Phase and size distribution of polycyclic aromatic hydrocarbons in diesel and gasoline vehicle emissions

Emission profiles, source identifications, and health risk of polycyclic aromatic hydrocarbons (PAHs) in a road tunnel located in Xi'an, China

Understanding the sources and characteristics of PM2.5-bound PAHs from traffic-related pollution can provide valuable data for mitigating air contamination from traffic in local urban regions. However, little information on PAHs is available regarding the typical arterial highway-Qinling Mountains No.1 tunnel in Xi'an. We estimated the profiles, sources, and emission factors of PM2.5-bound PAHs in this tunnel. The total PAH concentrations were 22.78 ng·m-3 and 52.80 ng·m-3 at the tunnel middle and exit, which were 1.09 and 3.84 times higher than that at the tunnel entrance. Pyr, Flt, Phe, Chr, BaP, and BbF were the dominant PAH species (representing approximately 78.01% of total PAHs). The four rings PAHs were dominant (58%) among the total PAH concentrations in PM2.5. The results demonstrated that diesel and gasoline vehicles exhaust emissions contributed 56.81% and 22.60% to the PAHs, respectively, while the corresponding value for together brakes, tyre wear, and road dust was 20.59%. The emission factors of total PAHs were 29.35 μg·veh-1·km-1, and emission factors of 4 rings PAHs were significantly higher than those of the other PAHs. The sum of ILCR was estimated to be 1.41×10-4, which accorded with acceptable level of cancer risk (10-6-10-4), PAHs should not ignored as they still affect the public health of inhabitants. This study shed light on PAH profiles and traffic-related sources in the tunnel, thereby facilitating the assessment of control measures targeting PAHs in local areas.

Emission factors for a biofuel impacted fleet in south America's largest metropolitan area

The Metropolitan Area of São Paulo (MASP) is among the largest urban areas in the Southern Hemisphere. Vehicular emissions are of great concern in metropolitan areas and MASP is unique due to the use of biofuels on a large scale (sugar-cane ethanol and biodiesel). In this work, tunnel measurements were employed to assess vehicle emissions and to calculate emission factors (EFs) for heavy-duty and light-duty vehicles (HDVs and LDVs). The EFs were determined for particulate matter (PM) and its chemical compounds. The EFs obtained for 2018 were compared with previous tunnel experiments performed in the same area. An overall trend of reduction of fine and coarse PM, organic carbon (OC), and elemental carbon (EC) EFs for both LDVs and HDVs was observed if compared to those observed in past years, suggesting the effectiveness of vehicular emissions control policies implemented in Brazil. A predominance of Fe, Cu, Al, and Ba metals emission was observed for the LDV fleet in the fine fraction. Cu presented higher emissions than two decades ago, which was associated with the increased use of ethanol fuel in the region. For HDVs, Zn and Pb were mostly emitted in the fine mode and were linked with lubricating oil emissions from diesel vehicles. A predominance in the emission of three- and four-ring polycyclic aromatic hydrocarbons (PAHs) for HDVs and five-ring PAHs for LDVs agreed with what was observed in previous studies. The use of biofuels may explain the lower PAH emissions for LDVs (including carcinogenic BaP) compared to those observed in other countries. The tendency observed was that LDVs emit higher amounts of carcinogenic species. The use of these real EFs in air quality modeling resulted in more accurate simulations of PM concentrations, showing the importance of updating data with real-world measurements.

Emission factors for polycyclic aromatic hydrocarbons from laboratory biomass-burning and their chemical transformations during aging in an oxidation flow reactor

Atmospheric polycyclic aromatic hydrocarbons (PAHs) can be emitted from different combustion sources including domestic biomass burning, internal combustion engines, and biomass burning (BB) in wild, prescribed, and agricultural fires. With climate warming and consequent global increases in frequency and severity of wildfires, BB is a dominant source of PAHs emitted into the atmosphere. In this study, six globally and regionally important and representative fuels (Alaskan peat, Moscow peat, Pskov peat, eucalyptus, Malaysian peat, and Malaysian agricultural peat) were burned under controlled conditions in the combustion chamber facility at the Desert Research Institute (DRI, Reno, NV, USA). Gas- and particle-phase BB emissions were aged in an oxidation flow reactor (OFR) to mimic five to sevendays of atmospheric aging. To sample gas- and particle-phase BB emissions, fresh and OFR-aged biomass-burning aerosols were collected on Teflon-impregnated glass fiber filters (TIGF) in tandem with XAD resin media for organic carbon speciation. The objectives of this study were to i) quantify the emission factors for 113 PAHs emitted from the combustion of the six selected fuels, ii) characterize the distribution of PAH compounds between gas and particle phases for these fuels, iii) identify the changes in PAHs during OFR-aging, and iv) evaluate toxicity potential with characterized compounds. We found that combustion emissions of gas-phase PAHs were more abundant (>80 % by mass) than particle-phase PAHs, for emissions from all combusted fuels. The mass fraction of substituted napthalenes in Moscow peat and Malaysian peat emissions were ∼70 % & 84 %, respectively, whereas in Eucalyptus the same fraction was <50 %, which indicates that these substituted compounds can be used as tracers for peat emissions. Mass concentrations of gas- and particle-phase PAHs were reduced by ∼70 % after OFR oxidation. However, the understanding of the fate of PAHs during OFR oxidation requires further investigations. Our results also indicate that the PAH toxicity of BB samples would be underestimated by 10-100 times if only the BaPeq for the 16 US EPA priority PAHs in the particle phase are included.

