A screening study was conducted to determine the air quality impacts (annual average ground-level concentrations of SO2 and sulfate) on land due to SOx emissions from ships burning high-sulfur fuel at sea at various distances from the coastline. The CALPUFF dispersion model was used for this screening study. Meteorological inputs were prepared with the CALMET model using the outputs of a prognostic meteorological model, MM5, in combination with surface measurements over water and on land. The meteorology represents the year 2002 because it was the most recent year for which an MM5 simulation covering the contiguous United States was available. CALPUFF tends to overestimate the conversion of SO2 to sulfate in the gas phase and the results presented here are likely to provide conservative estimates of the impacts of emissions from ships at sea on inland air quality (because of the simplified treatment of aqueous-phase chemistry in CALPUFF, this overestimation may not hold for cases where the interactions of the ship plumes with fog dominate sulfate formation).