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A Lagrangian particle-based long-range dispersion model is used to describe the transport of inert chloro-fluorocarbon (CFC) tracer species to Mace Head, a remote location on the Atlantic coast of Ireland, from emission sources in the European continent and from across the ocean in North America. A six-month analysis covering the period January to June 1996 of model and observed trace-gas concentration reveals a high level of model skill with good correlations and no significant bias in our description of long-range transport over the 100-2000 km scale from Europe to Mace Head. Model simulations have also supported previous suggestions that CFCs detected at Mace Head on two occasions during 1994 were of North American origin. A detailed analysis is made of the meteorological processes involved in one of these transatlantic episodes. We estimate that, on average, North American sources may account for only a few per cent of the CFC-11 and other man-made trace gases observed at Mace Head above the northern hemisphere baseline concentrations. During long-range transport events, North American sources may contribute pollutant peaks at Mace Head which are about one order of magnitude smaller in concentration than those from European sources.