Comprehensive treatment strategy for diesel truck exhaust

At present, diesel vehicles still play an irreplaceable role in the traditional energy field in China. Diesel vehicle exhaust contains hydrocarbons, carbon monoxide, nitrogen oxides, and particulate matter, which can lead to haze weather, photochemical smog, and the greenhouse effect; endanger human health; and damage the ecological environment. In 2020, the number of motor vehicles in China reached 372 million, and the number of automobiles reached 281 million, of which 20.92 million are diesel vehicles, accounting for only 5.6% of the number of motor vehicles and 7.4% of the number of automobiles. Nevertheless, diesel vehicles emitted 88.8% of nitrogen oxides and 99% of particulate matter in total vehicle emissions. Diesel vehicles, especially diesel trucks, have become the top priority of motor vehicle pollution control. However, there are few reviews on the comprehensive treatment of diesel vehicle exhaust. This review provides an overview of exhaust gas composition, hazards, and treatment techniques. Phytoremediation, three-way catalytic conversion, rare earth catalytic degradation, and nanoscale TiO₂ catalytic degradation are briefly described.

Environmental and health risk implications of unregulated emissions from advanced biofuels in a Euro 6 engine

The use of conventional and advanced biofuels is part of the efforts to reduce greenhouse gases and harmful exhaust gaseous emissions. This study investigates the unregulated emissions in gas and particles from a Euro 6b diesel engine, operated with four unconventional and advanced biofuels (two hydrogenated terpenic biofuels, a polyoxymethylene dimethyl ether, and a glycerol-derived biofuel), blended with diesel fuel and pure hydrotreated vegetable oil as base biofuel. The engine was operated following WLTC starting from cold-engine conditions. Gas phase samples were collected at each phase of the driving cycle and particulate matter (PM) samples were collected from a dilution tunnel at the end of the driving cycle. A total of 16 PAH and 13 carbonyls were analyzed. In addition, the apoptotic index induced by gas and particle emissions was determined. In the gaseous phase, the total PAH and carbonyl emission factors were higher at the low-speed phase for all fuels. Gas-phase PAH emission factors exceeded particle-bound PAH. Carbonyl emission factors ranged from 0.12 ± 0.012 to 25.3 ± 4.2 mg/km, markedly exceeding gaseous PAH emissions, which ranged from 20.7 ± 1.5 to 51.7 ± 8.9 μg/km. Diesel fuel exhibited the highest carbonyl emissions and its blend with 20% of hydrogenated turpentine exhibited the highest PAH emissions at the end of the WLTC, both due to high emissions at the low-speed phase. Although particle-bound PAH comprise only a small fraction of total PAH emissions, both phases (gas and particles) contributed approximately equal to the toxicity associated with carcinogenic PAH. The apoptotic cells percentage increased in a dose-dependent manner and was significantly higher in cells exposed to gas phase-derived samples. The apoptotic index induced by particulate matter samples did not show a concentration-response effect for any of the fuels.

Good and bad get together: Inactivation of SARS-CoV-2 in particulate matter pollution from different fuels

Air pollution and associated particulate matter (PM) affect environmental and human health worldwide. The intense vehicle usage and the high population density in urban areas are the main causes of this public health impact. Epidemiological studies have provided evidence on the effect of air pollution on airborne SARS-CoV-2 transmission and COVID-19 disease prevalence and symptomatology. However, the causal relationship between air pollution and COVID-19 is still under investigation. Based on these results, the question addressed in this study was how long SARS-CoV-2 survives on the surface of PM from different origin to evaluate the relationship between fuel and atmospheric pollution and virus transmission risk. The persistence and viability of SARS-CoV-2 virus was characterized in 5 engine exhaust PM and 4 samples of atmospheric PM₁₀. The results showed that SARS-CoV-2 remains on the surface of PM₁₀ from air pollutants but interaction with engine exhaust PM inactivates the virus. Consequently, atmospheric PM₁₀ levels may increase SARS-CoV-2 transmission risk thus supporting a causal relationship between these factors. Furthermore, the relationship of pollution PM and particularly engine exhaust PM with virus transmission risk and COVID-19 is also affected by the impact of these pollutants on host oxidative stress and immunity. Therefore, although fuel PM inactivates SARS-CoV-2, the conclusion of the study is that both atmospheric and engine exhaust PM negatively impact human health with implications for COVID-19 and other diseases.

Investigation of PAHs, nitrated PAHs and oxygenated PAHs in PM10 urban aerosols. A comprehensive data analysis

Polycyclic aromatic compounds (PACs) in particulate matter contribute considerably to the health risk of air pollution. As such, we have optimized a method to determine the levels of polycyclic aromatic hydrocarbons, especially nitrated and oxygenated polycyclic aromatic hydrocarbons, in samples of PM₁₀ particulate matter using microwave-assisted extraction (MAE) and gas chromatography coupled to a triple quadrupole mass spectrometer (GC-MS/MS). The proposed method was applied to the analysis of real samples collected in the urban area of Ciudad Real (Spain) during one year. The median total concentrations of eighteen PAHs (∑PAHs) and seven OPAHs (∑OPAHs) were 0.54 and 0.23 ng m^-3, respectively, with the corresponding value for NPAH (∑NPAHs) being 0.03 ng m^-3 (only detected in 40% of samples). A clear seasonal trend was observed, with higher levels in the cold season and lower in the warm season for ∑PAHs. The same effect was observed for ∑OPAHs, which exhibited a median concentration of 0.72 ng m^-3 in the cold season and 0.10 ng m^-3 in the warm season, and for ∑NPAH, which exhibited a median of 0.04 ng m^-3 in the cold season but were not detected in the warm season. Molecular diagnostic ratios and PCA (principal component analysis) showed a predominantly traffic origin for PACs. The sources of PAHs also depend on meteorological conditions and/or atmospheric reactions, as confirmed by means of statistical analysis. The ∑OPAH/∑PAH and ∑NPAH/∑PAH ratios were higher in the cold season than the warm season, thus suggesting that PAH derivatives originated from primary combustion emission sources together with their parent PAHs. The concentration range found for benzo(a)pyrene was 0.006-0.542 ng m^-3, which is below the threshold value of 1 ng m^-3 established in European legislation as the annual average value. The lifetime lung risk from inhalation of PM₁₀-bound PACs was estimated to be six cancer cases per million people using the World Health Organization method.

