Real-World Particle Emissions from a Modern Heavy-Duty Diesel Vehicle during Normal Operation and DPF Regeneration Events: Impacts on Disadvantaged Communities.

We assessed the real-world particulate emissions of a goods movement diesel vehicle, with an emphasis on total particle number and solid particle number emissions at different cutoff sizes. The vehicle was tested on routes in the South Coast Air Basin (SCAB) of California, representative of typical goods movement operation between the ports to warehouses and logistic centers with a mixture of urban and highway driving, as well as elevation change. We evaluated emissions during normal vehicle operation and diesel particulate filter (DPF) active regeneration events. Results revealed small variations in particle emissions between the routes, with particles below 23 nm and even 10 nm being abundant in the exhaust. Both total and solid particle number emissions were about 3 to 246 times higher during DPF regeneration compared to normal vehicle operation, with higher fractions of sub-10 nm solid particles. We showed that typical daily routes for goods movement operation in SCAB, especially the more urban routes, mostly occurred within disadvantaged communities, with minority populations and high indices for poverty, unemployment, and poor education. Our results indicated the vehicles spent a higher fraction of their total time within these areas at low speed and idling conditions, resulting in disproportionately higher exposures to ultrafine particles.