Effects of Four Prototype Gasoline Particle Filters (GPFs) on Nanoparticle and Genotoxic PAH Emissions of a Gasoline Direct Injection (GDI) Vehicle

The fast replacement of traditional gasoline port-fuel injection technology with gasoline direct-injection (GDI) vehicles is expected to have a substantial impact on urban air quality. Herein we report on effects of four prototype gasoline particle filters (GPFs) on exhausts of a 1.6 L Euro-5 GDI vehicle. Two noncoated and two filters with catalytic coatings were investigated. These filters, on average, lowered PN emissions 4–7-fold to 4.0–6.8 × 10 11 particles/km. Genotoxic PAHs were lowered 2–5-fold too with GPF-1–3, with GPF-1 having the highest efficiency, 79% and resulting in 45 ng toxic equivalent concentration (TEQ)/km. Thus, particle filtration efficiencies and reduction of the genotoxic potentials are correlated. GPF-4 showing the poorest particle filtration efficiency (66–78%) also released exhausts with highest genotoxic potential of 240–530 ng TEQ/km. We recently reported particle-number (PN) emissions of four generations of GDI vehicles (Euro-3 to Euro-6) which released, on average, 2.5 × 10 12 ± 1.8 × 10 12 particles/km exceeding the current European limit of 6.0 × 10 11 particle/km. Thus, the implementation of filters to GDI vehicles requires best-available technology (BAT) with PN efficiencies >98% and catalytic activity, to avoid store-and-release of genotoxic PAHs. In-series applications of BAT-filters to GDI vehicles can lower genotoxic PAHs and soot nanoparticles.