The oxidative potential of fresh and aged elemental carbon-containing airborne particles: a review

Elemental carbon is often found in ambient particulate matter (PM), and it contributes to the PM's oxidative potential (OP) and thus poses great health concerns. Previous review articles mainly focused on the methodologies in evaluating OP in PM and its relationship with selected chemical constituents, including metal ions, PAHs, and inorganic species. In recent years, growing attention has been paid to the effect of atmospheric aging processes on the OP of EC-containing airborne particles (ECCAPs). This review investigates more than 150 studies concerning the OP measurements and physico-chemical properties of both fresh and aged ECCAPs such as laboratory-generated elemental carbon (LGEC), carbon black (CB), soot (black carbon), and engineered carbon-containing nanomaterials (ECCBNs). Specifically, we summarize the characteristics of water-soluble and insoluble organic species, PAHs, quinone, and oxygen-containing functional groups (OFGs), and EC crystallinity. Both water-soluble organic carbon (WSOC) and water-insoluble organic carbon (WIOC) contribute to the OP. Low molecular weight (MW) PAHs show a higher correlation with OP than high MW PAHs. Furthermore, oxidative aging processes introduce OFGs, where quinone (CO) and epoxide (O-C-O) increase the OP of ECCAPs. In contrast, carboxyl (-COOH) and hydroxyl (-OH) slightly change the OP. The low crystallinity of EC favors the oxygen addition and forms active OFG quinone, thus increasing the OP. More detailed analyses for the EC microstructures and the organic coatings are needed to predict the OP of ECCAPs.

Composition of aerosols from thermal degradation of flavors used in ENDS and tobacco products

Aim: The cardiovascular toxicity of unheated and heated flavorants and their products as commonly present in electronic cigarette liquids (e-liquids) was evaluated previously in vitro. Based on the results of in vitro assays, cinnamaldehyde, eugenol, menthol, and vanillin were selected to conduct a detailed chemical analysis of the aerosol generated following heating of each compound both at 250 and 750 °C. Materials and Methods: Each flavoring was heated in a drop-tube furnace within a quartz tube. The combustion atmosphere was captured using different methods to enable analysis of 308 formed compounds. Volatile organic compounds (VOCs) were captured with an evacuated Summa canister and assayed via gas chromatography interfaced with mass spectrometry (GC-MS). Carbonyls (aldehydes and ketones) were captured using a 2,4-dinitrophenylhydrazine (DNPH) cartridge and assayed via a high-performance liquid chromatography-ultra-violet (HPLC-UV) assay. Polyaromatic hydrocarbons (PAHs) were captured using an XAD cartridge and filter, and extracts were assayed using GC-MS/MS. Polar compounds were assayed after derivatization of the XAD/filter extracts and analyzed via GC-MS. Conclusion: At higher temperature, both cinnamaldehyde and menthol combustion significantly increased formaldehyde and acetaldehyde levels. At higher temperature, cinnamaldehyde, eugenol, and menthol resulted in increased benzene concentrations. At low temperature, all four compounds led to higher levels of benzoic acid. These data show that products of thermal degradation of common flavorant compounds vary by flavorant and by temperature and include a wide variety of harmful and potentially harmful constituents (HPHCs).

Traffic-related polycyclic aromatic hydrocarbons (PAHs) occurrence in a tropical environment

Traffic-related PAH emissions over the urban area of Natal, Brazil, have shown a significant increase because of automobile usage and have become a major concern due to their potential effects on human health and the environment. Therefore, this research measured PAH contamination on major roads and river compartments in a tropical catchment (Pitimbu River) over an expanding urban area. Road PAH concentrations spanned from 692 to 2098 ng g^-1 and suggest the predominance of heavy (diesel-powered) and light-duty (gasoline plus alcohol-powered) vehicle emission sources. High concentrations of naphthalene (515 ng g^-1) and acenaphthylene (145 ng g^-1) were found in river sediments, indicating oil-related spillage and low-temperature combustion sources. Diagnostic ratios indicated the prevalence of biomass, coal and petroleum combustion processes and refined oil products. The ecological risk assessment indicated an ecological contamination risk ranging between low and moderate because of naphthalene and acenaphthylene concentrations higher than ERL threshold values. Toxicity risks caused by PAHs were assessed by using the BaP-equivalent carcinogenic power (BaPE). Results indicated that both RDS and riverbed sediment samples are at low toxicity risk.

