Exhaust Particulate Matter Emissions Research Articles

Assessment of vehicle exhaust PM emissions using high-resolution on-road measurements in Seoul, Korea

In megacities, road traffic is a major source of particulate matter (PM), requiring a critical understanding of effective air pollution control. Despite existing methods to determine PM emission factors (EFs) of vehicles, accurate estimation of PM emissions under real driving conditions remains challenging. We aimed to assess the EFs of organic aerosol (OA) and equivalent black carbon (eBC) from vehicles through on-road measurements in Seoul, Korea, to understand real-world PM emissions. We used a mobile laboratory equipped with an aerosol mass spectrometer and an aethalometer to measure the composition of PM. On-road measurements were conducted in vehicle tunnels, urban roadways, and residential areas, and the characteristics of measurement points were compared and analyzed. Our results showed that concentrations of OA increased proportionally with the influence of vehicle exhaust, while oxidation states of the OA decreased. Mobile measurements revealed spatial heterogeneities in aerosols, highlighting distinct characteristics of fresh OA on vehicle roads and elevated oxidation state values in residential areas. Active nitrate formation near vehicles led to elevated NO3 concentrations on roads compared to residential areas. Our study shows that mobile PM measurements, including OA and eBC, are valuable for the direct evaluation of emission inventories. However, given that the calculated EFs may not be applicable to other cities due to differences in vehicle composition and traffic conditions, the development of city-specific EFs will be necessary in the future. Furthermore, it is recommended to integrate this methodology with conventional emission inventories to identify vehicle-type-specific emissions.Graphical

Experimental study of particulate matter emission for a diesel engine fueled with nanoparticles and biofuel / diesel blends

There has been a lot of interest in alternative fuels due to the depletion of petroleum supplies and growing environmental concerns. Biodiesel is made from renewable resources and is one of the many practical and beneficial fuel substitutes for fossil fuels. Recent advancements in nanotechnology have made it feasible to use nanoparticles as fuel additives for internal combustion engines. An earlier study suggested that these compounds might enhance engine performance. There has been a concern that this may increase the particulate matter emitted with the exhaust which adversely affects the air quality. The size-distribution of unregulated particulate matter (PM) emitted with exhaust gases is examined in this work. Under various load conditions, PM exhaust emissions were examined while keeping the engine running at a constant 1350 rpm. A nanoparticles of 50 parts per milligram of Aluminum oxide Al2O3 and Iron oxide Fe2O3 into the jatropha biodiesel / diesel fuel blend. When the engine is fueled with blend of diesel, biodiesel, and nanoparticles ternary fuel, it created fewer particulate matter emissions than the diesel/biodiesel binary blend which contains no nanoparticles. In comparison to pure diesel fuel, the diesel/biodiesel blend binary combination produced 10–15 % less PM1, PM2.5, PM7, and PM10 emissions which is very critical to air pollution problem with the fine/very fine particles.

Tracer-Gas-Integrated Measurements of Brake-Wear Particulate Matter Emissions from Heavy-Duty Vehicles.

Automotive brake-wear emissions are increasingly important in on-road particulate matter (PM) emission inventory. Previous studies reported a high level of PM emissions from the friction materials of light/medium-duty vehicles, but there are few data available from heavy-duty (HD) vehicles equipped with drum brakes despite their popularity (∼85% in HD vehicle fleet). This study developed a novel tracer-gas-integrated method for brake-wear PM emission measurements and evaluated four HD vehicles on a chassis dynamometer that complied with regulatory exhaust emission testing requirements. Three class-6 vehicles with a similar test weight demonstrated repeatability, with the coefficient of variation in the range of 9-36%. Braking events increased PM concentrations by 3 orders of magnitude above the background level. Resuspension of brake-wear PM also occurred during acceleration and contributed to 8-31% of the total PM2.5 mass. The class-6 vehicles had PM2.5 emissions from a single brake (0.7-1.5 mg/km/brake), generally similar to the level of tail-pipe exhaust PM emissions (0.7-1.5 mg/km/vehicle) of each vehicle. A class-8 vehicle exhibited brake-wear PM2.5 emissions (2.4-3.4 mg/km/brake) significantly higher than the tail-pipe exhaust PM emissions (∼1.3 mg/km/vehicle). This article reports an exceptionally high level of brake-wear PM emissions measured directly from the drum brakes of HD vehicles.

