Towards a surface metric to measure the dustiness of nanomaterial powders

Relevancy of dustiness methods are increasingly recognized in a preliminary exposure evaluation of workers handling nanomaterials in powder form. Until now, the methods recommended in the current European standards mainly indicate to determine a mass-based dustiness index [mg/kg], while the surface area is regularly highlighted as a more appropriate determinant for assessing the pulmonary toxicity of nanoparticles.<br/>
In this study, we describe an operational methodology leading us to suggest propose a surface metric to determine the dustiness index [m /kg] of nanoparticulate matter. To this end, we assume demonstrate the equivalence between the external specific surface area of a nanopowder and the one of its aerosol. This assumption was demonstrated with five nanomaterials produced and used at the industrial scale, and covering a range of external specific surface areas from 35 to 228 m /g. Compared to the conventional mass-based dustiness index, the surface-based dustiness index is 1) more discriminant, allowing one extra order of magnitude to be covered, and 2) has an impacts on the powder ranking with potential consequences on the preventative measures to implement. Finally, our proposal has the potential to be included in the future European standards revisions related to workplace exposure and dustiness measurement, provided that more additional experimental results on surface-based dustiness indices comfort these preliminary data.