Quantification and characterization of manufactured nanomaterials shed from face masks

Face masks are an important public health measure whose use became wide-spread during the pandemic. Manufactured nanomaterials (MNMs) have been incorporated into face masks to enhance their anti-microbial and self-cleaning properties. However, the potential toxicity of certain MNMs raises concerns regarding their use in facemasks. Limited research has addressed the airborne shedding potential of MNMs as it relates to inhalation uptake. This work aimed to address this gap by investigating the potential airborne release of TiO2 from the outer surface of three general purpose face masks, under two sets of conditions: physically stable and physically agitated. The surface of the face masks was analyzed to determine the mass fraction of TiO2 and the composition of the particles detected. Particle shedding was quantified via particle counters, particle sizers, electron microscopy, and inductively-coupled-plasma mass spectrometry (ICP-MS). Compositional analysis showed that all tested masks contained different levels of Ti ranging from 80 to 4870 µg/g of mask, with TiO2 particles detected on the surface of the fibers. Particle shedding was observed only for two of the masks under agitation with low average concentrations of 130 and 520 #/cm3. Further analysis of the shed particles did not indicate the presence of TiO2 nanoparticles. Overall, these findings suggest that while TiO2 was present in the face masks, its airborne release under typical conditions may be unlikely. Although additional efforts are needed to characterize a wider range of facemasks and expand on these data, this study contributes to the understanding of inhalation uptake from MNMs shedding to inform future risk assessments.