Renewable diesel fuels and emission control strategies : Implications for occupational exposure, human health, and the environment

Combustion of fossil diesel is a major environmental problem for both the climate and human health. Renewable diesel fuels have been developed and introduced to the market to reduce the net CO2 emissions. Emission control strategies, such as aftertreatment systems, have been implemented to reduce the health hazardous particulate matter (PM) and nitrogen oxides (NOx) emissions. The overall aim of this thesis was to understand the effect of introducing renewable diesel fuels and emission abatement techniques on health relevant exhaust emissions. Laboratory studies were performed to assess the primary and secondary emissions from a heavy-duty diesel engine fueled by the renewable diesel fuels HVO (hydrotreated vegetable oil) and RME (rapeseed methyl ester).The emissions were characterized by detailed particle and gas measurements. We also evaluated the effect of using an aftertreatment system consisting of a diesel oxidation catalyst (DOC) and a diesel particle filter (DPF) on the exhaust emissions. The occupational exposure to diesel exhaust from vehicles in a Swedish modern underground mine was quantified and evaluated in relation to the vehicles’ level of emission reduction technology. The underground ambient concentrations were quantified, and real-world emission factors were calculated. The short-term health effects of HVO exhaust from modern non-road vehicles (2019), with or without the PM fraction, were investigated in a controlled human exposure chamber study. Replacing fossil diesel with HVO and RME significantly reduced the PM emissions, especially the soot emissions(measured as elemental carbon [EC] and equivalent black carbon [eBC]). The fuel change also reduced the hydrocarbon and carbon monoxide emissions, particularly from RME. The significantly reduced hydrocarbon emissions from RME also reduced the secondary aerosol formation, and thus potentially reducing the total atmospheric particle mass burden. Aftertreatment systems containing both a DOC and DPF were very efficient in removing the particle concentrations in the laboratory studies for all fuels. However, as long as a large portion of the vehicle fleet does not have any PM removal systems, the usage of HVO and RME will have a positive impact on overall PM reductions. The average occupational exposure concentration of EC was 7 μg m-3 in the underground mine. This is much lower than the future EU occupational exposure limit (OEL) for diesel exhaust (50 μg EC m-3, from 2026underground). However, epidemiological studies suggest health-based limits closer to 1 μg m-3, which indicates that we should aim to further reduce the exposure. The measured EC exposures ware reduced in areas where vehicles had DPFs. Short-term exposure to HVO exhaust below the EU OELs did not cause severe pulmonary function changes in healthy subjects. However, the subjects experienced an increase in self-rated mild irritation symptoms, and a mild decrease in nasal patency after both the particle-laden and the particle-free HVO exposure. This may indicate irritative effects from exposure to HVO exhaust from modern non-road vehicles below future OELs. Air pollution from combustion sources (not only from vehicles) is a global problem that will be present for years to come. Due to the many adverse effects linked to aerosol air pollution, measures need to be taken to reduce the particle exposures in environmental and occupational settings. The future occupational exposure limit of 50 μg ECm-3 is still much higher than proposed health-based limits. For combustion vehicles, the most efficient way to reduce EC emissions is by using aftertreatment systems focused on removing the PM, such as DPFs. Resources need to be focused on ensuring that such systems are in place and working effectively in all combustion vehicles. This is especially the case in highly exposed areas such as in cities and enclosed work environments

