High levels of endotoxin are found inside and near to animal houses. However,there is a lack of data on environmental endotoxin in areas with intensive animal production facilities.We conducted a cross-sectional study of respiratory health in two villages of Lower Saxony with intensivelivestock production. We assessed the level of endotoxin exposure in the backyards of 32 participantswith two 24-hours measurements of inhalable fraction (one in winter and one in summer). The geometricmean (geometric standard deviation) of the levels of endotoxin varied between 2.0 (2.9) EU/m3 in winterand 2.9 (2.4) EU/m3 in summer. Potential predictors--season, sampling sites, and weather conditions--explained24% of the variability in ambient endotoxin concentration in the study area. The results indicate that,compared with urban residents, exposure to endotoxin is greater among people living in rural areas withintensive animal production. This might affect their respiratory health. However, these exposures arecharacterized by a large spatial variability.