Emissions of polycyclic aromatic hydrocarbons (PAHs) and nitro-PAHs from heavy-duty diesel vehicles with DPF and SCR

Indoor air levels of polycyclic aromatic compounds (PAC) in public buildings with creosote impregnated constructions - A pilot case study using passive samplers

Creosote has been used in Sweden as a wood preservative in buildings since the 19th century. These buildings can function as workplaces, homes, and cultural buildings to which the public has access. Creosote contains polycyclic aromatic hydrocarbons (PAH) which are well known carcinogens. To understand exposure and risks in an indoor environment, it is important to determine air levels of parent PAHs as well as the more toxic nitrated and oxygenated PAH derivatives (NPAH, OPAH). This study aims to investigate indoor air levels of polycyclic aromatic compounds (PACs) e.g., PAH, NPAH, OPAH and dibenzothiophenes in buildings containing creosote sources and whether these levels pose a health risk. Four cultural buildings were studied, all located within a radius of 130 m. Two were known to have creosote sources, and two had not. Polyurethane foam passive air samplers (PUF-PAS) were used to indicate possible point sources. PUF-PAS measurements were performed for one month in each building winter and summer. Simultaneously, PAC outdoor level measurements were performed. Buildings with creosote impregnated constructions had notably higher indoor air levels of PAC (31-1200 ng m-3) compared to the two buildings without creosote sources (14-45 ng m-3). The PAH cancer potency (sum of benzo[a]pyrene equivalents (BaPeq)) was more than one order of magnitude higher in the buildings containing creosote impregnated wood compared to reference buildings. The highest value was 5.1 BaPeq ng m-3 which was significantly higher than the outdoor winter measurement (1.3 BaPeq ng m-3). Fluoranthene and phenanthrene, with significant distribution in gas phase, but also several particulate NPAHs contributed significantly to the total cancer risk. Thus, creosote containing buildings can still contaminate the indoor air with PACs despite being over a hundred years old. The PUF-PAS was shown to be a good tool providing quantitative/semiquantitative measures of PACs exposure in indoor microenvironments.

Determination of carbonyls and size-segregated polycyclic aromatic hydrocarbons, and their nitro and alkyl analogs in emissions from diesel-biodiesel-ethanol blends

This study characterizes carbonyls (RCHO), polycyclic aromatic hydrocarbons (PAHs), their nitrated (nitro-PAHs) and alkylated (alkyl-PAHs) in particulate matter in the exhaust emissions of a diesel engine. The measurements were made with a standard engine, often found in vans used in Brazil, fueled with pure commercial diesel and mixtures of 10, 20, and 30% biodiesel with 2, 4, and 6% of ethanol. Particulate matter sampling was carried out with a 10-stage cascade impactor. Chemical analyses for PAHs and their derivatives were conducted using gas phase chromatography-mass spectrometry (GC/MS). RCHO were sampled using impingers with 2,4-DNPH and analyzed using HPLC with UV detection. The results showed that emissions of all the PAHs and their derivatives were reduced with the use of biodiesel and ethanol, with the exception of the blend of 30% biodiesel with 4% ethanol. However, all the RCHO emissions increased with biodiesel and ethanol. High correlations were observed between the emissions of PAHs, alkyl-PAHs and nitro-PAHs, which suggests a similarity in the formation mechanisms of these compounds. All PAHs' emissions have a strong negative correlation with biodiesel content and with RCHO emissions and a medium correlation with ethanol content. In contrast, biodiesel and ethanol with the RCHO emissions lead to a positive correlation coefficient of these compounds which is more pronounced for biodiesel than ethanol.

Sub-toxic events induced by truck speed-facilitated PM2.5 and its counteraction by epigallocatechin-3-gallate in A549 human lung cells

To distinguish the influences of fuel type and truck speed on chemical composition and sub-toxic effects of particulates (PM2.5) from engine emissions, biomarkers-interleukin-6 (IL-6), cytochrome P450 (CYP) 1A1, heme oxygenase (HO)-1, and NADPH-quinone oxidoreductase (NQO)-1-were studied in A549 human lung cells. Fuel type and truck speed preferentially affected the quantity and ion/polycyclic aromatic hydrocarbon (PAH) composition of PM2.5, respectively. Under idling operation, phenanthrene was the most abundant PAH. At high speed, more than 50% of the PAHs had high molecular weight (HMW), of which benzo[a]pyrene (B[a]P), benzo[ghi]perylene (B[ghi]P), and indeno[1,2,3-cd]pyrene (I[cd]P) were the main PAHs. B[a]P, B[ghi]P, and I[cd]P caused potent induction of IL-6, CYP1A1, and NQO-1, whereas phenanthrene mildly induced CYP1A1. Based on the PAH-mediated induction, the predicted increases in biomarkers were positively correlated with the measured increases. HMW-PAHs contribute to the biomarker induction by PM2.5, at high speed, which was reduced by co-exposure to epigallocatechin-3-gallate.

