Electroplating architecture as an organizer of airborne exposure and inhalation risk in Ni/Cr ABS microenvironments

By jointly resolving microporous nickel (MPN) operations and chromium speciation within a full-scale system, this study clarifies how multilayer Ni/Cr architecture reorganizes airborne exposure and inhalation risk at the unit level. In an acrylonitrile butadiene styrene (ABS) electroplating line comprising sixteen hoist units, aerosols were comprehensively characterized for particle metrics, organic contaminants, and inorganic constituents. Volatile organics exhibited pronounced unit-specific variability, with isopropanol reaching 18,937.41 ± 4392.88 µg m⁻³ during degreasing (DG) and methylene chloride peaking at 25,884.34 ± 6218.77 µg m⁻³ during lacquer stripping (LS), while persistent organics showed µg m⁻³ -level phthalates and sub-µg m⁻³ per- and polyfluoroalkyl substances (PFAS). Inorganic aerosols were sharply segregated by unit function: airborne Ni peaked during electroless nickel (EN) (6673.42 ± 1489.64 µg m⁻³) and declined across subsequent multilayer bright nickel (MBN) steps, whereas Cr(VI) reached 418.74 ± 92.52 µg m⁻³ exclusively in Hexavalent chromium (HCP) units. Particle size distributions (PSD) were highest during HCP (2.37 × 10⁷), whereas nanoparticle fractions peaked during degreasing (DG) and product drying (PDry). Screening-level risk metrics followed the same architectural pattern, with summed hazard quotient (ΣHQ) dominated by particle-associated metals (58.90-1908.47) and summed excess lifetime cancer risk (ΣELCR) (×10⁻⁶) governed by Cr(VI) and Ni, forming distinct hotspots at HCP (5.03) and EN (1.75). These results demonstrate strong unit-level segregation of airborne exposure and inhalation risk in the investigated ABS electroplating line, consistent with electrochemical architecture under a shared facility ventilation configuration rather than simple linear unit order.