Analysis of real-time variables affecting children's exposure to diesel-related pollutants during school bus commutes in Los Angeles

Sabin, Lisa D.; Kozawa, Kathleen; Behrentz, Eduardo; Winer, Arthur M.; Fitz, Dennis R.; Pankratz, David; Colome, Steven D.; Fruin, Scott

doi:10.1016/j.atmosenv.2005.05.037

Cited by 49 publications

(35 citation statements)

References 11 publications

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“…10 Those species are emitted to the atmosphere from natural and anthropogenic sources with an average global emission rate of anthropogenic carbon from fossil fuel combustion as high as 2.4 × 10 10 kg per year. 11 Once liberated into the ambient environment, PAHs and soot in respirable size of 10-100 nm can be transferred into the lungs by inhalation and are strongly implicated in the degradation of human health, 12 particularly due to their high carcinogenic risk potential. PAHs and carbonaceous nanoparticles are also serious water pollutants of marine ecosystems and bioaccumulate in the fatty tissue of living organisms.…”

Section: Introductionmentioning

confidence: 99%

Reaction Dynamics of Phenyl Radicals in Extreme Environments: A Crossed Molecular Beam Study

Kaiser

2008

Acc. Chem. Res.

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Polycyclic aromatic hydrocarbons (PAHs)sorganic compounds that consist of fused benzene ringssand their hydrogendeficient precursors have attracted extensive interest from combustion scientists, organic chemists, astronomers, and planetary scientists. On Earth, PAHs are toxic combustion products and a source of air pollution. In the interstellar medium, research suggests that PAHs play a role in unidentified infrared emission bands, diffuse interstellar bands, and the synthesis of precursor molecules to life. To build clean combustion devices and to understand the astrochemical evolution of the interstellar medium, it will be critical to understand the elementary reaction mechanisms under single collision conditions by which these molecules form in the gas phase.Until recently, this work had been hampered by the difficulty in preparing a large concentration of phenyl radicals, but the phenyl radical represents one of the most important radical species to trigger PAH formation in high-temperature environments. However, we have developed a method for producing these radical species and have undertaken a systematic experimental investigation. In this Account, we report on the chemical dynamics of the phenyl radical (C 6 H 5 ) reactions with the unsaturated hydrocarbons acetylene (C 2 H 2 ), ethylene (C 2 H 4 ), methylacetylene (CH 3 CCH), allene (H 2 CCCH 2 ), propylene (CH 3 CHCH 2 ), and benzene (C 6 H 6 ) utilizing the crossed molecular beams approach. For nonsymmetric reactants such as methylacetylene and propylene, steric effects and the larger cones of acceptance drive the addition of the phenyl radical to the nonsubstituted carbon atom of the hydrocarbon reactant. Reaction intermediates decomposed via atomic hydrogen loss pathways. In the phenyl-propylene system, the longer lifetime of the reaction intermediate yielded a more efficient energy randomization compared with the phenyl-methylacetylene system. Therefore, two reaction channels were open: hydrogen losses from the vinyl and from the methyl groups. All fragmentation pathways involved tight exit transition states. In the range of collision energies investigated, the reactions are dictated by phenyl radical addition-hydrogen atom elimination pathways. We did not observe ring closure processes with the benzene ring.Our investigations present an important step toward a systematic investigation of phenyl radical reactions under single collision conditions similar to those found in combustion flames and in high-temperature interstellar environments. Future experiments at lower collision energies may enhance the lifetimes of the reaction intermediates, which could open up competing ring closure channels to form bicyclic reaction products.

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Section: Introductionmentioning

confidence: 99%

Reaction Dynamics of Phenyl Radicals in Extreme Environments: A Crossed Molecular Beam Study

Kaiser

2008

Acc. Chem. Res.

