Nanoparticles from paper mills: A seasonal, numerical and morphological analysis

The purpose of this article is to evaluate the potential risk of exposure to nanoparticles of workers in paper mills. In the final stage of the paper production, the very large sheets are wound onto large reels, where these are processed depending on their ultimate use. Paper is smoothed and compacted by passing through metal rollers. During these mechanical treatments nanometric ultrafine particles are generated. In particular, the nanoparticle presence, size and morphology were investigated and differences between particles produced either in summer or winter seasons were explored. To this aim Atomic Force Microscopy (AFM) and Dynamic Light Scattering (DLS) were employed to analyze nano powders filtered in environments of different paper mills to determine structural morphology and sizes. Large breathable particles, with size in the range from 4. μm to 250. nm have been sampled to evaluate the mean level of exposure. By comparing nanoparticles collected from paper mills in summer and in winter we revealed that the number of nanoparticles collected in winter is strictly related to heat generated by the heating system.