Fire-induced radiological integrated assessment : aerosol characterization

This report on detailed aerosol characterization of fire smoke emissions is part of the Fire-Induced Radiological Integrated Assessment (FIRIA; CERN, Switzerland). In this study, carried out at Lund University, a number of materials were combusted in a cone calorimeter at varied heat fluxes. In a few experiments, the effect of reduced O2 content of supply air was investigated (vitiated conditions). The materials included electrical components, magnets, plastic components, oil and cables and were selected due to their high probability of experiencing ionizing radiation in the research facilities at CERN. The aerosol particle yield in the combustion emissions was determined in terms of number and mass emissions. In addition, the particle physical properties in terms of size distributions, the mass - mobility relationship, and the black carbon fraction of emitted particles was determined. Finally, the particle morphology was determined with transmission electron microscopy (TEM) and elemental composition of trace elements by ICP-MS. The total range of aerosol mass yields spanned from approximately 0.005 (g/g fuel) to 0.23 (g/g fuel). Electrical components and magnets were identified as the combustibles with highest mass yields. Mass yields for cables spanned from 0.005-0.09 g/g fuel. The emissions were highly dynamic, with rapid shifts in concentrations and the particle number size distribution as measured with a fast mobility spectrometer (DMS500). The number yields ranged from approximately 0.05*10^14 to 2*10^14 emitted particles per gram of fuel and was measured within the size range 5-1000 nm. The emissions could be parameterized for future modelling applications into nucleation mode particles (with geometric mean diameter that varied between 20-50 nm) and accumulation mode particles (with geometric mean diameter 100-230 nm). The aerosol mass yields were governed primarily by the concentration and size distribution of accumulation mode particles. Mass yields were determined from 1) Impactor measurements (Dekati Gravimetric Impactor) and 2) Simultaneous measurements of the electrical mobility size distribution (DMS500) and effective density distribution (DMA-APM). The general agreement between the two techniques was good (R2=0.93). Black carbon is indicative of refractory carbonaceous particles which form in fuel rich conditions of the hot flame environment and associated with the black color of soot (smoke). Black carbon yields were for most experiments similar to the derived mass yields. TEM images showed typical refractory black carbon aggregates at high BC fractions. The primary particle size was larger than for diesel exhaust. However, at reduced heat flux and during vitiated combustion (reduced O2 concentration), black carbon yields were sometimes much lower than the derived particle mass yields. TEM analysis for a sample with low BC fraction showed only very few particles and those that were found had distinctly different properties to the high BC fraction sample. We hypothesize that particles emitted under these conditions were dominated by low volatility organic matter formed in the pyrolysis of the materials. Such components were likely co-emitted with black carbon also in conventional experiments, although in minor mass fractions. Based on previous studies it can be hypothesized that H:C ratios are low for the cases with high BC fraction

Clinical Manifestations of the <em>Epsilonproteobacteria</em> (<em>Helicobacter pylori</em>)

Epsilonproteobacteria is a large group of Gram-negative curved or spiral microaerophilic rods, of which many are difficult to culture. Because this group of bacteria is not very well investigated, our knowledge about them is limited, and a great amount of research is still needed. At least two species are well-established human pathogens: Campylobacter jejuni/coli causing gastroenteritis and Helicobacter pylori causing gastric and extra-gastric manifestations. It is well accepted that H. pylori causes a chronic inflammation in the stomach and thereby causes H. pylori-associated gastritis, which may or may not be symptomatic. The association between H. pylori and peptic ulcers, MALT lymphomas, gastric cancer, idiopathic thrombocytopenic purpura, and unexplained iron-deficiency anemia (IDA) is strongly evidence based. On the other hand, pernicious (vitamin B12 deficiency) anemia, neuromyelitis optica, asthma, and Graves’ disease are less evidence based. H. pylori may also be associated with cardiovascular disease, pancreatitis, pancreatic cancer, obesity, diabetes mellitus type 2, Parkinson’s disease, liver diseases, and preeclampsia. H. pylori is thus involved in many gastric and extra-gastric manifestations either directly or indirectly by several proposed mechanisms including antigenic mimicry

Interfaces in complex InAs-GaSb heterostructured nanowires - A transmission electron microscopy study

