[en] On-road vehicular emissions contribute to the formation of fine particulate matter and ozone which can lead to increased adverse health outcomes near the emission source and downwind. In this study, we present a transportation-specific modeling platform utilizing the community multiscale air quality model (CMAQ) with the decoupled direct method (DDM) to estimate the air quality and health impacts of on-road vehicular emissions from five vehicles classes; light-duty autos, light-duty trucks (LDT), medium-duty trucks, heavy-duty trucks (HDT), and buses (BUS), on PM_2.5 and O₃ concentrations at a 12 × 12 kilometer scale for 12 states and Washington D.C. as well as four large metropolitan statistical areas in the Northeast and Mid-Atlantic U.S. in 2016. CMAQ-DDM allows for the quantification of sensitivities from individual precursor emissions (NO${}_{\mathrm{X}}$, SO₂, NH₃, volatile organic compounds, and PM_2.5) in each state to pollution levels and health effects in downwind states. In the region we considered, LDT are responsible for the most PM_2.5-attributable premature mortalities at 1234 with 46% and 26% of those mortalities from directly emitted primary particulate matter and NH₃, respectively; and O₃-attributable premature mortalities at 1129 with 80% of those mortalities from NO${}_{\mathrm{X}}$ emissions. Based on a detailed source-receptor matrix of sensitivities with subsequent monetization of damages that we computed, we find that the largest damages-per-ton estimate is approximately $4 million per ton of directly emitted primary particulate matter from BUS in the New York-Newark-Jersey City metropolitan statistical area. We find that on-road vehicular NH₃ emissions are the second largest contributor to PM_2.5 concentrations and health impacts in the study region, and that reducing 1 ton of NH₃ emissions from LDT is ∼75 times and from HDT is ∼90 times greater in terms of damages reductions than a 1 ton reduction of NO${}_{\mathrm{X}}$. By quantifying the impacts by each combination of source region, vehicle class, and emissions precursor this study allows for a comprehensive understanding of the largest vehicular sources of air quality-related premature mortalities in a heavily populated part of the U.S. and can inform future policies aimed at reducing those impacts. (paper)

[en] Highlights: • Sensitivities can help to determine distinct chemical regimes. • Aircraft NOx emissions contribute most to nonlinear chemistry. • Higher order sensitivities not needed for aircraft emission reduction strategies. • Novel approach to determine emissions sector contribution to attainment designations. In this study we utilize the Decoupled Direct Method (HDDM-3D) as implemented in the Community Multiscale Air Quality Model (CMAQ) to calculate first and second order sensitivity coefficients of O₃ and PM_2.5 concentrations with respect to aviation emissions during landing and takeoff (LTO) cycles at ten individual airports; five located in regions of attainment of O₃ and PM_2.5 NAAQS: Boston Logan (BOS), Kansas City (MCI), Raleigh-Durham (RDU), Seattle-Tacoma (SEA), and Tucson (TUS); and five airports in current nonattainment areas: Chicago O'Hare (ORD), Hartsfield- Jackson Atlanta (ATL), New York John F. Kennedy (JFK), Los Angeles (LAX), and Charlotte- Douglas (CLT). We utilize these coefficients in an attainment/nonattainment emission decrease/increase analysis to determine the importance of including second order sensitivity coefficients for quantifying O₃ and PM_2.5 concentration responses to LTO aircraft emission reductions near the airport. Sensitivity coefficients help to determine distinct chemical regimes, NO_X-limited versus NO_X-inhibited for the case of O₃ formation, and NH₃-rich versus NH₃-poor for the case of PM_2.5 formation. Overall, we find that NO_X LTO emissions are the largest contributor to any potential nonlinearity in O₃ and PM_2.5 formation through LTO emissions. However, when utilizing Taylor series expansions to estimate O₃ and PM_2.5 concentration responses under LTO emission perturbation scenarios, differences in responses calculated using only first order coefficients and responses calculated using both first and second order coefficients were less than 1% for LTO emission perturbations less than 100%. Hence, we find from the results in this study that first order sensitivity coefficients are sufficient for constructing accurate LTO emissions perturbation scenarios. This study also demonstrates through the analyses performed, an illustration of how HDDM-based sensitivity calculations can be used to assess sector-specific impacts on attainment designations.

[en] The theoretical description of sparse matter attracts much interest, in particular for those ground-state properties that can be described by density functional theory. One proposed approach, the van der Waals density functional (vdW-DF) method, rests on strong physical foundations and offers simple yet accurate and robust functionals. A very recent functional within this method called vdW-DF-cx [K. Berland and P. Hyldgaard, Phys. Rev. B 89, 035412 (2014)] stands out in its attempt to use an exchange energy derived from the same plasmon-based theory from which the nonlocal correlation energy was derived. Encouraged by its good performance for solids, layered materials, and aromatic molecules, we apply it to several systems that are characterized by competing interactions. These include the ferroelectric response in PbTiO₃, the adsorption of small molecules within metal-organic frameworks, the graphite/diamond phase transition, and the adsorption of an aromatic-molecule on the Ag(111) surface. Our results indicate that vdW-DF-cx is overall well suited to tackle these challenging systems. In addition to being a competitive density functional for sparse matter, the vdW-DF-cx construction presents a more robust general-purpose functional that could be applied to a range of materials problems with a variety of competing interactions