Comprehensive characterization of polycyclic aromatic hydrocarbon emissions from heavy-duty diesel vehicles utilizing GC × GC-ToF-MS

Comprehensive characterization of diesel vehicle emitted polycyclic aromatic hydrocarbon (PAH) emissions is yet to achieve due to the limitation of analytical methods. Therefore, we herein developed a two-dimensional gas chromatography time-of-flight mass spectrometry (GC × GC-ToF-MS) method and quantified the total PAHs from diesel vehicles based on their characteristic fragments and mass spectral patterns. Overall, the emission factors (EFs) of total PAHs (gas + particle) are observed to range from 4.1 ± 2.5 mg km^-1 to 51.4 ± 22.2 mg km^-1 under cold-start and hot-start conditions for one China IV and two China VI heavy-duty diesel vehicles (HDDVs), of which the un-speciated PAHs account for more than 97%. Gaseous PAHs (g-PAHs) are dominated by three-ring PAHs, whereas particulate PAHs (p-PAHs) are dominated by two-ring PAHs. The total PAHs partition significantly into the gas phase for whole fleets and cycles, except that five-ring PAHs partition almost completely into the particle phase. The aftertreatment technologies (e.g., diesel particulate filter, DPF) significantly reduce the total PAH emissions by 49.8 ± 33.2%. The minimum toxic equivalency factors (TEFs) are deployed to estimate the toxicity of the total PAHs. Much higher toxicity is obtained than those in previous studies, indicating that the PAH toxicity of diesel vehicle emissions might be largely underestimated.

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.

Use of hydrous ABE-glycerin-diesel microemulsions in a nonroad diesel engine - Performance and unignorable emissions

Oversupply, extra energy consumption, and CO₂ emissions from the refinery of biodiesel-derived glycerin (G) led to the consideration of its use as an alternative fuel. In this study, a nonroad diesel engine generator was employed to represent potential emissions under stringent regulated standards. G-diesel has been reported to reduce nitrogen oxides (NOx) and soot levels but increase CO and hydrocarbon emissions. A bio-producible acetone-butanol-ethanol (ABE) solution with multiple polarities was added to stabilize the glycerin and water in diesel examined in this study. A series of ABE-G-diesel blends were prepared to form the thermostable microemulsions. Four blends with small and well-dispersed bubbles were tested in the engine generator. The specific thermal efficiencies of the engine were slightly improved by using ABE-G from regular diesel due to better spray quality, longer ignition delay, and fuel-oxygen content that would enhance combustion. Meanwhile, the PM-NOx-CO emission trade-off in the previous study has been overcome by using ABE-G-diesel since the better fuel atomization and more premixed combustion were approached, as well as the lower and homogeneous in-cylinder temperature caused by water content and micro-explosion. However, the condensable particulate matter and nitro-PAHs were also observed and realized their unignorable contribution, which has not been regulated and even researched for the generators. Fortunately, the new fuels could inhibit both of them to a certain degree. Consequently, this study proposes using recyclable glycerin with a simple pretreatment mixed with ABE and diesel for greener nonroad diesel engine especially those equipped with low-grade aftertreatment.

FT-ICR mass spectrometry for molecular characterization of water-insoluble organic compounds in winter atmospheric fine particulate matters

Water-insoluble organic compounds (WIOCs) are an important fraction of atmospheric fine particulate matters (PM_2.5), which could affect the climate system and threaten human health potentially. In this study, molecular characterization of WIOCs in PM_2.5 were investigated by 15 T Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) with atmospheric pressure photoionization (APPI) source in positive ion mode. A total of 2573 and 1875 molecular formulas were identified in WIOCs extracted by dichloromethane, which were collected in hazy and normal days, respectively. The identified molecular formulas were further classified into four major subgroups, including CH, CHN, CHO and CHNO compounds. CHO compounds predominated in WIOCs, accounting for more than 60% in both samples. CHNO compounds (26.6%) and CH compounds (16.1%) were the second highest subgroups in WIOCs from the hazy days and normal days, respectively. The relative abundance and number of nitro-substituted aromatic compounds were significantly higher in hazy days than in normal days. The molecular composition of WIOCs was more complex in hazy days while more aromatic compounds were identified in normal days.

Intermediate volatile organic compounds emissions from vehicles under real world conditions

Real-world vehicle emission factors (EFs) for the total intermediate volatile organic compounds (total-IVOCs) and volatile organic compounds (VOCs) from mixed fleets of vehicles were quantified in the Yangtze tunnel in Shanghai. Relationships of EFs of IVOCs with fleet compositions and vehicle speed as well as secondary organic formation potentials (SOAFPs) from IVOCs and VOCs were studied. Multiple linear regression (MLR) was used to estimate EFs of total-IVOCs for gasoline and diesel vehicles. IVOCs were classified into unresolved complex mixtures (unspeciated cyclic compounds and branched alkanes (b-alkanes)) and speciated targets (11 n-alkanes and ten polycyclic aromatic hydrocarbons (PAHs)). The results showed that the average EF of total-IVOCs was 24.9 ± 7.8 mg/(km·veh), which was comparable to that of VOCs. Unspeciated cyclic compounds and b-alkanes dominated the main composition (~77% and ~19%), followed by n-alkanes (~4%) and PAHs (~1%). EFs of IVOCs showed a significant, positive relationship with diesel vehicle fractions (p < 0.05). EFs of IVOCs dropped notably with the decrease of the diesel vehicle fractions. SOAFP produced by the total organic compounds (IVOCs + VOCs) was 8.9 ± 2.5 mg/(km·veh), in which up to 86% of SOAFP was from IVOCs. Estimated EFs of total-IVOCs for gasoline vehicles and diesel vehicles were 15.3 and 219.8 mg/(km·veh) respectively. Our results demonstrate that IVOCs emitted from diesel vehicles are the main emission sources under real world conditions and significant contributions of IVOCs emissions to SOA formation is evident, which indicates the necessity of making control policies to reduce IVOCs emissions from vehicles.