Experimental Investigations on Control of Exhaust Emissions of a Semi-Adiabatic Diesel Engine with Plastic Oil

This paper concentrates on alternative fuel technology for diesel engine and environmental protection. The exhaust emissions from diesel engine cause severe health hazards when they are inhaled in.. They also cause environmental disorders. Hence control of these emissions is an immediate step. Vegetable oils and alcohols are important substitutes for diesel fuel, as they are renewable in nature. Though vegetable oils have comparable properties with diesel fuel, they have high viscosity and low volatility causing combustion problems in diesel engines. Alcohols have high volatility but low Cetane number (a measure of combustion quality in diesel engine). Plastic oil derived from waste plastic by the process of pyrolysis has equitant calorific value with diesel fuel. However, its viscosity is higher than diesel fuel calls for semi adiabatic diesel engine (SADE). The concept of semi adiabatic diesel engine is to reduce heat flow to the coolant there by providing hot combustion chamber used for burning high viscous fuels like plastic oil. Semi adiabatic engine consisted of air gap insulated piston with stainless steel crown and stainless steel gasket. The exhaust emissionsof particulate matter (PM), carbon monoxide (CO), nitrogen oxide levels (NOx ) and Un-burnt hydrocarbons (UBHC), with plastic oil were determined with conventional engine (CE) and SADE with varied injection timing at full load operation of the engine. Injection timing was varied with an electronic sensor. PM was determined by AVL Smoke meter, while NOx , CO and UBHC were measured by Netel Chromatograph multi gas analyzer at full load operation of the engine. Exhaust gas recirculation (EGR) at optimum value of 10% flow rate was provided to control the emissions. The data were compared with neat diesel operation on conventional engine with and without EGR.

Reduction of Pollutants of Insulated Diesel Engine with Plastic Oil with Supercharging

This paper aims at alternative fuel technology for diesel engine and environmental protection. The exhaust emissions from diesel engine are particulate matter (PM), nitrogen oxide (NOx ) levels, carbon mono oxide (CO) emissions and un-burnt hydro carbons (UBHC) and cause severe health hazards when they are inhaled in. They also cause environmental disorders like Global warming, Green-House effect, acid rain etc,. Hence control of these emissions is urgent and an immediate step. Vegetable oils and alcohols are important substitutes for diesel fuel, as they are renewable in nature. Though vegetable oils have comparable properties with diesel fuel, however, they have high viscosity and low volatility causing combustion problems in diesel engines. Alcohols have high volatility but low Cetane number (a measure of combustion quality in diesel engine). Plastic oil derived from waste plastic collected from debris by the process of pyrolysis has equitant calorific value with diesel fuel. However, its viscosity is higher than diesel fuel calls for low heat rejection (LHR) diesel engine. The concept of LHR diesel engine is to minimize the heat flow to the coolant there by increase of thermal efficiency. This LHR engine is useful for burning high viscous and low calorific value fuels. LHR engine consisted of ceramic coated cylinder head engine. The exhaust emissionsof PM, CO, NOx and UBHC with plastic oil were determined with conventional engine (CE) and LHR engine with varied injection timing at full load operation of the engine. Injection timing was varied with an electronic sensor. PM was determined by AVL Smoke meter, while NOx , CO and UBHC were measured by Netel Chromatograph multi gas analyzer at full load operation of the engine. The data was compared with neat diesel operation on conventional engine.

