Observations of O3, CO, and aerosols taken in the vicinity of Halifax, Nova Scotia, during the summers of 1992 and 1993 indicate long-range transport of O3 that was photochemically generated within urban areas of North America. We identify eastward moving cyclonic systems as the main synoptic-scale transport mechanism into this region with the consequence that transport events are highly episodic. The potential for further well-defined long-range transport was found to be slight as a result of subsequent mixing by these cyclonic systems. The ozone flux associated with these cyclones into the lowest 1.5 km of this region is estimated to be on the order of 1 Gmol per 24-hour cyclonic event. We conclude that the circulation patterns associated with these fronts are a major pathway for the export of pollutants from North America. ¿ American Geophysical Union 1996