Trend and health risk of carcinogenic particulate nitrosamines in the atmosphere in Seoul, South Korea

This study investigates the trend and health risk associated with carcinogenic particulate nitrosamines in the atmosphere of Seoul, South Korea from 2013 to 2019. The average concentration of five particulate nitrosamines (NDEA, NDBA, NPIP, NPYR, and NMEA) during this period was 3.94 ± 8.38 ng/m³, while seven particulate nitrosamines (including NDMA and NMOR) averaged 8.96 ± 16.94 ng/m³. Mann-Kendall analysis revealed that while overall nitrosamine levels showed no notable trend, decreasing trends were observed for NDMA (τ = −0.12, p < 0.05) and NDEA (τ = −0.45, p < 0.001), while NDBA showed an increasing trend (τ = 0.20, p < 0.001). Analysis of correlations of the observed nitrosamines with primary emission indicators (PAHs and CO) and atmospheric reactants (NO, NO₂, and O₃) suggests contributions from both primary emissions and secondary formation processes. Nitrosation appears to be the major reaction pathway, particularly in cold seasons, as evidenced by strong correlations with NO₂ and liquid water content, while ozonation could affect the particulate nitrosamines formation in warm season. A health risk assessment was conducted using Monte Carlo simulations based on the Korean exposure factors database. The median cumulative lifetime cancer risk from particulate nitrosamines in Seoul was estimated at 10⁻⁷ to 10⁻⁵, which falls within the generally acceptable risk range (10⁻⁶ to 10⁻⁴). The highest risks were observed in winter 2018 (ranging from 7.16·10⁻⁷ to 6.10·10⁻⁶), with the age group 3–19 showing the highest risk levels. The risk levels in Seoul were comparable to those observed in other urban areas such as Chuncheon, Korea and North Kensington, UK (∼10⁻⁶). The increasing trend in nitrosamine concentrations, despite being within acceptable risk ranges, highlights the need for continued monitoring and potential mitigation strategies, particularly during winter months when risk levels are elevated.