“…A low prevalence of asthma and atopy has been shown in farmers and agricultural workers, but a high prevalence of respiratory symptoms related to chronic bronchitis and COPD has been established [5,6]. Although farmers tend to smoke less often than the general population [7,8], a higher prevalence of COPD has been suggested in subjects exposed to farm animals, especially swine, poultry and cattle [5,[9][10][11]. However, a cross-sectional study of the risk of COPD in farmers using nonfarming working subjects as controls is still lacking, and there are conflicting data regarding the magnitude and determinants of COPD risk in farmers [5,9,10].…”