Potential adverse health effects of concentrated animal feeding operations (CAFOs), which were also shown in the authors' Lower Saxony Lung Study, are of public concern. The authors aimed to investigate pulmonary health effect of neighboring residents assessed using optimized estimation technique. Annual ammonia emission was measured to assess the emission from CAFO and from surrounding fields. Location of sampling points was optimized using cluster analysis. Individual exposure of 457 nonfarm subjects was interpolated by weighting method. Mean estimated annual ammonia levels varied between 16 and 24 μg/m³. Higher exposed participants were more likely to be sensitized against ubiquitous allergens as compared to lower exposed subjects (adjusted odds ratio [OR] 4.2; 95% confidence interval [CI] 1.2-13.2). In addition, they showed a significantly lower forced expiratory volume in 1 second (FEV₁) (adjusted mean difference in % of predicted -8%; 95% CI -13% to -3%). The authors' previous findings that CAFOs may contribute to burden of respiratory diseases were confirmed by this study.