Urinary Amino-Polycyclic Aromatic Hydrocarbons in Urban Residents: Finding a Biomarker for Residential Exposure to Diesel Traffic

Despite substantial evidence of marked exposure to and ill-health effects from diesel exhaust (DE) emissions among occupational population (e.g., miners, truck drivers, and taxi drivers), it is less understood to what extent non-occupational population was exposed to DE among various combustion sources, largely due to the lack of biomarkers that would indicate specific exposure to DE. We evaluated whether urinary amino-polycyclic aromatic hydrocarbons (APAHs), such as major metabolites of DE-specific nitrated PAHs, can be used as DE exposure biomarkers in residential settings. We measured five urinary APAHs in 177 urine samples from 98 UK residents, 89 (91%) of them were London residents, and estimated their residential proximity to various traffic indicators (e.g., the road type, road length, traffic flow, and traffic volume). Participants living within 100 m of major roads exhibited increased levels of all five APAHs, among which 2-amino-fluorene (2-AFLU) reached statistical significance (p < 0.05). We estimated that a 10 m increase in the length of nearby major roads (<100 m) was associated with a 4.4% (95% CI of 1.1 to 7.6%) increase in 2-AFLU levels. Levels of 2-AFLU were significantly associated with the traffic flow of nearby buses and heavy-duty vehicles but not motorbikes, taxis, or coaches. We did not observe a significant association between distance to major roads or the sum of the major road length within 100 m with the other four biomarker concentrations. These results suggest the use of urinary 2-AFLU as a biomarker of DE exposure in urban residents.

Chemical and toxicological characterization of particulate emissions from diesel vehicles

This paper presents a detailed chemical and toxicological characterization of the diesel particulate matter (PM) emitted from diesel vehicles running on a chassis dynamometer under different driving conditions. Chemical analyses were performed to characterize the contents of organic carbon (OC), elemental carbon (EC), and 31 polycyclic aromatic hydrocarbons (PAHs) in the collected PM samples. The OC-EC analysis results revealed that PM emissions from diesel vehicles in this study were dominated by OC and that the emission of vehicles equipped with diesel particulate filters had high OC/EC ratios. The PAH analysis results revealed that 4- and 5-ring PAHs were the dominant PAHs in the OC fraction of the PM samples. Particle toxicity was evaluated through three toxicological markers in human A549 cells, namely (1) acellular 2,7-dichlorofluorescein (DCFH) for oxidative potential, (2) interleukin-6 (IL-6) for inflammation, and (3) glutathione (GSH) for antioxidation after exposure. Statistical analyses revealed that vehicle sizes have statistically significant effects on the concentrations of the markers. Correlation analysis between PAHs and toxicological markers revealed that significant correlations existed between specific compounds and markers. Our results can be used as a reference by policy makers to formulate emission control strategies and as a dataset for other modeling studies.

Effect of operating conditions on the chemical composition, morphology, and nano-structure of particulate emissions in a light hydrocarbon premixed charge compression ignition (PCCI) engine

The aim of present work is to bridge the gap of knowledge concerning crystallite size, graphene layers curvature and inter-layer distance as nanostructure characteristics of soot primary particles, and also to comprehensively characterize the morphology of soot emission in a light hydrocarbon premixed charge compression ignition (PCCI) engine. In this study, the chemical composition, morphology and nano-structure of particulate emissions between conventional diesel and light hydrocarbon PCCI engine were performed with thermogravimetric analysis, gas chromatography mass spectrometry, and high-resolution transmission electron microscopy technology. The results show that the volatile matter content of light hydrocarbon is much higher than that of diesel, and thermogravimetry and differential thermogravimetry curves of light hydrocarbon shift to low temperature regions. The total organic components of particulate matter of light hydrocarbon PCCI engine are less, and the corresponding separation time is shorter. The structure of particles produced in light hydrocarbon PCCI engine is more open, and the size of aggregates is smaller. Fractal dimensions of 1.774 and 1.691 are obtained for soot particles in light hydrocarbon PCCI engine, compared to that of 1.81 and 1.785 in conventional diesel engine. Compared to conventional diesel engine, fringe separation distance and fringe tortuosity in light hydrocarbon PCCI engine are smaller while fringe length is larger. The primary particle nanostructures of light hydrocarbon PCCI engine incline to graphitize and change into the orderly structure. Compared with conventional diesel combustion, the average primary particle diameter of light hydrocarbon PCCI approximately reduces 2.0% at 75% load and 18.2% at 100% load, respectively.

