Various studies have shown that occupational exposures to vapors, gases, dusts, and fumes or their composite measure (VGDF) negatively affect FEV1 and the FEV1/FVC ratio, indicating obstruction of predominantly the large airways (1–3). Recently we have shown that occupational exposure to pesticides is associated with substantial losses of large airway function in the general population (3). The negative effects of occupational exposures on the level of lung function were generally more pronounced in ever- than in never-smokers, suggesting that cigarette smoke–induced damage increases the susceptibility of the airways to other exposures (3). In addition to interest in large airways obstruction, there is considerable renewed interest in obstruction of the small airways, since small airways obstruction is one of the three main phenotypes of chronic obstructive pulmonary disease (COPD) (4, 5).