Analysis of the Possibilities of Reduction of Exhaust Emissions from a Farm Tractor by Retrofitting Exhaust Aftertreatment

The paper evaluates particulate matter emissions and exhaust gas components from retrofitted engines of non-road vehicles measured under actual operating conditions. The content is divided into three main parts: formation of guidelines, production of the filter and emission tests. The obtained results clearly indicate excess PM and PN emissions from the engine under actual operating conditions when compared to the limits outlined in the type approval standards. Moreover, it was observed that the actual conditions are reflected to a very small extent at the points included in the stationary homologation test cycle. Based on these observations, the authors decided to modify the stationary test cycle. The measured exhaust gas compositions and their mass flow rates were used to create the geometry of the newly developed filter. The paper contains detailed results of the relative specific exhaust emissions of particulate matter and gaseous components at individual engine operating points. The exhaust emissions analysis made it possible to draw conclusions regarding the operation of the newly designed system. One of them is that fitting a metal-support particulate filter in the exhaust system significantly contributes to reducing the exhaust emissions.

Operational evaluation of atomization indicators for gasoline with admixtures of ethanol and butanol during Keep-Clean tests

The global policy of reducing road transport sector pollution requires the introduction of significantly modified already in use technologies and construction solutions. Currently, direct fuel injection technology is the best solution in terms of reducing fuel consumption and exhaust emissions of standard pollutants into the atmosphere, as well as further improving the engine performance. In terms of exhaust emissions, direct injection spark ignition engines are characterized by significantly higher exhaust emissions of particulate matter (approximately 10 times higher) compared to indirect fuel injection SI engines, they show a greater tendency to knocking combustion and are prone to the formation of harmful deposits on engine parts, including in the fuel injectors. The injector tips located in the combustion chamber are exposed to the direct influence of the very high pressure and temperature caused by the combusting fuel-air mixture, which contributes to the rapid formation of harmful deposits. Operation-based injectors contamination in spark ignition engines results in a reduction of the cross-sectional flow diameter of the injector, which then necessitates the extension of the injection time in order to maintain the fuel dose and the expected engine operating parameters. The tests were carried out on an engine dynamometer and an optical test stand for fuel atomization process. The presented research analyzes indicate the possibility of using admixtures that effectively reduce the likelihood of contamination. The paper presents a results analysis of engine tests performed in accordance with the CEC F-113-KC procedure. Additionally, the injectors were tested to conduct an analysis of the injected fuel stream’s geometric indicators. The range, surface area and speed of the injected fuel stream as well as the fuel distribution in the stream were determined based on an equivalent indicator. The obtained results indicated that ethanol and butanol admixtures of 10% (V/V) to gasoline did not significantly extend the fuel injection time as compared to the reference fuel. A further increase in the proportion of ethanol caused a significant deterioration of the fuel flow and the geometric indicators of the fuel spray.

Comparison of total PM emissions emitted from electric and internal combustion engine vehicles: An experimental analysis

Electric vehicles (EVs) are regarded as zero emission vehicles due to the absence of exhaust emissions. However, they still contribute non-exhaust particulate matter (PM) emissions, generated by brake wear, tire wear, road wear, and resuspended road dust. In fact, because EVs are heavier than internal combustion engine vehicles (ICEVs), their non-exhaust emissions are like to be even higher. While total PM emissions, including exhaust and non-exhaust PM emissions, from ICEVs and EVs have been compared based on the emission factors (EFs) listed in national emission inventories, there have been no comparisons based on experimental determinations.In this study, exhaust and non-exhaust emissions generated from a gasoline ICEV, diesel ICEV, and EV were experimentally investigated. The results showed that the EFs for the total PM emissions of ICEVs and EV were dependent on the inclusion of secondary exhaust PM, the brake pad type, and the regenerative braking intensity of the EV. When only primary exhaust PM emissions were considered in vehicles equipped with non-asbestos organic (NAO) brake pads, the total PM10 EF of the EV (47.7–49.3 mg/V·km) was 10–17 % higher than those of the gasoline ICEV (42.3 mg/V·km) and diesel ICEV (43.2 mg/V·km). However, in vehicles equipped with low-metallic (LM) brake pads, the total PM10 EF of the EV (49.2–57.7 mg/V·km) was comparable or lower than those of the gasoline ICEV (56.3 mg/V·km) and diesel ICEV (57.2 mg/V·km). When secondary PM emissions were included, the EF was always significantly lower for the EV than ICEVs. The total PM10 EF of the EV (47.7–57.7 mg/V·km) was lower than those of the gasoline ICEV (56.5–70.5 mg/V·km) and diesel ICEV (58.0–72.0 mg/V·km). Since secondary PM particles are mostly of submicron size, the EFs of the PM2.5 fraction of the ICEVs (28.7–33.0 mg/V·km) were two times higher than those of the EV (13.9–17.4 mg/V·km).