Measurement of urinary 1-aminopyrene and 1-hydroxypyrene as biomarkers of exposure to diesel particulate matter in gold miners

Metabolites of polycyclic aromatic hydrocarbons measured in human samples are often used as biomarkers of exposure to diesel engine exhaust (DEE). The aim of this study was to assess the changes in urinary levels of 1-aminopyrene (1-AP) and 1-hydroxypyrene (1-OHP) and their relationship with Elemental Carbon (EC), as a component of diesel engine exhaust exposure, among a hard-rock gold-mining population. Urine samples were collected at the beginning and end of a 12-hour work shift from 100 underground and above ground gold miners. Miners were fitted with personal exposure monitoring equipment to quantify exposure to DEE, measured as Elemental Carbon (EC), across their 12-hour work shift. General linear regression assessed associations of the post-shift urinary 1-AP and 1-OHP concentrations with EC, controlling for age, gender, the pre-shift biomarker level, Body Mass Index (BMI), days on current shift, time in mining, smoking status and second-hand smoke exposure. The concentrations of 1-AP and 1-OHP increased significantly across a 12-hour mining work shift. Moreover, consistent with the sensitivity analysis, the concentration of 1-AP was significantly associated with EC after adjustments. Urinary 1-OHP, but not 1-AP was significantly associated with current smoking. Urinary 1-AP may be a more robust and specific biomarker of DEE than 1-OHP.

Characterization of PM2.5-bound polycyclic aromatic hydrocarbons and their derivatives (nitro-and oxy-PAHs) emissions from two ship engines under different operating conditions

Emissions from ship exhaust have been recognized as an important source of air pollution in coastal areas. To investigate the impacts of engine type, fuel and operating conditions on polycyclic aromatic compounds (PACs) emissions, particle matter (PM_2.5) samples emitted from an inland-river bulk freighter (BF) using marine diesel oil (MDO) and an ocean-going passenger vessel (PV) using heavy fuel oil (HFO) were collected under five operation conditions (preheating, leaving, cruising, entering and berthing). The concentrations of 17 polycyclic aromatic hydrocarbons (PAHs), 12 nitro-PAHs (NPAHs) and 4 oxygenated-PAHs species were determined. The concentrations of ΣPAHs, ΣNPAHs and ΣOPAHs measured on the BF and PV exhausts ranged from 1.95 to 417 μg/m³, 86.5 to 6.89 × 10³ ng/m³ and 2.00-102 μg/m³, respectively. Both ships showed a high proportion of four-ring PAHs, while the BF had more three-ring PAHs (34.00-70.38%) and the PV had more five-ring PAHs (30.02-35.95%). The calculation of indicatory PACs are able to increase the precision of source appointment. The emission factors (EFs) of PACs under maneuvering (including preheating, leaving, entering and berthing) was much higher than those under cruising, which might be due to the engine load, fuel consumption, and secondary reactions. Compared with HFO, combustion with MDO decreased the power-based ΣPAH EFs by 82-99%, power-based ΣNPAH EFs by 86-98%, and power-based ΣOPAHs EFs by 50-82%. These data highlight the importance of quantifying and monitoring ship emissions in close proximity to port area, and are useful for enhancing the relevant databases and improving the accuracy of ship emission inventories.

Evaluation of 1-Nitropyrene as a Surrogate Measure for Diesel Exhaust

We investigated the viability of particle bound 1-nitropyrene (1-NP) air concentration measurements as a surrogate of diesel exhaust (DE) exposure, as compared with industry-standard elemental carbon (EC) and total carbon (TC) measurements. Personal exposures are reported for 18 employees at a large underground metal mine during four different monitoring campaigns. Full-shift personal air exposure sampling was conducted using a Mine Safety and Health Administration (MSHA) compliant diesel particulate matter (DPM) impactor cassette downstream of a GS-1 cyclone pre-selector. Each DPM filter element was analyzed for EC and organic carbon (OC) using NIOSH Method 5040. After EC and OC analysis, the remaining portion of each DPM filter was analyzed for 1-NP using liquid chromatography tandem mass spectrometry (LC/MS/MS). We observed high correlations between the quantiles of 1-NP and EC exposures across 10 different work shift task groups (r = 0.87 to 0.96), and a linear relationship with a slope between 6.0 to 6.9 pg 1-NP per µg EC. However, correlation between 1-NP and EC was weak (r =0.34) for the 91 individual sample pairs due to low EC concentrations and possible heterogeneity of DE composition. While both 1-NP and EC differentiated between high and low exposure groups categorized by job location, measurements of 1-NP, but not EC further differentiated between specific job activities. Repeated measurements on individual subjects verified the relationship between 1-NP and EC and demonstrated substantial within-subject variability in exposure. The detection limit of TC air concentration ranged between 18 and 28 µg m-3 and was limited by OC contamination of the quartz filters in the MSHA compliant DPM samplers.

Characterization and quantification of PM2.5 emissions and PAHs concentration in PM2.5 from the exhausts of diesel vehicles with various accumulated mileages

