Characterization of Occupational Exposures to Engineered Nanoparticles During the Finishing Process of a Hardwood Floor Manufacturing Plant.

Engineered nanomaterials (ENMs) have an enormous economic impact. In the surface coating industry, titanium dioxide (TiO2) and silicon dioxide (SiO2) nanoparticles are commonly incorporated into varnishes, paints, and finishing products. These ENMs are used for UV-active properties and self-cleaning activities, as well as for the durability and resistance they provide. However, several health concerns are associated with the inhalation of some ENMs. In this case study, occupational exposures to engineered nanoparticles were investigated in an industrial hardwood floor manufacturing plant during the finishing task of an automated spraying equipment. A combination of air and surface sampling was carried out during two workdays. Airborne and deposited particles were measured using a combination of real-time and filter-based sampling methods and analyzed by microscopy and spectrometry. Results indicate that the wood floor coating process generates airborne TiO2 and SiO2 nanoparticles which include individual particles in the nanoscale range (lower than 100 nm) and agglomerated particles of several hundred nanometers containing individual nanoparticles. Finishing activities significantly increased total particle number concentrations (45 620 and 117 880 particles cm-3) and surface-specific mass concentrations (154 µm2 cm-3). Concentrations of TiO2 ranged from 13 to 97 µg m-3 for personal measurements and from 36 to 55 µg m-3 for ambient measurements in the finishing location. Characterization of the deposited particles indicated the dispersion of the engineered airborne nanoparticles from the finishing location to the packaging area. Using a multimetric approach, this study shows high evidence that the worker was exposed to engineered TiO2 and SiO2 nanoparticles during the finishing process of the wood floor production facility. In addition, this study indicates that workers outside the finish spray area could be exposed to airborne engineered TiO2 and SiO2 nanoparticles coming from the finishing process.