NaH can ignite spontaneously in air. It also reacts vigorously with water or humid air to release hydrogen, which is very flammable, and sodium hydroxide (NaOH), a quite corrosive base. In practice, most sodium hydride is sold as a dispersion in mineral oil, which can be safely handled in air. Although sodium hydride is widely used in DMSO, DMF or DMAc for SN2 type reactions there have been many cases of fires and/or explosions from such mixtures.