Road traffic is one of the main sources of particulate matter in the atmospheric environment. Notwithstanding its significance, there are noteworthy challenges in quantitative assessment of its contribution to the concentrations of airborne. This study reports on the characterization and quantification of PM_2.5 emissions and PAHs concentration in PM_2.5 from the exhausts of on-road diesel vehicles with various accumulated mileages in Kaohsiung City, Taiwan. Urban areas could be a subject matter not just in connection to deprived air quality, but similarly to pollution of other significant environmental media by air contaminants. To that end, our study intends to estimate the PM_2.5 emissions from diesel vehicles using diesel fuels and to analyze the PM_2.5 emissions and PAHs concentration in PM_2.5. In this study, particulate matters (PM_2.5) were characterized and quantified from a place impacted by diesel vehicles fueled with diesel in Kaohsiung City, Taiwan. The tested diesel vehicles with various accumulated mileages overs the model year comprising of the vehicles registered from 1984 to 2012 from different manufacturers (or brands) ranging from 8733 to 965,026 km (average 445,433 km) accumulative mileages. Exhaust constituents include CO, NOx, PM_2.5 and particle phase PAHs. The concentrations of twenty-one (21) priority polycyclic aromatic hydrocarbons (PAHs) were studied in the samples by their relationship with atmospheric PM_2.5. However, in relations to cumulative mileages, lower cumulative mileage (mileage <20,000 km) has the lowest CO and NOx emission factors. The mileage ranged from 20,001 to 30,000 km had an increased CO and NOx emission factors, respectively. Interestingly, with the increased high number of mileages ranged from 30,001 to 50,000 km, CO and NOx emission factor was observed to be declining, respectively. This could be attributed to the technological changes on new diesel vehicle models. But nonetheless, the trend of CO emission factor was found to be higher with an increasing of cumulative mileages as compared to the mileage that reached lower than 30,000 km.

Characterization and carcinogenic risk assessment of polycyclic aromatic and nitro-polycyclic aromatic hydrocarbons in exhaust emission from gasoline passenger cars using on-road measurements in Beijing, China

The polycyclic aromatic hydrocarbon (PAH) and nitro-polycyclic aromatic hydrocarbon (NPAH) emissions from 16 gasoline passenger cars, encompassing five emission standards and two driving conditions, were tested using a portable emission measurement system (PEMS) in Beijing under on-road conditions. In total, 16 PAHs and 9 NPAHs were quantified in both the gaseous and particulate phases by high-performance liquid chromatography (HPLC). The results indicated that lower PAH and NPAH emissions were observed with improved emission standards, especially for China 3 to China 5 vehicles (P < 0.05). Higher emission factors (EFs) were detected on nonhighway roads than on highway roads due to incomplete combustion. Although most PAHs and NPAHs were in the gas-phase, the TEQ_BaP of the particulate-phase PAHs was 4.2 times higher than that of the gas-phase PAHs, whereas the opposite pattern was observed for NPAHs. The TEQ_BaP EFs on nonhighway roads were 1.0-2.3 times higher than those on highway roads. The results of this study will be valuable for estimating the emissions and performing carcinogenic risk assessment of PAHs and NPAHs from urban gasoline passenger cars on roads. Formulating more stringent regulations and emission control technologies for PAHs and NPAHs is important.

Polycyclic Aromatic Hydrocarbons (PAHs) and nitrated analogs associated to particulate matter emission from a Euro V-SCR engine fuelled with diesel/biodiesel blends

Among the new technologies developed for the heavy-duty fleet, the use of Selective Catalytic Reduction (SCR) aftertreatment system in standard Diesel engines associated with biodiesel/diesel mixtures is an alternative in use to control the legislated pollutants emission. Nevertheless, there is an absence of knowledge about the synergic behaviour of these devices and biodiesel blends regarding the emissions of unregulated substances as the Polycyclic Aromatic Hydrocarbons (PAHs) and Nitro-PAHs, both recognized for their carcinogenic and mutagenic effects on humans. Therefore, the goal of this study is the quantification of PAHs and Nitro-PAHs present to total particulate matter (PM) emitted from the Euro V engine fuelled with ultra-low sulphur diesel and soybean biodiesel in different percentages, B5 and B20. PM sampling was performed using a Euro V - SCR engine operating in European Stationary Cycle (ESC). The PAHs and Nitro-PAHs were extracted from PM using an Accelerated Solvent Extractor and quantified by GC-MS. The results indicated that the use of SCR and the largest fraction of biodiesel studied may suppress the emission of total PAHs. The Toxic Equivalent (TEQ) was lower when using 20% biodiesel, in comparison with 5% biodiesel on the SCR system, reaffirming the low toxicity emission using higher percentage biodiesel. The data also reveal that use of SCR, on its own, suppress the Nitro-PAHs compounds. In general, the use of larger fractions of biodiesel (B20) coupled with the SCR aftertreatment showed the lowest PAHs and Nitro-PAHs emissions, meaning lower toxicity and, consequently, a potential lower risk to human health. From the emission point of view, the results of this work also demonstrated the viability of the Biodiesel programs, in combination with the SCR systems, which does not require any engine adaptation and is an economical alternative for the countries (Brazil, China, Russia, India) that have not adopted Euro VI emission standards.

Gasoline Particulate Filters as an Effective Tool to Reduce Particulate and Polycyclic Aromatic Hydrocarbon Emissions from Gasoline Direct Injection (GDI) Vehicles: A Case Study with Two GDI Vehicles

We assessed the gaseous, particulate, and genotoxic pollutants from two current technology gasoline direct injection vehicles when tested in their original configuration and with a catalyzed gasoline particulate filter (GPF). Testing was conducted over the LA92 and US06 Supplemental Federal Test Procedure (US06) driving cycles on typical California E10 fuel. The use of a GPF did not show any fuel economy and carbon dioxide (CO₂) emission penalties, while the emissions of total hydrocarbons (THC), carbon monoxide (CO), and nitrogen oxides (NOx) were generally reduced. Our results showed dramatic reductions in particulate matter (PM) mass, black carbon, and total and solid particle number emissions with the use of GPFs for both vehicles over the LA92 and US06 cycles. Particle size distributions were primarily bimodal in nature, with accumulation mode particles dominating the distribution profile and their concentrations being higher during the cold-start period of the cycle. Polycyclic aromatic hydrocarbons (PAHs) and nitrated PAHs were quantified in both the vapor and particle phases of the PM, with the GPF-equipped vehicles practically eliminating most of these species in the exhaust. For the stock vehicles, 2-3 ring compounds and heavier 5-6 ring compounds were observed in the PM, whereas the vapor phase was dominated mostly by 2-3 ring aromatic compounds.

