Work

Emission standard upgrades decouple nitro-PAH mass from toxicity in real-world fleets

Year: 2025

Type: article

Abstract: : Vehicular emissions are a major urban source of nitrated polycyclic aromatic hydrocarbons (NPAHs), yet the impact of recent emission standard upgrades on NPAH mass and toxicity remains unclear. We conducted two comprehensive tunnel campaigns in Guangzhou (2014 and 2019) to quantify changes in PM 2.5 -bound parent PAHs and NPAHs from real-world vehicle fleets. Fleet-average mass-based emission factors (EFs) for total PAHs and total NPAHs decreased by 74.8% (45.22 to 11.39 μg km -1 veh -1 ) and 57.8% (7.06 to 2.98 μg km -1 veh -1 ), respectively. In contrast, the total carcinogenic potency of the NPAH mixture, expressed as benzo[a]pyrene toxic equivalents (TEQ BaP ), increased by 28.3% (2.69 to 3.45 μg km -1 veh -1 ). This divergence reflects a compositional shift in the traffic fleet: in 2019 diesel vehicles constituted only 3.3% of traffic but accounted for 91.0% of NPAH emissions with enrichment in high-potency congeners such as dinitropyrenes. These real-world measurements demonstrate that mass-only metrics for regulated (PAHs) and unregulated (NPAHs) emissions can be misleading, and highlight the need for toxicity-weighted indicators and diesel-targeted control strategies to manage NPAH hazards in modern fleets.

Source: Environmental Pollution

DOI: 10.1016/j.envpol.2025.127482

Authors: Shaoxuan Xiao, Runqi Zhang, Wei Song, Yanli Zhang, Xinming Wang

Institutions: Chinese Academy of Sciences, Guangzhou Institute of Geochemistry, University of Chinese Academy of Sciences, Shanxi Polytechnic College, Taiyuan University of Science and Technology

Language: English

Topic: Toxic Organic Pollutants Impact

Subfield: Health, Toxicology and Mutagenesis

Field: Environmental Science

Domain: Physical Sciences

SDGs: Good health and well-being, Sustainable cities and communities, Climate action

Open Access status: hybrid

Estimated APC paid: $4,090