Emissions and Exposure: Case Studies and Strategies for Safe Handling of Nanocellulose

Inhalation exposure, particularly in occupational settings, is widely recognized as a high-risk scenario for nanomaterials. This chapter focuses on airborne emissions and inhalation exposure associated with nanocellulose materials (NCMs), including cellulose nanofibrils (CNFs; also called cellulose nanofibers) and cellulose nanocrystals (CNCs). Existing literature on NCM emissions and exposure is briefly reviewed, followed by the presentation of case studies conducted under the NEDO projects, primarily targeting CNFs. These case studies include workplace measurements performed at CNF dry powder production and composite manufacturing sites, as well as simulated tests involving dry powder handling, droplet release from aqueous suspensions, and grinding or abrasion of CNF-containing composites. The findings indicate that dry NCM powders present the highest potential for airborne release and inhalation exposure, whereas aqueous suspensions are less prone to aerosolization and typically result in exposure to dried, aggregated particles. During grinding or abrasion of CNF-containing composites, most airborne particles consisted of resin fragments or resin–CNF mixtures, with CNFs remaining largely embedded and minimal direct exposure to isolated fibers. Based on these findings, key processes requiring attention, recommended countermeasures and management strategies, and practical measurement methods for emissions and exposure are summarized.