Temperature and Driving Cycle Significantly Affect Carbonaceous Gas and Particle Matter Emissions from Diesel Trucks

The present study examines the effects of fuel [an ultralow sulfur diesel (ULSD) versus a 20% v/v soy-based biodiesel-80% v/v petroleum blend (B20)], temperature, load, vehicle, driving cycle, and active regeneration technology on gas- and particle-phase carbon emissions from light and medium heavy-duty diesel vehicles (L/MHDDV). The study is performed using chassis dynamometer facilities that support low-temperature operation (-6.7 °C versus 21.7 °C) and heavy loads up to 12 000 kg. Organic and elemental carbon (OC-EC) composition of aerosol particles is determined using a thermal-optical technique. Gas- and particle-phase semivolatile organic compound (SVOC) emissions collected using traditional filter and polyurethane foam sampling media are analyzed using advanced gas chromatograpy/mass spectrometry methods. Study-wide OC and EC emissions are 0.735 and 0.733 mg/km, on average. The emissions factors for diesel vehicles vary widely, and use of a catalyzed diesel particle filter (CDPF) device generally mutes the carbon particle emissions in the exhaust, which contains ~90% w/w gas-phase matter. Interestingly, replacing ULSD with B20 did not significantly influence SVOC emissions, for which sums range from 0.030 to 9.4 mg/km for the L/MHDDVs. However, both low temperature and vehicle cold-starts significantly increase SVOCs in the exhaust. Real-time particle measurements indicate vehicle regeneration technology did influence emissions, although regeneration effects went unresolved using bulk chemistry techniques. A multistudy comparison of the toxic particle-phase polycyclic aromatic hydrocarbons (PAHs; molecular weight (MW) ≥ 252 amu) in diesel exhaust indicates emission factors that span up to 8 orders of magnitude over the past several decades. This study observes conditions under which PAH compounds with MW ≥ 252 amu appear in diesel particles downstream of the CDPF and can even reach low-end concentrations reported earlier for much larger HDDVs with poorly controlled exhaust streams. This rare observation suggests that analysis of PAHs in particles emitted from modern L/MHDDVs may be more complex than recognized previously.

Inland navigation: PAH inventories in soil and vegetation after EU fuel regulation 2009/30/EC

In January 2011, fuel quality in inland water vessels was changed by EU regulation 2009/30/EC, aiming at improving air quality along waterways. We hypothesized that the implementation of this regulation both lowered the total deposition of polycyclic aromatic hydrocarbons (PAHs) and changed their composition in river valleys. We analyzed parent-, alkylated- and thio-PAHs in soil and vine leaves, at two waterways (Rhine and Moselle, Germany), as well as in one ship-free reference area (Ahr, Germany). Samples were taken annually (2010-2013) in transects perpendicular to the rivers. We did not find any relation of PAH concentration and composition on vine leaves to inland navigation, likely because atmospheric exchange processes distorted ship-specific accumulation patterns. We did find, however, an accumulation of ship-borne PAHs in topsoil near the waterways (1543±788 and 581±252ngg^-1 at Moselle and Rhine, respectively), leading to larger PAH concentrations at the Moselle Valley than at the reference area (535±404ngg^-1) prior to EU fuel regulation. After fuel regulation, the PAH concentrations decreased in topsoils of the Moselle and Rhine Valley by 35±9 and 62±28%, respectively. These changes were accompanied by increasing proportions of dibenzothiophene (DBT) and low molecular weight PAHs. Both, changes in PAH concentrations and composition were traceable within 200 and 350m distance to the river front of Moselle and Rhine, respectively, and likely favored by erosion of topsoil in vineyards. We conclude that the EU regulation was effective in improving soil and thus also air quality within only three years. The impact was greater and spatially more relevant at the Rhine, which may be attributed to the larger traffic volume of inland navigation.

On-road traffic emissions of polycyclic aromatic hydrocarbons and their oxy- and nitro- derivative compounds measured in road tunnel environments

