title: Near-road modeling and measurement of cerium-containing particles generated by nanoparticle diesel fuel additive use.
abstract: Cerium oxide nanoparticles (nCe) are used as a fuel-borne catalyst in diesel engines to reduce particulate emissions, yet the environmental and human health impacts of the exhaust particles are not well understood. To bridge the gap between emission measurements and ambient impacts, size-resolved measurements of particle composition and mass concentration have been performed in Newcastle-upon-Tyne, United Kingdom, where buses have used an nCe additive since 2005. These observations show that the noncrustal cerium fraction thought to be associated with the use of nCe has a mass concentration ∼ 0.3 ng m(-3) with a size distribution peaking at 100-320 nm in aerodynamic diameter. Simulations with a near-roadway multicomponent sectional aerosol dynamic model predict that the use of nCe additives increases the number concentration of nuclei mode particles (<50 nm in diameter) while decreasing the total mass concentration. The near-road model predicts a downwind mass size distribution of cerium-containing particles peaking at 150 nm in aerodynamic diameter, a value similar to that measured for noncrustal cerium in Newcastle. This work shows that both the emission and atmospheric transformation of cerium-containing particles needs to be taken into account by regional modelers, exposure scientists, and policymakers when determining potential environmental and human health impacts.
authors.affiliation: National Exposure Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency , Research Triangle Park, North Carolina 27711, United States.
authors.forename: Brett
authors.initials: B
authors.lastname: Gantt
authors.forename: Shamia
authors.initials: S
authors.lastname: Hoque
authors.forename: Robert D
authors.initials: RD
authors.lastname: Willis
authors.forename: Kathleen M
authors.initials: KM
authors.lastname: Fahey
authors.forename: Juana Mari
authors.initials: JM
authors.lastname: Delgado-Saborit
authors.forename: Roy M
authors.initials: RM
authors.lastname: Harrison
authors.forename: Garnet B
authors.initials: GB
authors.lastname: Erdakos
authors.forename: Prakash V
authors.initials: PV
authors.lastname: Bhave
authors.forename: K Max
authors.initials: KM
authors.lastname: Zhang
authors.forename: Kasey
authors.initials: K
authors.lastname: Kovalcik
authors.forename: Havala O T
authors.initials: HO
authors.lastname: Pye
mesh_terms: D000336:Aerosols; D000393:Air Pollutants / Q000032:analysis*; D002563:Cerium / Q000032:analysis*; D004784:Environmental Monitoring / Q000379:methods*; D005742:Gasoline / Q000032:analysis*; D006801:Humans; D008962:Models, Theoretical; D018986:Motor Vehicles; D053758:Nanoparticles; D010316:Particle Size; D052638:Particulate Matter / Q000032:analysis*; D006113:United Kingdom; D001335:Vehicle Emissions / Q000032:analysis*
chemical_list: D000336:Aerosols; D000393:Air Pollutants; D005742:Gasoline; D052638:Particulate Matter; D001335:Vehicle Emissions; D002563:Cerium; C030583:ceric oxide