Using a hybrid approach to apportion potential source locations contributing to excess cancer risk of PM2.5-bound PAHs during heating and non-heating periods in a megacity in the Middle East

Polycyclic aromatic hydrocarbons (PAHs) represent one of the major toxic pollutants associated with PM_2.5 with significant human health and climate effects. Because of local and long-range transport of atmospheric PAHs to receptor sites, higher global attentions have been focused to improve PAHs pollution emission management. In this study, PM_2.5 samples were collected at three urban sites located in the capital of Iran, Tehran, during the heating and non-heating periods (H-period and NH-period). The US EPA 16 priority PAHs were analyzed and the data were processed to the following detailed aims: (i) investigate the H-period and NH-period variations of PM_2.5 and PM_2.5-bound PAHs concentrations; (ii) identify the PAHs sources and the source locations during the two periods; (iii) carry out a source-specific excess cancer risk (ECR) assessment highlighting the potential source locations contributing to the ECR using a hybrid approach. Total PAHs (TPAHs) showed significantly higher concentrations (1.56-1.89 times) during the H-period. Among the identified PAHs compounds, statistically significant periodical differences (p-value < 0.05) were observed only between eight PAHs species (Nap, BaA, Chr, BbF, BkF, BaP, IcdP, and DahA) at all three sampling sites which can be due to the significant differences of PAHs emission sources during H and NH-periods. High molecular weight (HMW) PAHs accounted for 52.7% and 46.8% on average of TPAHs during the H-period and NH-period, respectively. Positive matrix factorization (PMF) led to identifying four main PAHs sources including industrial emissions, petrogenic emissions, biomass burning and natural gas emissions, and vehicle exhaust emissions. Industrial and petrogenic emissions exhibited the highest contribution (19.8%, 27.2%, respectively) during the NH-period, while vehicle exhaust and biomass burning-natural gas emissions showed the largest contribution (40.7%, 29.6%, respectively) during the H-period. Concentration weighted trajectory (CWT) on factor contributions was used for tracking the potential locations of the identified sources. In addition to local sources, long-range transport contributed to a significant fraction of TPHAs in Tehran both during the H- and NH-periods. Source-specific carcinogenic risks assessment apportioned vehicle exhaust (44.2%, 2.52 × 10^-4) and biomass burning-natural gas emissions (33.9%, 8.31 × 10^-5) as the main cancer risk contributors during the H-period and NH-period, respectively. CWT maps pointed out the different distribution patterns associated with the cancer risk from the identified sources. This will allow better risk management through the identification of priority PAHs sources.

On the nature of polycyclic aromatic hydrocarbons associated with sporting walkways dust: Concentrations, sources and relative health risk

Sporting walkways (SW) are a new innovation which may prove popular in many cities. As there is currently no information on possible health risks associated with their use, concentrations of polycyclic aromatic hydrocarbons (PAHs) associated with deposited dust sampled on SW in Jeddah, Saudi Arabia, have been measured and interpreted in relation to sources and cancer risk. The average ∑PAHs (16 compounds) ranged between 1357 ng/g in residential areas and 3764 ng/g in central urban areas, with suburban areas between. The congener profile and diagnostic ratios of PAHs indicate a predominant source associated with petroleum combustion (pyrogenic source), most probably vehicular emissions. Carcinogenic potential is estimated from the sum of carcinogenic compound concentrations weighted by their individual potency relative to benzo(a)pyrene, and is found to be similar to household dust sampled in the same city, and lower than many other indoor and outdoor (road) dusts sampled across the world.

One-year measurements of secondary organic aerosol (SOA) markers in the Paris region (France): Concentrations, gas/particle partitioning and SOA source apportionment

Twenty-five biogenic and anthropogenic secondary organic aerosol (SOA) markers have been measured over a one-year period in both gaseous and PM₁₀ phases in the Paris region (France). Seasonal and chemical patterns were similar to those previously observed in Europe, but significantly different from the ones observed in America and Asia due to dissimilarities in source precursor emissions. Nitroaromatic compounds showed higher concentrations in winter due to larger emissions of their precursors originating from biomass combustion used for residential heating purposes. Among the biogenic markers, only isoprene SOA marker concentrations increased in summer while pinene SOA markers did not display any clear seasonal trend. The measured SOA markers, usually considered as semi-volatiles, were mainly associated to the particulate phase, except for the nitrophenols and nitroguaiacols, and their gas/particle partitioning (GPP) showed a low temperature and OM concentrations dependency. An evaluation of their GPP with thermodynamic model predictions suggested that apart from equilibrium partitioning between organic phase and air, the GPP of the markers is affected by processes suppressing volatility from a mixed organic and inorganic phase, such as enhanced dissolution in aerosol aqueous phase and non-equilibrium conditions. SOA marker concentrations were used to apportion secondary organic carbon (SOC) sources applying both, an improved version of the SOA-tracer method and positive matrix factorization (PMF) Total SOC estimations agreed very well between both models, except in summer and during a highly processed Springtime PM pollution event in which systematic underestimation by the SOA tracer method was evidenced. As a first approach, the SOA-tracer method could provide a reliable estimation of the average SOC concentrations, but it is limited due to the lack of markers for aged SOA together with missing SOA/SOC conversion fractions for several sources.

Molecular Speciation of Size Fractionated Particulate Water-Soluble Organic Carbon by Two-Dimensional Nuclear Magnetic Resonance (NMR) Spectroscopy

Particulate matter is associated with increased morbidity and mortality; its effects depend on particle size and chemical content. It is important to understand the composition and resultant toxicological profile of particulate organic compounds, the largest and most complex fraction of particulate matter. The objective of the study was to delineate the nuclear magnetic resonance (NMR) spectral fingerprint of the biologically relevant water-soluble organic carbon (WSOC) fraction of size fractionated urban aerosol. A combination of one and two-dimensional NMR spectroscopy methods was used. The size distribution of particle mass, water-soluble extract, non-exchangeable organic hydrogen functional types and specific biomarkers such as levoglucosan, methane sulfonate, ammonium and saccharides indicated the contribution of fresh and aged wood burning emissions, anthropogenic and biogenic secondary aerosol for fine particles as well as primary traffic exhausts and pollen for large particles. Humic-like macromolecules in the fine particle size range included branched carbon structures containing aromatic, olefinic, keto and nitrile groups and terminal carboxylic and hydroxyl groups such as terpenoid-like polycarboxylic acids and polyols. Our study show that 2D-NMR spectroscopy can be applied to study the chemical composition of size fractionated aerosols.