Vehicular emissions are a key source of polycyclic aromatic compounds (PACs), including polycyclic aromatic hydrocarbons (PAHs) and their oxygenated (OPAH) and nitrated (NPAH) derivatives, in the urban environment. Road tunnels are a useful environment for the characterisation of on-road vehicular emissions, providing a realistic traffic fleet and a lack of direct sunlight, chemical reactivity and non-traffic sources. In the present investigation the concentrations of selected PAHs, OPAHs and NPAHs have been measured in the Parc des Princes Tunnel in Paris (PdPT, France), and at the Queensway Road Tunnel and an urban background site in Birmingham (QT, U.K). A higher proportion of semi-volatile (3-4 ring) PAH, OPAH and NPAH compounds are associated with the particulate phase compared with samples from the ambient environment. A large (~85%) decline in total PAH concentrations is observed between 1992 and 2012 measurements in QT. This is attributed primarily to the introduction of catalytic converters in the U.K as well as increasingly stringent EU vehicle emissions legislation. In contrast, NPAH concentrations measured in 2012 are similar to those measured in 1996. This observation, in addition to an increased proportion of (Phe+Flt+Pyr) in the observed PAH burden in the tunnel, is attributed to the increased number of diesel passenger vehicles in the U.K during this period. Except for OPAHs, comparable PAH and NPAH concentrations are observed in both investigated tunnels (QT and PdP). Significant differences are shown for specific substances between PAC chemical profiles in relation with the national traffic fleet differences (33% diesel passenger cars in U.K. vs 69% in France and up to 80% taking into account all vehicle categories). The dominating and sole contribution of 1-Nitropyrene observed in the PdPT NPAH profile strengthens the promising use of this compound as a diesel exhaust marker for PM source apportionment studies.

Airborne Dioxins, Furans, and Polycyclic Aromatic Hydrocarbons Exposure to Military Personnel in Iraq

OBJECTIVES

The objective of this study was to use ambient polycyclic aromatic hydrocarbon (PAH), polychlorinated dibenzo-p-dioxins (PCDD), and polychlorinated dibenzofurans (PCDF) concentrations measured at Joint Base Balad in Iraq in 2007 to identify the sources of these species and their spatial patterns.

METHODS

The ratios of the measured species were compared with literature data for likely emission sources. Using the multiple site measurements on specific days, contour maps have been drawn using inverse distance weighting (IDW).

RESULTS

These analyses suggest multiple sources, including the burn pit (primarily a source of PCDD/PCDFs), the transportation field (primarily as source of PAHs), and other sources of PAHs that include aircraft, space heating, and diesel power generation.

CONCLUSIONS

The nature and locations of the sources were identified. PCDD/PCDFs were emitted by the burn pit. Multiple PAH sources exist across the base.

Intermediate Volatility Organic Compound Emissions from On-Road Diesel Vehicles: Chemical Composition, Emission Factors, and Estimated Secondary Organic Aerosol Production

Emissions of intermediate-volatility organic compounds (IVOCs) from five on-road diesel vehicles and one off-road diesel engine were characterized during dynamometer testing. The testing evaluated the effects of driving cycles, fuel composition and exhaust aftertreatment devices. On average, more than 90% of the IVOC emissions were not identified on a molecular basis, instead appearing as an unresolved complex mixture (UCM) during gas-chromatography mass-spectrometry analysis. Fuel-based emissions factors (EFs) of total IVOCs (speciated + unspeciated) depend strongly on aftertreatment technology and driving cycle. Total-IVOC emissions from vehicles equipped with catalyzed diesel particulate filters (DPF) are substantially lower (factor of 7 to 28, depending on driving cycle) than from vehicles without any exhaust aftertreatment. Total-IVOC emissions from creep and idle operations are substantially higher than emissions from high-speed operations. Although the magnitude of the total-IVOC emissions can vary widely, there is little variation in the IVOC composition across the set of tests. The new emissions data are combined with published yield data to investigate secondary organic aerosol (SOA) formation. SOA production from unspeciated IVOCs is estimated using surrogate compounds, which are assigned based on gas-chromatograph retention time and mass spectral signature of the IVOC UCM. IVOCs contribute the vast majority of the SOA formed from exhaust from on-road diesel vehicles. The estimated SOA production is greater than predictions by previous studies and substantially higher than primary organic aerosol. Catalyzed DPFs substantially reduce SOA formation potential of diesel exhaust, except at low speed operations.

Elements and polycyclic aromatic hydrocarbons in exhaust particles emitted by light-duty vehicles

The main purpose of this work was to evaluate the chemical composition of particulate matter (PM) emitted by eight different light-duty vehicles. Exhaust samples from petrol and diesel cars (Euro 3 to Euro 5) were collected in a chassis dynamometer facility. To simulate the real-world driving conditions, three ARTEMIS cycles were followed: road, to simulate a fluid traffic flow and urban with hot and cold starts, to simulate driving conditions in cities. Samples were analysed for the water-soluble ions, for the elemental composition and for polycyclic aromatic hydrocarbons (PAHs), respectively, by ion chromatography, inductively coupled plasma atomic emission spectroscopy (ICP-AES), inductively coupled plasma mass spectrometry (ICP-MS) and gas chromatography-mass spectrometry (GC-MS). Nitrate and phosphate were the major water-soluble ions in the exhaust particles emitted from diesel and petrol vehicles, respectively. The amount of material emitted is affected by the vehicle age. For vehicles ≥Euro 4, most elements were below the detection limits. Sodium, with emission factors in the ranges 23.5-62.4 and 78.2-227μg km(-1), for petrol and diesel Euro 3 vehicles, respectively, was the major element. The emission factors of metallic elements indicated that diesel vehicles release three to five times more than petrol automobiles. Element emissions under urban cycles are higher than those found for on-road driving, being three or four times higher, for petrol vehicles, and two or three times, for diesel vehicles. The difference between cycles is mainly due to the high emissions for the urban cycle with hot start-up. As registered for elements, most of the PAH emissions for vehicles ≥Euro 4 were also below the detection limits. Regardless of the vehicle models or driving cycles, the two- to four-ring PAHs were always dominant. Naphthalene, with emission factors up to 925 μg km(-1), was always the most abundant PAH. The relative cancer risk associated with naphthalene was estimated to be up to several orders of magnitude higher than any of the chemical species found in the PM phase. The highest PAH emission factors were registered for diesel-powered vehicles. The condition of the vehicle can exert a decisive influence on both element and PAH emissions.

