The cellular oxidative stress by the exposure of diesel exhaust particles (DEPs) was investigated by using a time of flight secondary ion mass spectrometry (TOF-SIMS) and a real time reverse transcription polymerase chain reaction (RT-PCR) and a scanning transmission electron microscope (STEM). The DEP surfaces which had different properties were prepared for examining the oxidative stress by a gas chromatography mass spectrometry (GC-MS). We characterized the compositions in the different DEP surfaces and measured the gene expression of heme oxygenase-1 (HO-1) which were induced for preventing the cellular oxidative stress. From these results, it was clear that the DEP compositions (Fe, etc.) correlated closely with the cellular oxidative stress. From the results of a STEM analysis, we found out that the DEP were taken up in the cell and that some mitochondria in close association to the DEP showed damaged morphology. Moreover, the iron oxide nanoparticles of several nanometer were aggregated in the DEP. We therefore concluded that there was the interaction between the cellular functions and the particle properties. (c) 2008 Elsevier B.V. All rights reserved.