A Review of Road Traffic-Derived Non-Exhaust Particles: Emissions, Physicochemical Characteristics, Health Risks, and Mitigation Measures.

Implementation of regulatory standards has reduced exhaust emissions of particulate matter from road traffic substantially in the developed world. However, nonexhaust particle emissions arising from the wear of brakes, tires, and the road surface, together with the resuspension of road dust, are unregulated and exceed exhaust emissions in many jurisdictions. While knowledge of the sources of nonexhaust particles is fairly good, source-specific measurements of airborne concentrations are few, and studies of the toxicology and epidemiology do not give a clear picture of the health risk posed. This paper reviews the current state of knowledge, with a strong focus on health-related research, highlighting areas where further research is an essential prerequisite for developing focused policy responses to nonexhaust particles.

Overview of Vehicle Exhaust Particle Number Regulations

Vehicle emissions are a significant source of air pollution in cities. Particulate matter (PM) is a pollutant with adverse health effects. Regulations worldwide determine the PM exhaust emissions of vehicles by gravimetric quantification of the mass deposited on a filter over a test cycle. The introduction of particulate filters as vehicle exhaust gas aftertreatment devices led to low PM emissions. A particle number methodology (counting solid particles > 23 nm), complementary to the PM mass measurement, was developed by the PMP (Particle Measurement Programme) group of the GRPE (Working Party on Pollution and Energy) of the UNECE (United Nations Economic Commission for Europe) during the first decade of the 21st century. The methodology was then introduced in the EU (European Union) regulations for light-duty (2011), heavy-duty (2013), and non-road mobile machinery (2019). In parallel, during the last 15 years, UN (United Nations) regulations and GTRs (Global Technical Regulations) including this methodology were also developed. To address the on-road emissions, the EU introduced RDE (real-driving emissions) testing with PEMS (portable emissions measurement systems) in 2017. Other countries (e.g., China, India) have also started adopting the number methodology. The PMP group recently improved the current laboratory and on-board methodologies and also extended them to a lower particle size (counting solid particles > 10 nm). Due to the rapid evolution of the vehicle exhaust particle number regulations and the lack of a summary in the literature, this paper gives an overview of current and near future regulations. Emphasis is given on the technical specifications and the changes that have taken place over the years.

Potential release of nano-carbon black from tire-wear particles through the weathering effect

Carbon black (CB) is commercially produced by the partial combustion of hydrocarbons, mainly used as a reinforcing material in tires. Generally, driving cars emit a considerable amount of particulate matter (PM), and this acts as a major source of PM in urban areas. While exhaust PM emissions are strictly regulated and controlled by the government, non-exhaust PM emissions from tire-wear and break-wear have been overlooked. Additionally, as CB is tightly bound in the rubber matrix of tire-wear particles (TWP), the possibility of nanoparticle exposure from TWP has also been ruled out. However, TWP could be fragmented through the weathering effect, continuous abrasion on the road, and resuspension. Therefore, in this study, we investigated the potential release of nano-CB from TWP through the weathering effect using a ball milling process. With increasing milling time, countless free-bound nanoparticles were detached from the parent TWP samples. Based on several analyses of elemental composition, morphological change, and crystallinity, it is possible to define the free-bound nanoparticles as nano-CB. Additionally, nanosized carbon-based materials were found in real-time field tests on highways. Therefore, it has been confirmed that nanosized carbon particles can be released from TWP or exhaust PM.

