders and must be planned well in advance.