Background: The Vaal Triangle is an area generally associated with a number of harmful determinants of health since it houses diverse industrial processes and industrial development in South Africa, hence being categorised as an outdoor air pollution priority area in 2006. Method: A cross-sectional inter-comparative study to the 1990 Vaal Triangle Air Pollution and Health Study (VAPS) was conducted in 2010. The main objectives of this study were to measure the prevalence of upper and lower respiratory illnesses of 10-year-old children in 2010 and compare those findings to the 1990 study, and lastly to identify risk and protective factors for respiratory illnesses in 1990 and in 2010. In addition, the association between exposure factors (risk and protective factors) that are sources of indoor air pollution and factors related to diet and household living conditions and their associations with upper and lower respiratory health illnesses in 1990 and 2010 was determined. Results and Discussion: The prevalence of the respiratory health outcomes in the 1990 study and 2010 study cannot be compared directly since a 1-year prevalence was determined in 1990 and a 6-month prevalence in 2010. Throughout the dissertation this should be kept in mind. The change in prevalence of a respiratory health outcome observed in 1990 and in 2010 is just an indication of the possible change. The 1990 1-year prevalence and the 2-week 2010 prevalence of asthma were the same in the two study populations (i.e. 12%). The 6-month prevalence of sinusitis, bronchitis and pneumonia in 2010 was lower when compared to the yearly prevalence of these illnesses in the 1990 study. On completion of the multivariate analyses, in 1990 study, the use of a gas heater acted as a risk factor for pneumonia (a lower respiratory illness), with a odds ratio of 3.67 (1.15-11.71) and a p-value of 0.03, whilst environmental tobacco smoke within the household was protective of hay fever and sinusitis (upper respiratory illnesses). In the 2010 study, the consumption of chicken and/or fish and fruit at least three times a week was protective of bronchitis (with odds ratios of 0.23 and 0.26 respectively). Conclusion and Recommendations: It is not certain whether the change in the respiratory health status of 10-year-olds living in the Vaal Triangle is real as the prevalence of health outcomes in the two studies cannot be compared directly to one another due to the differences in prevalence time periods in the two studies. Nevertheless, a statistically significant change was observed in the prevalence of sinusitis, earache, bronchitis, and pneumonia between the two study populations. It is imperative to have a study protocol; this ensures all levels of measure are consistent in both studies and leads to a dataset of high quality. There is also a need for more analytical epidemiological studies (i.e. cohort, time-series, case-crossover and panel studies) to be done in South Africa, addressing indoor and outdoor air pollution and respiratory health. / Dissertation (MSc)--University of Pretoria, 2013. / gm2014 / School of Health Systems and Public Health (SHSPH) / unrestricted