The magnitude and variation of SO 2 and smoke concentrations in rural areas of East Hampshire and West Sussex were examined in relation to the import of emissions from adjacent and distant sources. Distinct topographic patterns in the ground level concentrations were found to constitute an important characteristic of pollution dispersal in the study area. In the case of SO 2, evidence from a rural network of monitoring sites and from an experiment in which vertical gradients of pollution were measured on a pylon tower revealed that the predominant pattern is one in which amounts are greater at elevated sites than at sites in valleys and embayments. The opposite pattern was found also to be important in summer months. Smoke concentrations are frequently higher on low-lying areas. The meteorological conditions conducive to the generation of the main topographic patterns are elucidated, together with the dispersal mechanisms involved.