Evaluation of retrofit crankcase ventilation controls and diesel oxidation catalysts for reducing air pollution in school buses |
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| Authors: | Kim Trenbath Michael P Hannigan Jana B Milford |
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| Affiliation: | 1. Department of Atmospheric and Oceanic Sciences, 311 UCB, University of Colorado, Boulder, CO 80309, USA;2. Department of Mechanical Engineering, 427 UCB, University of Colorado, Boulder, CO 80309-0427, USA;1. Key Laboratory of Power Machinery and Engineering, Ministry of Education, Shanghai Jiao Tong University, Shanghai 200240, China;2. School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China;1. National Engineering Laboratory for Vacuum Metallurgy, Faculty of Metallurgical and Energy Engineering, Kunming University of Science and Technology, Kunming 650093, China;2. Engineering Research Center for Silicon Metallurgy and Silicon Materials of Yunnan Provincial Universities. Kunming 650093, China;3. State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou 310000, PR China;1. Department of Mathematics and Modeling, Saratov State Technical University, Politehnicheskaya 77, 410054, Saratov, Russian Federation;2. Department of Automation, Biomechanics and Mechatronics, Lodz University of Technology, 1/15 Stefanowskiego St., 90-924 Lodz, Poland;3. Cybernetic Institute, National Research Tomsk Polytechnic University, 634050 Tomsk, Lenin Avenue, 30, Russian Federation;4. Department of Applied Mathematics and Systems Analysis, Saratov State Technical University, 410054 Saratov, Politehnicheskaya 77, Russian Federation |
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| Abstract: | This study evaluates the effect of retrofit closed crankcase ventilation filters (CCFs) and diesel oxidation catalysts (DOCs) on the in-cabin air quality in transit-style diesel school buses. In-cabin pollution levels were measured on three buses from the Pueblo, CO District 70 fleet. Monitoring was conducted while buses were driven along their regular routes, with each bus tested three times before and three times after installation of control devices. Ultrafine number concentrations in the school bus cabins were 33–41% lower, on average, after the control devices were installed. Mean mass concentrations of particulate matter less than 2.5 μm in diameter (PM2.5) were 56% lower, organic carbon (OC) 41% lower, elemental carbon (EC) 85% lower, and formaldehyde 32% lower after control devices were installed. While carbon monoxide concentrations were low in all tests, mean concentrations were higher after control devices were installed than in pre-retrofit tests. Reductions in number, OC, and formaldehyde concentrations were statistically significant, but reductions in PM2.5 mass were not. Even with control devices installed, during some runs PM2.5 and OC concentrations in the bus cabins were elevated compared to ambient concentrations observed in the area. OC concentrations inside the bus cabins ranged from 22 to 58 μg m?3 before and 13 to 33 μg m?3 after control devices were installed. OC concentrations were correlated with particle-bound organic tracers for lubricating oil emissions (hopanes) and diesel fuel and tailpipe emissions (polycyclic aromatic hydrocarbons (PAH) and aliphatic hydrocarbons). Mean concentrations of hopanes, PAH, and aliphatic hydrocarbons were lower by 37, 50, and 43%, respectively, after the control devices were installed, suggesting that both CCFs and DOCs were effective at reducing in-cabin OC concentrations. |
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