The contribution of ship traffic emissions to the air concentrations of secondary inorganic particles (nitrate and sulphate and ammonium) vary between 20-30% in most Western European coastal areas. These results are a first rough estimate from the EMEP Eulerian model and should be validated further. It should also be mentioned that the EMEP Eulerian model generally underestimates the air concentrations of particulate matter although the underestimate is less pronounced for secondary inorganic particles. This means that the results presented here are more uncertain for PM10 than for secondary inorganic aerosols and PM2.5.

URL: http://ec.europa.eu/environment/air/pdf/particulates.pdf