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“…Route selected was found to be significantly affecting the PM 2.5 exposure levels for transport users as compared to the mode selected, and a combination of both the variables accounted for one-third of the exposure variation in a study having four different microenvironments that included bicycle, bus, car, and underground railway in London, UK [9]. Lead vehicle and type of test bus were observed to be the influential factors affecting in-vehicle pollutant levels when the windows are opened and closed respectively after considering the exposure to black carbon, particle bound polycyclic aromatic hydrocarbons, and nitrogen dioxide in school buses in Los Angeles [10]. Relationships for indoor air quality were developed using regression analysis for CO 2 , CO, SO 2 , and PM in public transport buses operating in Toledo, Ohio [11].…”

Section: Introductionmentioning

confidence: 99%

“…It has been documented that motor vehicles produce about 1.538 trillion kilograms of carbon dioxide (CO 2 ) emissions and the road transportation sector contributes about 56% of total carbon monoxide (CO) emissions, 38% of total nitrogen oxides (NO x ), 2% of particulate matter less than 2.5 micrometer (PM 2.5 ), 1% of particulate matter less than 10.0 micrometer (PM 10.0 ), 23% of volatile organic compounds (VOCs), and 2% of total sulfur dioxide (SO 2 ) [2]. Over the years, vehicular usage has been increasing rapidly in combination with a booming growth in population.…”

Section: Introductionmentioning

confidence: 99%

Study of In-Vehicle Pollutant Variation in Public Transport Buses Operating on Alternative Fuels in the City of Toledo, Ohio

Kadiyala¹

2011

TOEBMJ

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This study focuses on determining the variation of indoor pollutants in public transport buses in the City of Toledo running on biodiesel (BD) and ultra low sulfur diesel (ULSD). The indoor pollutants monitored are carbon dioxide (CO 2 ), carbon monoxide (CO), sulfur dioxide (SO 2 ), nitric oxide (NO), and particulate matter (PM). Temperature (Temp.) and relative humidity (RH) are also measured inside the vehicle in addition to the monitored in-vehicle pollutants. The various factors generally affecting indoor air quality in any microenvironment are indoor sources of pollutants (people, furniture, etc.), ventilation, outdoor air quality, meteorology, pollutant decay, and vehicular traffic. The objective of this research paper is to study the daily, monthly, and seasonal variation of in-vehicle pollutants in relation to different variables and also determine the statistical significance of in-vehicle pollutant levels in biodiesel and ultra low sulfur diesel buses. The daily, monthly, and seasonal variations of the pollutants monitored are studied and it was observed that the pollutant level buildup within a bus compartment is due to a combination of different factors and not a result of variation due to a single variable.CO 2 levels are influenced by a combination of varying passenger ridership, vehicular traffic, ventilation settings, and bus status. CO and SO 2 levels depend on vehicular traffic, ventilation settings, and to an extent on vehicle speed. NO levels varied with vehicular traffic and ventilation settings. PM levels are influenced by vehicular traffic, ventilation settings and vehicle speed. Relatively higher pollutant concentrations are observed for the majority of pollutants in winter months when there is not much air exchange in the bus compartment. A study of the trends revealed that the concentrations were mainly influenced by peak hours, ventilation settings, vehicular traffic, passenger ridership, and meteorology. The pollutant levels of CO 2 and SO 2 are found to be statistically significantly higher in an ultra low sulfur diesel bus while the pollutant levels of CO, NO, and particle numbers with size range between 0.30 m and 0.40 m are found to be statistically significantly higher in a biodiesel bus. Particulate matter concentrations are found to be statistically similar in both the test buses.

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“…These air pollutant sensors can perform real-time monitoring at several monitoring points along a road network. SPM has recently been recognized as an air pollutant that has a causal correlation with the human fatality rate (Sabin et al, 2005), and NO2 is recognized as an air pollutant that causes respiratory illness (Smith et al, 2000). In conventional studies, air pollutant amounts are measured with passive samplers that require very longer measurement periods of up to a month, and no dynamic validation has been conducted in real time.…”

Section: Introductionmentioning

confidence: 99%

Development of Real-Time Sensing Network and Simulation on Air Pollution and Transport

Maruo¹,

Sugiyama²

2012

Air Quality - New Perspective

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Analysis of real-time variables affecting children's exposure to diesel-related pollutants during school bus commutes in Los Angeles

Cited by 49 publications

References 11 publications

Reaction Dynamics of Phenyl Radicals in Extreme Environments: A Crossed Molecular Beam Study

Reaction Dynamics of Phenyl Radicals in Extreme Environments: A Crossed Molecular Beam Study

Study of In-Vehicle Pollutant Variation in Public Transport Buses Operating on Alternative Fuels in the City of Toledo, Ohio

Development of Real-Time Sensing Network and Simulation on Air Pollution and Transport

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