The National Institute for Occupational Safety and Health (NIOSH) posted a blog item on August 1, 2024, entitled “When Nanoparticles Blow Up — Explosion Hazards of Nanoparticles.” According to the blog item, little is known about the potential explosivity of any material when subdivided down to the nanoscale, prompting the NIOSH Nanotechnology Research Center (NTRC) to study the explosivity of several classes of nanoparticles:

• Nanocarbons: NIOSH screened single-walled carbon nanotubes, multi-walled carbon nanotubes, carbon nanofibers, graphene, diamond, and fullerene for potential explosion hazard. The blog item states that these nanomaterials “are ‘weakly explosive’ (European Dust Explosion Class St-1), similar to cotton and wood dust. The explosion severity did not depend on primary particle size.”
• Nanocellulose: According to the blog item, nanocellulose (both nanocrystalline and nanofibrillated) “is ‘strongly explosive’ (European Dust Explosion Class St-2), similar to wood flour. The smaller particle size appears not to alter either the combustion mechanism or the explosion parameters.”
• Nanometals: NIOSH screened several nanometals, finding that “aluminum and titanium are ‘very strongly explosive’ (European Dust Explosion Class St-3).” The item states that “[f]urther study is needed on the explosion characteristics of these industrially important but potentially dangerous nanometals, especially systematically quantifying the passivating role of surface oxides.”

The blog item states that “[c]ombustibility should continue to be studied as new and more advanced materials are developed and used in commerce. Manufacturers, suppliers, and end-users should consider these combustibility characteristics when working with nanomaterials to prevent explosions and keep workers safe.”