Welding processes consist of joining metals at extremely high temperatures (>4000°C) that generates welding fumes (WF) mainly composed of ultrafine particles (UFP) of metal oxides. Transition metals (Fe, Cu, Cr, Mn …) are known to catalyze the reactive oxygen species (ROS) production. ROS can react quickly with lung fluids and epithelial cells leading to a loss of function. To estimate the potential health effects on exposed workers, analysis may be carried out to characterize the metal content and solubility, and oxidative potential (OP) of WF-UFP. In this work, we determined the influence of several usual storage conditions that could influence the OP and metal bioaccessibility of WF-UFP. The oxidative potential (OPDTT) of WF was evaluated by following the dithiothreitol (DTT) consumption at 412 nm. Our results show that OPDTT of WF-UFP significantly decrease as function of storage duration when they are stored in air/20°C or at -20°C, while there is no significant variations for storage under N2.