Field study on atmospheric emissions and profiles of heavy metal-containing nanoparticles from multiple full scale industrial sources in China

Abstract

Inhalation of exogenous heavy metal-containing nanoparticles (HM-containing NPs) poses considerable health risks, yet their source-specific industrial emissions remain poorly characterized. This study employed an automated isokinetic sampling system to collect particulate matter (PM), and used single particle inductively coupled plasma time-of-flight mass spectrometry (SP-ICP-TOF-MS) to quantify ten HM-containing NPs in the collected samples from 132 full-scale industrial plants across 13 sectors in China. Sn, Mn, Zn, and Cu exhibited particularly high particle number concentrations (PNCs), with hazardous waste incinerators (HWIs) and electric arc furnaces (EAFs) identified as dominant emission sources. Notably, HWIs emitted Sn-containing NPs at a peak PNC of 8.8 × 10¹¹ particles per g. Across the representative industrial sectors in China, Mn-, Sn-, and Zn-containing NPs were the most abundantly emitted, with estimated annual releases of 1.6 × 10²³, 4.6 × 10²², and 2.0 × 10²² particles, respectively. Coal-fired power plants and cement kilns co-processing solid waste also contributed significantly. Exposure assessment—based on a steady-state atmospheric model and standard U.S. EPA inhalation and dermal exposure equations—revealed that, in highly impacted provinces, adults face cumulative exposure to HM-containing NPs up to 10⁵ particles per kg body weight per day, while children's exposure levels are more than double. These findings provide the first large-scale quantification of HM-containing NP emissions across multiple industries, offering critical data for exposure assessment and risk management. The results highlight HWIs and EAFs as key sectors for prioritized emission control, particularly to reduce exposure risks associated with high-emission HM-containing NPs such as Sn, Mn, Zn, and Cu in densely populated industrial regions.