An experimental-computational study of DPF soot capture and heat regeneration

ABSTRACTA diesel particulate filter (DPF) can effectively reduce the exhaust emissions of particulate matter (PM) and meet emission regulations. We report herein an experimental-numerical study to investigate the soot capture and regeneration behavior in a commonly used DPF. Simulations are performed using the AVL FIRE software that considers a fairly detailed DPF model. The model is validated using measured pressure drop history during soot capture, and temperature history during regeneration from a parallel experimental study using a diesel engine equipped with a DPF. Then, a detailed numerical study is performed to examine the soot capture and heat regeneration processes, and characterize the effects of various parameters on these processes and on DPF performance. Results indicate that the pressure drop during soot loading can be reduced by increasing the CPSI (channels per square inch), minimizing the amount of residual soot in each regeneration cycle, and using moderate gas flow rates. The DPF regeneration performance is characterized in terms of the rates of temperature rise and soot oxidation. Results indicate that these rates are enhanced, as the oxygen content in the exhaust stream is increased to about 12%, the rate of thermal heating is moderately increased, and as the exhaust gas flow rate is increased. Thus, the regeneration efficiency can be significantly improving by optimizing these parameters.

The genotoxicity of organic extracts from particulate truck emissions produced at various engine operating modes using diesel or biodiesel (B100) fuel: A pilot study

An analysis of the toxic effects of emissions should reflect real traffic conditions. The exhaust emissions of particulate matter from diesel engines strongly depend on their operating conditions, with low-speed, low-load "urban creep" conditions, common for truck traffic in heavily congested urban areas, being one of the worst. We aimed to detect the genotoxicity of organic extracts from particulate matter in the exhaust of the diesel engine Zetor 1505 running on diesel and biodiesel (B100) fuels at characteristic modes of extended "urban creep", typical for transit truck traffic in Prague, comparing the first 5 min of idling with extended (20–80 min) idling, full load after idle, "stabilized" full load, and 30% load. The diluted exhaust was sampled with high volume samplers on glass fiber fluorocarbon coated filters. The filters were extracted with dichloromethane and DNA damage was analyzed in A549 cells using comet assay, with the inclusion of formamidopyrimidine DNA glycosylase (FPG) and endonuclease III (ENDOIII) to recognize oxidized DNA bases. The cells were exposed to extractable organic matter (EOM) for 4 and 24 h at non-cytotoxic dose corresponding to 0.001 m3 of undiluted exhaust gas per ml cell media. At the 4 h exposure interval, all samples from B100 and diesel emissions induced DNA damage. EOM from the extended idle engine mode exerted the strongest genotoxic effect for both fuels. Twenty hours later, the cells exposed to diesel EOM exhibited a further increase of DNA strand breaks compared to the preceding interval. In contrast, DNA damage seemed to be fully repaired in cells treated with EOM derived from biodiesel B100. The preliminary results suggest that (i) diesel emissions are more genotoxic than the emissions from B100, (ii) biodiesel induced DNA lesions are repaired within 24 h.

Exhaust emissions of particulate matter from light-duty vehicles – an overview and the current situation

Emissions of particulate matter associated with the use of light-duty vehicles are an increasingly important topic, with more and more political attention focused on this issue. Now that direct injection Diesel engines feature DPFs, particle emissions from other engine types operating on other fuels are also of great interest. This paper discusses the phenomenon in general, briefly reviews worldwide legislation and emissions limits and presents the results of a laboratory test programme measuring the particle emissions from a range of vehicles. The experimental programme showed that the engine/fuel type has a greater impact on particle emissions than the test conditions.

Impact of aggressive drive cycles on motor vehicle exhaust PM emissions

Aggressive drive cycles can cause substantial discrepancies between particulate matter (PM) measurement methods and increased emissions variability. Previous work demonstrated good agreement, within ~10%, between aerosol instruments and gravimetric determinations of PM mass emissions from gasoline direct injection engine (GDI) vehicles run over the Federal Test Procedure (FTP). In contrast, the present study reveals discrepancies of a factor of three or more for these vehicles run over the US06 portion of the supplemental FTP test. Two aspects of this are examined: 1) Changes in particle composition and morphology and 2) variability associated with vehicle history and test preparation. PM emissions during the US06 cycle are often accompanied by a strong nucleation mode. The organic to elemental carbon ratio increases relative to the FTP cycle. Also, the black carbon to elemental carbon ratio decreases, suggesting the formation of brown soot. The origins of these changes are not entirely clear, but are likely associated with the high engine exhaust temperatures during the US06 cycle. This also contributes to the higher test to test variability observed for the US06 versus FTP cycle. High temperatures can thermally desorb and pyrolyze various materials, including heavy hydrocarbons, ash, and inorganic salts deposited in the exhaust pipe, catalytic converter, and muffler that provide an additional PM source not present during FTP driving. The first day’s PM mass emissions are often substantially higher than on following days for the US06 cycle, but not the FTP. There is also a distinct drop in PM emissions between first and subsequent US06 cycles run in series.