Immunopathological features of air pollution and its impact on inflammatory airway diseases (IAD)

Air pollution causes significant morbidity and mortality in patients with inflammatory airway diseases (IAD) such as allergic rhinitis (AR), chronic rhinosinusitis (CRS), asthma, and chronic obstructive pulmonary disease (COPD). Oxidative stress in patients with IAD can induce eosinophilic inflammation in the airways, augment atopic allergic sensitization, and increase susceptibility to infection. We reviewed emerging data depicting the involvement of oxidative stress in IAD patients. We evaluated biomarkers, outcome measures and immunopathological alterations across the airway mucosal barrier following exposure, particularly when accentuated by an infectious insult.

Size-segregated carbonaceous aerosols emission from typical vehicles and potential depositions in the human respiratory system

Particles emitted from five typical types of vehicles (including light-duty gasoline vehicles, LDG; heavy-duty gasoline vehicles, HDG; diesel buses, BUS; light-duty diesel vehicles, LDD and heavy-duty diesel vehicles, HDD) were collected with a dilution sampling system and an electrical low-pressure impactor (ELPI+, with particle sizes covering fourteen stages from 6 nm to 10 μm) on dynamometer benches. The mass concentrations and emission factors (EF) for organic carbon (OC) and elemental carbon (EC) were obtained with a DRI Model 2001 thermal/optical carbon analyzer. A respiratory deposition model was used to calculate the deposition fluxes of size-segregated carbonaceous aerosols in human respiratory system. Results indicated that the OC produced from LDG mainly existed in the size range of 2.5-10 μm, while EC from HDG enriched in 0.94-2.5 μm. For diesel vehicles, both OC and EC concentrations peaked at 0.094-0.25 μm. The OC/EC ratios for PM_2.5 varied from different types of vehicles, from 0.61 to 8.35. The primary emissions from LDD and HDD exhibited high OC/EC ratios (>3), suggesting that using OC/EC higher than 2 to indicate the formation of secondary organic aerosol (SOA) was not universal. The emission factors for OC and EC of LDG (HDG) in PM₁₀ were 1.78 (3.14) mg km^-1 and 0.88 (4.32) mg km^-1, respectively. The OC2 and OC3 were the main section (over 60%) of OC emitted from all the five types of vehicles. EC1 was the most abundant EC fraction of LDG (76.9%), while EC2 dominated for other types of vehicles (more than 62%). About 60% of the OC in ultrafine particles could be deposited in the alveoli. Diesel EC mainly could be deposited in the alveolar region. It is necessary to control the emission of ultrafine particles and diesel EC.

Discerning natural and anthropogenic organic matter inputs to salt marsh sediments of Ria Formosa lagoon (South Portugal)

Sedimentary organic matter (OM) origin and molecular composition provide useful information to understand carbon cycling in coastal wetlands. Core sediments from threors' Contributionse transects along Ria Formosa lagoon intertidal zone were analysed using analytical pyrolysis (Py-GC/MS) to determine composition, distribution and origin of sedimentary OM. The distribution of alkyl compounds (alkanes, alkanoic acids and alkan-2-ones), polycyclic aromatic hydrocarbons (PAHs), lignin-derived methoxyphenols, linear alkylbenzenes (LABs), steranes and hopanes indicated OM inputs to the intertidal environment from natural-autochthonous and allochthonous-as well as anthropogenic. Several n-alkane geochemical indices used to assess the distribution of main OM sources (terrestrial and marine) in the sediments indicate that algal and aquatic macrophyte derived OM inputs dominated over terrigenous plant sources. The lignin-derived methoxyphenol assemblage, dominated by vinylguaiacol and vinylsyringol derivatives in all sediments, points to large OM contribution from higher plants. The spatial distributions of PAHs (polyaromatic hydrocarbons) showed that most pollution sources were mixed sources including both pyrogenic and petrogenic. Low carbon preference indexes (CPI > 1) for n-alkanes, the presence of UCM (unresolved complex mixture) and the distribution of hopanes (C₂₉-C₃₆) and steranes (C₂₇-C₂₉) suggested localized petroleum-derived hydrocarbon inputs to the core sediments. Series of LABs were found in most sediment samples also pointing to domestic sewage anthropogenic contributions to the sediment OM.

Phase distribution of polycyclic aromatic hydrocarbons and their oxygenated and nitrated derivatives in the ambient air of a Brazilian urban area☆

Air quality in large cities has worsened in recent years as a consequence people's health is directly affected. Among the toxic compounds released to environmental air are polycyclic aromatic hydrocarbons (PAHs), nitrated PAHs (nitro-PAHs), and oxygenated PAHs (oxy-PAHs). Performant methods to analyze these compounds is necessary to enable adequate monitoring of air quality. Thus, this manuscript presents the development of a highly sensitive method to analyze PAHs, nitro-PAHs, and oxy-PAHs collected from ambient air (PM_2.5) and the gas phase for a period of one year in the urban area of Belo Horizonte, Brazil. PAHs and their derivatives were extracted by cold fiber solid phase microextraction (CF-SPME) and analyzed by gas chromatography coupled to mass spectrometry (GC/MS). The proposed method allows simultaneous analysis of 16 PAHs, nitro-PAHs and oxy-PAHs, presenting very good limits of detection and quantification, as well as appropriate precision and recovery. The results obtained for the period of one year allowed different studies. The compounds collected simultaneously from gas and particulate phase showed that total concentration of 16 PAHs were higher in the gas phase than in the particulate. On the other hand, nitro-PAHs and oxy-PAHs presented similar concentration in gas and particulate phases. The potential carcinogenicity of PAHs relative to benzo[a]pyrene showed benzo[a]pyrene equivalents of 0.49 ng m^-3. The estimated risk of lifetime lung cancer was 5 × 10^-5. Principal component analysis and diagnostic ratio was applied for source distribution indicating that burning of gasoline, diesel and biomass accounted for the PAHs profile in ambient air samples.