In this project epitaxially grown InAs-GaSb complex heterostructured nanowires have been characterized by means of aberration corrected TEM techniques and energy dispersive X-ray spectroscopy (EDX). The InAs-GaSb material is of interest due to its high charge carrier mobility, which has possible applications in electronic devices such as FETs. InAs-GaSb heterostructured nanowires in zincblende structure have previously been studied and have possible electronic applications such as tunneling field effect transistors. However, heterostructured nanowires of InAs-GaSb in wurtzite structure have until now not been observed. The focus of this project have been to perform a structural characterization of InAs-GaSb core-shell and InAs-GaSb-InAs core-shell-shell nanowires with an emphasis on the interfaces. Epitaxial axial growths of GaSb are present on top of the core-shell(-shell) structures which are induced by the seed particles during the shell growth. The lattice mismatch of wurtzite InAs-GaSb is 1.15%. However, the nanowire shells were fully epitaxial with practically no misfit dislocations. This is due to that the elastic relaxation mechanisms are the dominating mechanisms for compensating the lattice mismatch induced strain. As the shells were fully epitaxial stacking faults are transferred from the core to the shells. The tapering events of the shells were found to generally coincide with these stacking faults. Analysis with high resolution EDX revealed a change of composition at the axial interface between the InAs core and the axial growth of GaSb. A short segment, approx. 6 nm, of GaAsSb ternary at the axial interface is attributed to the different solubility of the elements in the Au seed particle and to the reservoir effect of the seed particle during epitaxial growth. A one atomic bilayer thick composition change was present at the radial interfaces, which was observed by means of aberration corrected scanning TEM (STEM). The bilayer was a ternary of InAsGa between the InAs core and the GaSb shell. Such bilayers were present also at both interfaces in the GaSb-InAs double shell nanowires. This change in composition might influence the band gap alignment and subsequently the electric properties of the material. It is of importance to further evaluate the functional impact of this ternary in order to further understand and develop core-shell materials. Evidence of metastability of the core-shell nanowires were also found during the project which is another important phenomenon to further investigate

Investigation of Particle Number Emission Characteristics in a Heavy-Duty Compression Ignition Engine Fueled with Hydrotreated Vegetable Oil (HVO)

Diesel engines are one of the most important power generating units these days. Increasing greenhouse gas emissions level and the need for energy security has prompted increasing research into alternative fuels for diesel engines. Biodiesel is the most popular amongst the alternatives for diesel fuel as it is biodegradable, renewable and can be produced domestically from vegetable oils. In recent years, hydro-treated vegetable oil (HVO) has also gained popularity due to some of its advantages over biodiesel such as higher cetane number, lower deposit formation, storage stability etc. HVO is a renewable, paraffinic biobased alternative fuel for diesel engines similar to biodiesel. Unlike biodiesel, the production process for HVO involves hydrogen as catalyst instead of methanol which removes oxygen content from vegetable oil. A modified 6-cylinder heavy-duty diesel engine (modified for operation with single cylinder) was used for studying particle number emission characteristics for HVO fuel. The investigation was performed for varying fuel injection pressure at various engine operating loads (6, 8, 10, 12 and 14 bar IMEP). Five rail pressures were chosen from 800 to 2000 bar at a step of 300 bar. The results show that increase in rail pressure tends to increase nucleation mode particle number concentration (quantify the increase) while increase in engine load results in higher total particle number concentration. No significant differences were observed in soot and oxides of nitrogen (NOx) emission for HVO compared to mineral diesel. The fraction of emitted particles in the nucleation mode was observed to increase with increasing fuel injection pressure