Reactive Oxidative Species and Speciated Particulate Light-Duty Engine Emissions from Diesel and Biodiesel Fuel Blends

It is well established that particulate matter (PM) continues to be a major air pollutant challenge for human health globally, and vehicle exhaust PM emissions have been linked to many adverse health effects. However, the relative toxicity of biodiesel emissions compared to petroleum diesel remains unclear. Given the legislated mandates to increase biodiesel fuel use in response to energy security and climate concerns, in this study we examined the relationships between biodiesel fuel blend, exhaust particle oxidative potential (OP), and PM composition. Mechanistically, there is a growing consensus that the formation of reactive oxygen species (ROS) due to PM exposure leads to subsequent oxidative stress and inflammation at the cellular level. Here, dithiothreitol (DTT) assays were performed on impinger samples of PM obtained from light-duty diesel engine transient cycle emission tests with two biodiesel feedstocks, soybean (SOY) and waste vegetable oil (WVO), blended with ultralow sulfur petrodiesel at f...

Efficacy of Recent Emissions Controls on Road Vehicles in Europe and Implications for Public Health

Road traffic is a major source of urban air pollution responsible for substantial premature mortality. Until recently, attention has focussed primarily on exhaust emissions of particulate matter from traffic as a causal factor. From analysis of air quality measurement data from the UK and France, we demonstrate that road traffic exhaust has a far greater impact on concentrations of nitrogen dioxide than of PM2.5. PM2.5 and carbonaceous particle concentrations have been declining appreciably since 2010/11 due to the use of diesel particle filters, but little change is seen in nitrogen dioxide over the period from 1995 to 2015. It is shown that the effect of NO2 from road traffic upon premature mortality was ten-fold greater than that of PM2.5 even before the widespread use of diesel particle filters, and is now considerably larger. The overwhelming contribution of diesel compared to gasoline-fuelled vehicles to emissions of both PM2.5 and NO2 emphasises the importance of further controls on emissions from diesels.

Application of the dual Pegasor Particle Sensor to real-time measurement of motor vehicle exhaust PM

In this study we explore the performance of a recently introduced exhaust particle detection concept, the dual PPS (dPPS), to simultaneously measure motor vehicle exhaust particle size, number, and mass in real-time. To this end, the dPPS was evaluated in two laboratories in measuring diesel and gasoline direct injection (GDI) exhaust particulate matter (PM) over the US and EU type approval cycles against instruments regularly used for PM emissions measurements. The analysis included inter-correlation testing to validate responses of different PPS units in a dPPS configuration, as well as determination of the optimal operation parameters to minimize data inversion errors. The experimental results demonstrate that dPPS is capable of providing real-time information on exhaust PM emissions, and that its measurement is in close agreement with reference instruments. Given its compact dimensions and raw exhaust sampling capacity, dPPS is an appropriate candidate as a portable emissions measurement system (PEMS) to measure both particle mass and number exhaust emissions. The concept and the associated operation algorithm allow to change the lowest particle size detection threshold, thus making the technique suitable to 23nm, which is the current threshold in EU regulations, or a lower one if so desired.