Nanodomains in cardiopulmonary disorders and the impact of air pollution

Air pollution is a major environmental threat and each year about 7 million people reported to die as a result of air pollution. Consequently, exposure to air pollution is linked to increased morbidity and mortality world-wide. Diesel automotive engines are a major source of urban air pollution in the western societies encompassing particulate matter and diesel exhaust particles (DEP). Air pollution is envisioned as primary cause for cardiovascular dysfunction, such as ischemic heart disease, cardiac dysrhythmias, heart failure, cerebrovascular disease and stroke. Air pollution also causes lung dysfunction, such as chronic obstructive pulmonary disease (COPD), asthma, idiopathic pulmonary fibrosis (IPF), and specifically exacerbations of these diseases. DEP induces inflammation and reactive oxygen species production ultimately leading to mitochondrial dysfunction. DEP impair structural cell function and initiate the epithelial-to-mesenchymal transition, a process leading to dysfunction in endothelial as well as epithelial barrier, hamper tissue repair and eventually leading to fibrosis. Targeting cyclic adenosine monophosphate (cAMP) has been implicated to alleviate cardiopulmonary dysfunction, even more intriguingly cAMP seems to emerge as a potent regulator of mitochondrial metabolism. We propose that targeting of the mitochondrial cAMP nanodomain bear the therapeutic potential to diminish air pollutant — particularly DEP — induced decline in cardiopulmonary function.

The association between the diesel exhaust particle exposure from bus emission and the tubular epithelial cell deformation of rats

The diesel vehicle emissions regarding particles have become a problem due to human health adversely. Especially ultrafine particles (diameter ≤ 100 nm) can deeply penetrate the human body leading to cell deformation. Investigation of the diesel ultrafine particle exposure to the cell deformation has become a challenge to build up understanding the impacts of ultrafine particles on human health. Moreover, the relationship between high exposure to diesel ultrafine particles and the deformation of the rat's tubular epithelial cells is not clear. In this study, we investigated the impact of the diesel ultrafine particle exposure to the rat's tubular cells. Three diesel busses were used as the sources of the particles, while 50 rats were used as the experimental animals. The diesel emission was filtered using an N95 particulate filter and a suction pump. The rats were exposed to the diesel ultrafine particle emission for 100 s with three different concentrations C₁, C₂, and C₃ for eight consecutive days. All rats were sacrificed on the day after exposures to examine the histological images. The results showed that the deformation level of the tubular epithelial cells was positively associated with the concentration of the ultrafine particles.

Drivers of Foliar Fungal Endophytic Communities of Kudzu (Pueraria montana var. lobata) in the Southeast United States

Fungal endophytes play important roles in plant fitness and plant–microbe interactions. Kudzu (Pueraria montana var. lobata) is a dominant, abundant, and highly aggressive invasive plant in the Southeast United States. Kudzu serves as a pathogen reservoir that impacts economically important leguminous crops. We conducted the first investigations on kudzu fungal endophytes (Illumina MiSeq—ITS2) to elucidate drivers of endophytic communities across the heart of the invasive range in the Southeast United States (TN, MS, AL, GA). We tested the impacts of multiple environmental parameters (Chlorophyll, NO3−, K+, soil pH, leaf area, host genotype, traffic intensity, and geographic location) on foliar endophyte communities. Endophytic communities were diverse and structured by many factors in our PerMANOVA analyses, but location, genotype, and traffic (proxy for pollution) were the strongest drivers of community composition (R2 = 0.152, p < 0.001, R2 = 0.129, p < 0.001, and R2 = 0.126, p < 0.001, respectively). Further, we examined the putative ecological interactions between endophytic fungi and plant pathogens. We identify numerous OTUs that are positively and strongly associated with pathogen occurrence, largely within the families Montagnulaceae and Tremellales incertae sedis. Taken together, these data suggest location, host genetics and local pollution play instrumental roles in structuring communities, and integrative plant management must consider these factors when developing management strategies.

Classroom Dust-Bound Polycyclic Aromatic Hydrocarbons in Jeddah Primary Schools, Saudi Arabia: Level, Characteristics and Health Risk Assessment

