Environmental exposure to tobacco smoke and contaminants from unvented cooking stoves has been linked to impaired pulmonary function and respiratory diseases. These risk factors exist to a greater extent in developing countries and, in the case of exposure to tobacco smoke, they are reported to be increasing. In this study, pulmonary function studies were performed on 1905 children in Jordan. The effect of exposure to these environmental factors on respiratory function was analyzed. A significant negative impact was found with regard to environmental exposure to both passive smoking and wood and kerosene unvented cooking stoves. The mean values of lung function in children exposed and not exposed to passive smoking were, respectively, FVC (L): 1.29-1.49; FEV1 (L): 1.2-1.4; FEF25-75 (L/S): 1.84-2.24; PEFR (L/S): 2.6-3.21, and to wood and kerosene were FVC (L): 1.02-1.32; FEV1 (L): 0.91-1.25; FEF25-75 (L/S): 1.24-1.86; PEFR (L/S): 1.67-2.64. This is a major problem in developing countries because of the increasing incidence of smoking and the high exposure to pollution risk factors.