Hydroxyl and hydroperoxyl radicals downwind of the exhaust emission indicates the importance of simulating the impact of road transportation on photochemistry at high spatial and temporal resolution. This offers a new perspective and measure for transportation fuel assessment. Accordingly, higher / exhaust emission, such as from diesel and M85, resulted in lower O3, not only locally but also downwind of the emission. These dispersion-box model simulations revealed a strong influence of atmospheric background balance between VOCs and nitrogen oxides (NOX = + ) on the impact of exhaust emissions on photochemistry, with higher tendency toward ozone (O3) formation or destruction for more VOC-limited or NOX-limited conditions, respectively. We used a heterogeneous chemical mechanism with 927 reactions and relatively detailed emission inventories to specifically meet the requirements for reliable simulation of the effect of exhaust emissions from vehicles fueled by selected model fuels- diesel, gasoline, and mixtures of 15% gasoline with 85% ethanol (E85) or 85% methanol (M85)-on photochemistry. Here we hypothesized that applying a chemical mechanism that is specifically developed according to both emission fractions and photochemical ozone creation potential of volatile organic compounds (VOCs) is key to gaining reliable insights into the impact of transportation fuels on photochemistry. This is mainly due to frequent use of lumped chemical mechanisms by related atmospheric modeling. Influence of conventional fuels-diesel and gasoline, and particularly ATFs on photochemical air pollution is not well-characterized, limiting assessments of ATFs and air quality. To enable use of this approach when data were unavailable, the fraction of the compound was determined based on the ratio of the compound's type (e.g., aromatic compound) in the emissions of gasoline and the alternative fuel ( Haskew and Liberty, 2011 Kelly et al., 1996bKelly et al.,, 1996aYanowitz and Mccormick, 2009).Īlternative transportation fuels (ATFs) can reduce air pollution. When data were available for the relative fraction of the emission of a particular compound out of all of the compounds, but not for its ratio compared to gasoline emission, the compound fraction was inserted into the model based on the ratio of total non-methane volatile organic compounds (NMVOCs) in the alternative fuel and gasoline ( Graham et al., S 2008 Haskew and Liberty, 2011 Kelly et al., 1999Kelly et al.,, 1996bKelly et al.,, 1996aYanowitz and Mccormick, 2009 Zhao et al., 2011) is the ratio between a specific compound and the total NMVOCs in the emission of the alternative fuel. About one-fifth of the compounds in the gasoline and diesel emissions were detailed for the alternative fuel emissions together with gasoline emission, enabling us to compare them directly and find their emission ratio.
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