Acute Cardiovascular Effects of Hydrotreated Vegetable Oil Exhaust

Ambient air pollution is recognized as a key risk factor for cardiovascular morbidity and mortality contributing to the global disease burden. The use of renewable diesel fuels, such as hydrotreated vegetable oil (HVO), have increased in recent years and its impact on human health are not completely known. The present study investigated changes in cardiovascular tone in response to exposure to diluted HVO exhaust. The study participants, 19 healthy volunteers, were exposed in a chamber on four separate occasions for 3 h and in a randomized order to: (1) HVO exhaust from a wheel loader without exhaust aftertreatment, (2) HVO exhaust from a wheel loader with an aftertreatment system, (3) clean air enriched with dry NaCl salt particles, and (4) clean air. Synchronized electrocardiogram (ECG) and photoplethysmogram (PPG) signals were recorded throughout the exposure sessions. Pulse decomposition analysis (PDA) was applied to characterize PPG pulse morphology, and heart rate variability (HRV) indexes as well as pulse transit time (PTT) indexes were computed. Relative changes of PDA features, HRV features and PTT features at 1, 2, and 3 h after onset of the exposure was obtained for each participant and exposure session. The PDA index A13, reflecting vascular compliance, increased significantly in both HVO exposure sessions but not in the clean air or NaCl exposure sessions. However, the individual variation was large and the differences between exposure sessions were not statistically significant

Biomarkers after Controlled Inhalation Exposure to Exhaust from Hydrogenated Vegetable Oil (HVO)

Hydrogenated vegetable oil (HVO) is a renewable diesel fuel used to replace petroleum diesel. The organic compounds in HVO are poorly characterized; therefore, toxicological properties could be different from petroleum diesel exhaust. The aim of this study was to evaluate the exposure and effective biomarkers in 18 individuals after short-term (3 h) exposure to HVO exhaust and petroleum diesel exhaust fumes. Liquid chromatography tandem mass spectrometry was used to analyze urinary biomarkers. A proximity extension assay was used for the measurement of inflammatory proteins in plasma samples. Short-term (3 h) exposure to HVO exhaust (PM1 similar to 1 mu g/m(3) and similar to 90 mu g/m(3) for vehicles with and without exhaust aftertreatment systems, respectively) did not increase any exposure biomarker, whereas petroleum diesel exhaust (PM1 similar to 300 mu g/m(3)) increased urinary 4-MHA, a biomarker for p-xylene. HVO exhaust from the vehicle without exhaust aftertreatment system increased urinary 4-HNE-MA, a biomarker for lipid peroxidation, from 64 ng/mL urine (before exposure) to 141 ng/mL (24 h after exposure, p < 0.001). There was no differential expression of plasma inflammatory proteins between the HVO exhaust and control exposure group. In conclusion, short-term exposure to low concentrations of HVO exhaust did not increase urinary exposure biomarkers, but caused a slight increase in lipid peroxidation associated with the particle fraction

Identification and characterization of design fires and particle emissions to be used in performance-based fire design of nuclear facilities

CERN operates one of the most complex particle accelerator facilities in the world. Several different hazards, including fires, are present and need to be investigated and reduced to a tolerable level. Toward this goal, CERN aims at developing a catalog containing detailed fire dynamics descriptions of combustible items present in its facilities. This paper contributes to this catalog in two ways. First, through the development of a design fire calculator for electrical cabinets that allows the determination of potential design fire curves for any number of electrical cabinets/racks. The second contribution was to experimentally characterize the smoke production rates and smoke particle properties of the most common cables and insulating oils used at CERN by coupling a fast particle mobility analyzer to a cone calorimeter. The two particle size modes (accumulation and nucleation mode) could be linked to the fire properties and heat release rate. Accumulation mode particles (~200 nm) were associated with high heat release rates and high soot emissions from the flame. This study identifies a necessity to consider ultrafine particle emissions with low mass emissions but high number emissions in relation to risk assessments pertaining to nuclear facilities and dispersion of radioactive aerosols to the surrounding environment

Underground emissions and miners' personal exposure to diesel and renewable diesel exhaust in a Swedish iron ore mine