Data concerning polycyclic aromatic hydrocarbons (PAHs) in Jeddah's schools, Saudi Arabia, and their implications for health risks to children, is scarce. Classroom air conditioner filter dusts were collected from primary schools in urban, suburban and residential areas of Jeddah. This study aimed to assess the characteristics of classroom-dust-bound PAHs and the health risks to children of PAH exposure. Average PAH concentrations were higher in urban schools than suburban and residential schools. Benzo (b)fluoranthene (BbF), benzo(ghi)perylene (BGP), chrysene (CRY) and Dibenz[a,h]anthracene (DBA) at urban and suburban schools and BbF, BGP, fluoranthene (FLT) and indeno (1, 2, 3, -cd)pyrene (IND) at residential schools were the dominant compounds in classroom dust. PAHs with five aromatic rings were the most abundant at all schools. The relative contribution of the individual PAH compounds to total PAH concentrations in the classroom dusts of schools indicate that the study areas do share a common source, vehicle emissions. Based on diagnostic ratios of PAHs, they are emitted from local pyrogenic sources, and traffic is the significant PAH source, with more significant contributions from gasoline-fueled than from diesel cars. Based on benzo[a]pyrene equivalent (BaPequi) calculations, total carcinogenic activity (TCA) for total PAHs represent 21.59% (urban schools), 20.99% (suburban schools), and 18.88% (residential schools) of total PAH concentrations. DBA and BaP were the most dominant compounds contributing to the TCA, suggesting the importance of BaP and DBA as surrogate compounds for PAHs in this schools. Based on incremental lifetime cancer risk (ILCingestion, ILCRinhalation, ILCRdermal) and total lifetime cancer risk (TLCR)) calculations, the order of cancer risk was: urban schools > suburban schools > residential schools. Both ingestion and dermal contact are major contributors to cancer risk. Among PAHs, DBA, BaP, BbF, benzo(a)anthracene (BaA), benzo(k)fluoranthene (BkF), and IND have the highest ILCR values at all schools. LCR and TLCR values at all schools were lower than 10-6, indicating virtual safety. DBA, BaP and BbF were the predominant contributors to cancer effects in all schools.

Source apportionment and toxicity assessment of PM2.5-bound PAHs in a typical iron-steel industry city in northeast China by PMF-ILCR

This study was designed to evaluate the occurrence and variation in concentrations, sources and cancer risk of PM_2.5-bound PAHs. Airborne PM_2.5-bound PAHs were sampled during a one-year campaign (2014-2015) in Anshan city, a typical iron and steel city in northeast China. A total of 374 PM_2.5 samples were collected. A source-oriented positive matrix factorization (PMF) model and PAH diagnostic ratios were used to investigate the potential sources of PAHs in the atmospheric environment of Anshan, and the lifetime cancer risk of the population associated with PAHs through inhalation exposure was assessed by a PMF-ILCR model. Concentrations of PM_2.5 and 16 PAHs ranged from 13.55 μg/m³ to 315.96 μg/m³ and 5.08 ng/m³ to 520.02 ng/m³, respectively. These values were higher in winter. PAH content from stationary sources and biomass combustion was higher than from other sources. Through the coefficient of divergence and localized PAH diagnostic ratio methods, we concluded that PM_2.5-bound PAHs in Anshan originated mainly from the following sources: biomass combustion, vehicle emissions, fugitive dust, coking dust and natural gas emissions. Based on the source-oriented PMF model, coal combustion, fugitive dust, vehicle emissions, coking dust, and biomass combustion were the main sources contributing to PM_2.5, accounting for 26.3%, 24.6%, 21.9%, 18.0%, and 6.3% of PM_2.5, respectively. According to the PMF-ILCR model results, ILCR risks estimated for adults and children were respectively 1.19 × 10^-5 and 8.55 × 10^-6 in winter, higher than in other seasons, and higher than the threshold value (10^-6). Together, vehicle emissions (diesel exhaust and gasoline exhaust), coal combustion and coking dust, contributed to over 86% of the cancer risk associated with PM_2.5-bound PAHs exposure in Anshan.

Artificial Neural Networks to Estimate the Influence of Vehicular Emission Variables on Morbidity and Mortality in the Largest Metropolis in South America

The emission of pollutants from vehicles is presented as a prime factor deteriorating air quality. Thus, seeking public policies encouraging the use and the development of more sustainable vehicles is paramount to preserve populations’ health. To better understand the health risks caused by air pollution and exclusively by mobile sources urges the question of which input variables should be considered. Therefore, this research aims to estimate the impacts on populations’ health related to road transport variables for São Paulo, Brazil, the largest metropolis in South America. We used three Artificial Neural Networks (ANN) (Multilayer Perceptron—MLP, Extreme Learning Machines—ELM, and Echo State Neural Networks—ESN) to estimate the impacts of carbon monoxide, nitrogen oxides, ozone, sulfur dioxide, and particulate matter on outcomes for respiratory diseases (morbidity—hospital admissions and mortality). We also used unusual inputs, such as road vehicles fleet, distributed and sold fuels amount, and vehicle average mileage. We also used deseasonalization and the Variable Selection Methods (VSM) (Mutual Information Filter and Wrapper). The results showed that the VSM excluded some variables, but the best performances were reached considering all of them. The ELM achieved the best overall results to morbidity, and the ESN to mortality, both using deseasonalization. Our study makes an important contribution to the following United Nations Sustainable Development Goals: 3—good health and well-being, 7—affordable and clean energy, and 11—sustainable cities and communities. These research findings will guide government about future legislations, public policies aiming to warranty and improve the health system.

