Excessive air pollution by industries in the Sasolburg area is suspected of affecting the residents' health in general and the respiratory system in particular. In the present investigation children from primary schools at Sasolburg were compared with those from the neighbouring rural towns of Parys, Heilbron and Frankfort, all with negligible air pollution levels. Although no important differences in the incidence of respiratory illness were evident from the questionnaire administered, there was a significant difference in the forced expiratory volume in 1 second (FEV1) of boys in the two groups. In addition there was an observed trend for all lung functions to be slightly worse in the study area. This trend seemed to be unaffected by the smoking habits of families but the social class from which the children originated might have been a contributory factor.