Epidemiological studies consistently link ambient concentrations of particulate matter (PM) to negative health impacts, including asthma, heart attacks, hospital admissions, and premature mortality. The authors model ambient PM concentrations from ocean going ships using two geospatial emissions inventories and two global aerosol models. The authors estimate global and regional mortalities by applying ambient PM increases due to ships to cardiopulmonary and lung cancer concentration risk functions and population models.