The Atmospheric Infrared Sounder (AIRS) on board NASA's Aqua satellite platform is a hypersectral IR temperature and humidity sounder for numerical weather prediction and climate change studies. We use the rich spectral information available in the AIRS thermal infrared radiances to study the spectral signatures of dust over ocean for four case studies, and to retrieve dust optical depths using a fast two-stream radiative transfer model. Retrieved optical depths for one case, a dust storm spreading over the Eastern Mediterranean in October 2002, are compared with visible imagery and MODIS optical depth retrievals. This work represents a preliminary step to removing the effects of dust on the retrieval of temperature and water vapor from the AIRS measurements.