This study evaluates respiratory symptoms, lung function, and exposure to airborne particles among waste-picking children. We enrolled 103 waste-picking children at a dump in Managua, Nicaragua and 103 children who do not pick waste. Exposure to airborne particles was assessed by area sampling. Health data were obtained from a questionnaire, clinical examination, and spirometry. Exposure effects were evaluated with multivariate regression analysis. Exposure to particles exceeded national and international standards. Wheezing among children was related to exposure status, with waste-picking children who are both "never highly exposed" and "ever highly exposed" having greater prevalence of wheezing compared to the children who do not pick waste. FEV1 among "ever highly exposed" waste-picking children with wheeze was 13% lower than non-waste-picking children with wheeze. Exposure to small particles was unacceptably high and associated with wheeze and decreased lung function.