Data for: Vehicle Emission Standard Upgrades Cut Nitro-PAH Mass but Increase Toxicity-Weighted Burden: Evidence from Paired Tunnel Campaigns

Vehicular emissions are a major urban source of nitrated polycyclic aromatic hydrocarbons (NPAHs), yet the health implications of recent emission standard upgrades remain unclear. We conducted two comprehensive tunnel campaigns in Guangzhou (2014 vs 2019) to quantify changes in PM2.5-bound NPAHs using GC-NCI-MS speciation of 20 congeners, regression-based separation of diesel and gasoline contributions, and toxicity weighting via benzo[a]pyrene toxic equivalents (TEQBaP). Fleet-average mass-based NPAH emission factors declined by 57.8% from 7.06 to 2.98 μg veh-1 km-1, yet TEQBaP increased by 28.3% from 2.69 to 3.45 μg veh-1 km-1, revealing a decoupling of mass from carcinogenic potency. In 2019, diesel vehicles comprised 3.3% of the fleet but produced 91.0% of NPAH emissions, and a compositional shift toward higher-potency congeners (e.g., 6-nitrochrysene and dinitropyrenes) offset the apparent health gains from mass reduction. Diurnal variability in emission factors tracked the diesel fraction, highlighting the outsized influence of diesel activity on real‑world toxicity. Collectively, these results provide field evidence that mass-only metrics can underestimate risk following technology and regulatory changes, and they motivate toxicity-weighted indicators and diesel-targeted control strategies for managing NPAH hazards in modern fleets. This dataset contains the raw data used for the analyses in the manuscript titled "Vehicle Emission Standard Upgrades Cut Nitro-PAH Mass but Increase Toxicity-Weighted Burden: Evidence from Paired Tunnel Campaigns"