PURPOSE: Underground diesel exhaust exposure is an occupational health risk. It is not known how recent intensified emission legislation and use of renewable fuels have reduced or altered occupational exposures. We characterized these effects on multipollutant personal exposure to diesel exhaust and underground ambient air concentrations in an underground iron ore mine.METHODS: Full-shift personal sampling (12 workers) of elemental carbon (EC), nitrogen dioxide (NO2), polycyclic aromatic hydrocarbons (PAHs), and equivalent black carbon (eBC) was performed. The study used and validated eBC as an online proxy for occupational exposure to EC. Ambient air sampling of these pollutants and particle number size distribution and concentration were performed in the vicinity of the workers. Urine samples (27 workers) were collected after 8 h exposure and analyzed for PAH metabolites and effect biomarkers (8-oxodG for DNA oxidative damage, 4-HNE-MA for lipid peroxidation, 3-HPMA for acrolein).RESULTS: The personal exposures (geometric mean; GM) of the participating miners were 7 µg EC m-3 and 153 µg NO2 m-3, which are below the EU occupational exposure limits. However, exposures up to 94 µg EC m-3 and 1200 µg NO2 m-3 were observed. There was a tendency that the operators of vehicles complying with sharpened emission legislation had lower exposure of EC. eBC and NO2 correlated with EC, R = 0.94 and R = 0.66, respectively. No correlation was found between EC and the sum of 16 priority PAHs (GM 1790 ng m-3). Ratios between personal exposures and ambient concentrations were similar and close to 1 for EC and NO2, but significantly higher for PAHs. Semi-volatile PAHs may not be effectively reduced by the aftertreatment systems, and ambient area sampling did not predict the personal airborne PAHs exposure well, neither did the slightly elevated concentration of urinary PAH metabolites correlate with airborne PAH exposure.CONCLUSION: Miners' exposures to EC and NO2 were lower than those in older studies indicating the effect of sharpened emission legislation and new technologies. Using modern vehicles with diesel particulate filter (DPF) may have contributed to the lower ambient underground PM concentration and exposures. The semi-volatile behavior of the PAHs might have led to inefficient removal in the engines aftertreatment systems and delayed removal by the workplace ventilation system due to partitioning to indoor surfaces. The results indicate that secondary emissions can be an important source of gaseous PAH exposure in the mine

Fresh and Aged Organic Aerosol Emissions from Renewable Diesel-Like Fuels HVO and RME in a Heavy-Duty Compression Ignition Engine

A modern diesel engine is a reliable and efficient mean of producing power. A way to reduce harmful exhaust and greenhouse gas (GHG) emissions and secure the sources of energy is to develop technology for an efficient diesel engine operation independent of fossil fuels. Renewable diesel fuels are compatible with diesel engines without any major modifications. Rapeseed oil methyl esters (RME) and other fatty acid methyl esters (FAME) are commonly used in low level blends with diesel. Lately, hydrotreated vegetable oil (HVO) produced from vegetable oil and waste fat has found its way into the automotive market, being approved for use in diesel engines by several leading vehicle manufacturers, either in its pure form or in a mixture with the fossil diesel to improve the overall environmental footprint. There is a lack of data on how renewable fuels change the semi-volatile organic fraction of exhaust emissions. In order to characterize and explain the difference in exhaust emissions from fossil diesel, HVO and RME fuels, particulate matter (PM) emissions were sampled at two exhaust positions of an experimental single cylinder Scania D13 heavy-duty (HD) diesel engine: at the exhaust manifold, and after a diesel oxidation catalyst (DOC). Advanced analyzing techniques were used to characterize the composition of the organic PM. Special attention was paid to an operating point at 18% intake oxygen level with constant engine operating conditions where the emission level of nitrogen oxides (NOx) was low, and carbon monoxide (CO) and total hydrocarbon (THC) were relatively low. On-line aerosol mass spectrometry (AMS) suggests that the chemical composition of the organic aerosols (OAs) was similar for HVO and diesel. However, RME both reduced the OA emissions and changed the composition with evidence for fuel signatures in the mass spectra. When the emissions were aged in an oxidation flow reactor to simulate secondary organic aerosol (SOA) formation in the atmosphere, it was found that OA concentration strongly increased for all fuels. However, SOA formation was substantially lower for RME compared to the other fuels. The DOC strongly reduced primary organic emissions in both the gas (THC) and particle phase (OA) and only marginally affected OA composition. The DOC was also effective in reducing secondary organic aerosol formation upon atmospheric aging