Regulated and unregulated emissions from modern 2010 emissions-compliant heavy-duty on-highway diesel engines

The U.S. Environmental Protection Agency (EPA) established strict regulations for highway diesel engine exhaust emissions of particulate matter (PM) and nitrogen oxides (NOx) to aid in meeting the National Ambient Air Quality Standards. The emission standards were phased in with stringent standards for 2007 model year (MY) heavy-duty engines (HDEs), and even more stringent NOX standards for 2010 and later model years. The Health Effects Institute, in cooperation with the Coordinating Research Council, funded by government and the private sector, designed and conducted a research program, the Advanced Collaborative Emission Study (ACES), with multiple objectives, including detailed characterization of the emissions from both 2007- and 2010-compliant engines. The results from emission testing of 2007-compliant engines have already been reported in a previous publication. This paper reports the emissions testing results for three heavy-duty 2010-compliant engines intended for on-highway use. These engines were equipped with an exhaust diesel oxidation catalyst (DOC), high-efficiency catalyzed diesel particle filter (DPF), urea-based selective catalytic reduction catalyst (SCR), and ammonia slip catalyst (AMOX), and were fueled with ultra-low-sulfur diesel fuel (~6.5 ppm sulfur). Average regulated and unregulated emissions of more than 780 chemical species were characterized in engine exhaust under transient engine operation using the Federal Test Procedure cycle and a 16-hr duty cycle representing a wide dynamic range of real-world engine operation. The 2010 engines’ regulated emissions of PM, NOX, nonmethane hydrocarbons, and carbon monoxide were all well below the EPA 2010 emission standards. Moreover, the unregulated emissions of polycyclic aromatic hydrocarbons (PAHs), nitroPAHs, hopanes and steranes, alcohols and organic acids, alkanes, carbonyls, dioxins and furans, inorganic ions, metals and elements, elemental carbon, and particle number were substantially (90 to >99%) lower than pre-2007-technology engine emissions, and also substantially (46 to >99%) lower than the 2007-technology engine emissions characterized in the previous study.Implications: Heavy-duty on-highway diesel engines equipped with DOC/DPF/SCR/AMOX and fueled with ultra-low-sulfur diesel fuel produced lower emissions than the stringent 2010 emission standards established by the U.S. Environmental Protection Agency. They also resulted in significant reductions in a wide range of unregulated toxic emission compounds relative to older technology engines. The increased use of newer technology (2010+) diesel engines in the on-highway sector and the adaptation of such technology by other sectors such as nonroad, displacing older, higher emissions engines, will have a positive impact on ambient levels of PM, NOx, and volatile organic compounds, in addition to many other toxic compounds.

Effects of fuels, engine load and exhaust after-treatment on diesel engine SVOC emissions and development of SVOC profiles for receptor modeling

Diesel exhaust emissions contain numerous semivolatile organic compounds (SVOCs) for which emission information is limited, especially for idling conditions, new fuels and the new after-treatment systems. This study investigates exhaust emissions of particulate matter (PM), polycyclic aromatic hydrocarbons (PAHs), nitro-PAHs (NPAHs), and sterane and hopane petroleum biomarkers from a heavy-duty (6.4 L) diesel engine at various loads (idle, 600 and 900 kPa BMEP), with three types of fuel (ultra-low sulfur diesel or ULSD, Swedish low aromatic diesel, and neat soybean biodiesel), and with and without a diesel oxidation catalyst (DOC) and diesel particulate filter (DPF). Swedish diesel and biodiesel reduced emissions of PM2.5, Σ15PAHs, Σ11NPAHs, Σ5Hopanes and Σ6Steranes, and biodiesel resulted in the larger reductions. However, idling emissions increased for benzo[k]fluoranthene (Swedish diesel), 5-nitroacenaphthene (biodiesel) and PM2.5 (biodiesel), a significant result given the attention to exposures from idling vehicles and the toxicity of high-molecular-weight PAHs and NPAHs. The DOC + DPF combination reduced PM2.5 and SVOC emissions during DPF loading (>99% reduction) and DPF regeneration (83–99%). The toxicity of diesel exhaust, in terms of the estimated carcinogenic risk, was greatly reduced using Swedish diesel, biodiesel fuels and the DOC + DPF. PAH profiles showed high abundances of three and four ring compounds as well as naphthalene; NPAH profiles were dominated by nitronaphthalenes, 1-nitropyrene and 9-nitroanthracene. Both the emission rate and the composition of diesel exhaust depended strongly on fuel type, engine load and after-treatment system. The emissions data and chemical profiles presented are relevant to the development of emission inventories and exposure and risk assessments.