During the summer months, Nova Scotia is downwind of many of the large industrial areas of the eastern United States and central Canada. The studies described here were carried out in the summers of 1983 and 1984 in Antigonish, a small rural town in northeastern Nova Scotia with no local sources. Twenty-four hour samples were collected on Teflon filters using a dichotomous sampler, and were analyzed for sulphate, nitrate and chloride by ion chromatography and for strong acid using Gran titrations. Sulphate episodes (up to 27 μg m-3) were frequent. They usually occurred in warm, hazy weather and were often accompanied by strong acid (up to 9 μg m-3 as H2SO4).