Mitigation of PAH and nitro-PAH emissions from nonroad diesel engines

More stringent emission requirements for nonroad diesel engines introduced with U.S. Tier 4 Final and Euro Stage IV and V regulations have spurred the development of exhaust aftertreatment technologies. In this study, several aftertreatment configurations consisting of diesel oxidation catalysts (DOC), diesel particulate filters (DPF), Cu zeolite-, and vanadium-based selective catalytic reduction (SCR) catalysts, and ammonia oxidation (AMOX) catalysts are evaluated using both Nonroad Transient (NRTC) and Steady (8-mode NRSC) Cycles in order to understand both component and system-level effects of diesel aftertreatment on emissions of polycyclic aromatic hydrocarbons (PAH) and their nitrated derivatives (nitro-PAH). Emissions are reported for four configurations including engine-out, DOC+CuZ-SCR+AMOX, V-SCR+AMOX, and DOC+DPF+CuZ-SCR+AMOX. Mechanisms responsible for the reduction, and, in some cases, the formation of PAH and nitro-PAH compounds are discussed in detail, and suggestions are provided to minimize the formation of nitro-PAH compounds through aftertreatment design optimizations. Potency equivalency factors (PEFs) developed by the California Environmental Protection Agency are then applied to determine the impact of aftertreatment on PAH-derived exhaust toxicity. Finally, a comprehensive set of exhaust emissions including criteria pollutants, NO2, total hydrocarbons (THC), n-alkanes, branched alkanes, saturated cycloalkanes, aromatics, aldehydes, hopanes and steranes, and metals is provided, and the overall efficacy of the aftertreatment configurations is described. This detailed summary of emissions from a current nonroad diesel engine equipped with advanced aftertreatment can be used to more accurately model the impact of anthropogenic emissions on the atmosphere.

Comparative mutagenicity and genotoxicity of particles and aerosols emitted by the combustion of standard vs. rapeseed methyl ester supplemented bio-diesel fuels: impact of after treatment devices: oxidation catalyst and particulate filter

Diesel exhausts are partly responsible for the deleterious effects on human health associated with urban pollution, including cardiovascular diseases, asthma, COPD, and possibly lung cancer. Particulate fraction has been incriminated and thus largely investigated for its genotoxic properties, based on exposure conditions that are, however, not relevant for human risk assessment. In this paper, original and more realistic protocols were used to investigate the hazards induced by exhausts emitted by the combustion of standard (DF0) vs. bio-diesel fuels (DF7 and DF30) and to assess the impact of exhaust treatment devices (DOC and DPF). Mutagenicity and genotoxicity were evaluated for (1) resuspended particles ("off line" exposure that takes into account the bioavailability of adsorbed chemicals) and for (2) the whole aerosols (particles+gas phase components) under continuous flow exposure ("on line" exposure). Native particles displayed mutagenic properties associated with nitroaromatic profiles (YG1041), whereas PAHs did not seem to be involved. After DOC treatment, the mutagenicity of particles was fully abolished. In contrast, the level of particle deposition was low under continuous flow exposure, and the observed mutagenicity in TA98 and TA102 was thus attributable to the gas phase. A bactericidal effect was also observed in TA102 after DOC treatment, and a weak but significant mutagenicity persisted after DPF treatment for bio-diesel fuels. No formation of bulky DNA-adducts was observed on A549 cells exposed to diesel exhaust, even in very drastic conditions (organic extracts corresponding to 500 μg equivalent particule/mL, 48 h exposure). Taken together, these data indicate that the exhausts issued from the bio-diesel fuels supplemented with rapseed methyl ester (RME), and generated by current diesel engines equipped with after treatment devices are less mutagenic than older ones. The residual mutagenicity is linked to the gas phase and could be due to pro-oxydants, mainly for RME-supplemented fuels.

Oxidative stress and aromatic hydrocarbon response of human bronchial epithelial cells exposed to petro- or biodiesel exhaust treated with a diesel particulate filter

The composition of diesel exhaust has changed over the past decade due to the increased use of alternative fuels, like biodiesel, and to new regulations on diesel engine emissions. Given the changing nature of diesel fuels and diesel exhaust emissions, a need exists to understand the human health implications of switching to "cleaner" diesel engines run with particulate filters and engines run on alternative fuels like biodiesel. We exposed well-differentiated normal human bronchial epithelial cells to fresh, complete exhaust from a diesel engine run (1) with and without a diesel particulate filter and (2) using either traditional petro- or alternative biodiesel. Despite the lowered emissions in filter-treated exhaust (a 91-96% reduction in mass), significant increases in transcripts associated with oxidative stress and polycyclic aromatic hydrocarbon response were observed in all exposure groups and were not significantly different between exposure groups. Our results suggest that biodiesel and filter-treated diesel exhaust elicits as great, or greater a cellular response as unfiltered, traditional petrodiesel exhaust in a representative model of the bronchial epithelium.