Inhibited Nitric Oxide Production of Human Endothelial Nitric Oxide Synthase by Nitrated and Oxygenated Polycyclic Aromatic Hydrocarbons

Nitrated and oxygenated polycyclic aromatic hydrocarbons (NPAHs and OPAHs) from the direct atmospheric emission or the degradation of parent PAHs are increasingly recognized because of their potential health risks. Herein, we investigated the effects of four NPAHs/OPAHs (1-NNAP, 9-NANT, 9,10-AQ, and 9-FLU) and their parent PAHs (NAP, ANT, and FLU) on endothelium function with regard to endothelial nitric oxide synthase (eNOS) and endothelium-derived nitric oxide (NO) production in human umbilical vein endothelial cells. The eNOS enzymatic activity and NO production were promoted by NAP, ANT, and FLU; however, eNOS activity was dropped by 52.8, 52.1, 52.5, and 44.5%, and NO production was decreased by 31.1, 50.3, 65.0, and 35.0% after 24 h exposure to 0.01 μM 1-NNAP, 9-NANT, 9,10-AQ, and 9-FLU, respectively. The mRNA expression of eNOS and protein expression of phosphorylated eNOS (Ser1177) were increased by three PAHs but decreased by four NPAHs/OPAHs. The 100 ns molecular dynamics simulations reveal the conformational alteration in the key propionate of heme upon the binding of NPAHs/OPAHs. Our findings provide the first in silico and in vitro evidence for the potential endothelial dysfunction of nitrated and oxygenated PAHs. The health risk implications of NPAHs/OPAHs and corresponding parent PAHs warrant further research.

Quantitation of phenanthrene dihydrodiols in the urine of smokers and non-smokers by gas chromatography-negative ion chemical ionization-tandem mass spectrometry

Polycyclic aromatic hydrocarbons (PAH) are well-established environmental carcinogens likely to be causative agents for some human cancers. Bay-region diol epoxides are ultimate carcinogenic metabolites of multiple PAH. Dihydrodiols are the important intermediate products of this pathway and can be further oxidized to form diol epoxides. We quantified two dihydrodiol metabolites of phenanthrene (Phe), the simplest PAH with a bay-region, in the 6 h urine of smokers (N = 25) and non-smokers (N = 25) using a newly developed and validated analytical method. After hydrolysis by ß-glucuronidase and sulfatase, and solid phase extraction, the sample was silylated and analyzed by gas chromatography-negative ion chemical ionization-tandem mass spectrometry (GC-NICI-MS/MS). Levels (nmol/6h urine) of Phe-1,2-dihydrodiol (Phe-1,2-D) and Phe-3,4-dihydrodiol (Phe-3,4-D) were 2.04 ± 1.52 and 0.51 ± 0.35 , respectively, in smokers, significantly higher than those in non-smokers (1.35 ± 1.11 of Phe-1,2-D, p < 0.05; 0.27 ± 0.25 of Phe-3,4-D, p < 0.005). Cigarette smoking also influenced the regioselective metabolism of Phe, presenting as a significant difference in the urinary distribution pattern of Phe-1,2-D and Phe-3,4-D between smokers and non-smokers: the ratio Phe-3,4-D: Phe-1,2-D increased from 0.20 in non-smokers to 0.28 in smokers (p < 0.01), which can be explained by the induction of the phenanthrene metabolizing enzymes CYP1A2 and CYP1B1 by cigarette smoke. The method described here is the first example of facile quantitation of an intact human dihydrodiol metabolite of any PAH with three or more aromatic rings and will be applicable in clinical and molecular epidemiology studies of PAH metabolism and cancer susceptibility.

Size distribution of particulate polycyclic aromatic hydrocarbons in fresh combustion smoke and ambient air: A review

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous in the atmosphere and they mostly stem from the imperfect combustion of fossil fuels and biofuels. PAHs are inherently associated with homogenous fine particles or distributed to different-sized particles during the aging of air masses. PAHs carried by fine particles undergo a long-range transport to remote areas while those adsorbed on coarse particles have a shorter lifetime in ambient air. More importantly, PAHs with higher molecular weights tend to be bound with finer particles and can deeply enter the lungs, posing severe health risks to humans. Thus, the environmental fate and health effects of particulate PAHs are strongly size-dependent. This review summarizes the size distributions of particulate PAHs freshly emitted from combustion sources as well as the distribution patterns of PAHs in ambient particles. It was found that PAHs from stationary sources are primarily bound to fine particles, which are slightly larger than particles to which PAHs from mobile sources are bound. In ambient air, particulate PAHs are distributed in larger size modes than those in the combustion fume, and the particle size decreases with PAH molecular weight increasing. The relevant mechanisms and influencing factors of particle size distribution changes are illustrated in this article, which are essentially attributed to combustion and ambient temperature as well as the physical and chemical properties of PAHs. Overall, the study on the particle size distribution of PAHs will contribute for a full understanding of the origin, atmospheric behaviors and health effects of particulate PAHs.

Speciation of organic fractions does matter for aerosol source apportionment. Part 3: Combining off-line and on-line measurements

The present study proposes an advanced methodology to refine the source apportionment of organic aerosol (OA). This methodology is based on the combination of offline and online datasets in a single Positive Matrix Factorization (PMF) analysis using the multilinear engine (ME-2) algorithm and a customized time synchronization procedure. It has been applied to data from measurements conducted in the Paris region (France) during a PM pollution event in March 2015. Measurements included OA ACSM (Aerosol Chemical Speciation Monitor) mass spectra and specific primary and secondary organic molecular markers from PM₁₀ filters on their original time resolution (30 min for ACSM and 4 h for PM₁₀ filters). Comparison with the conventional PMF analysis of the ACSM OA dataset (PMF-ACSM) showed very good agreement for the discrimination between primary and secondary OA fractions with about 75% of the OA mass of secondary origin. Furthermore, the use of the combined datasets allowed the deconvolution of 3 primary OA (POA) factors and 7 secondary OA (SOA) factors. A clear identification of the source/origin of 54% of the total SOA mass could be achieved thanks to specific molecular markers. Specifically, 28% of that fraction was linked to combustion sources (biomass burning and traffic emissions). A clear identification of primary traffic OA was also obtained using the PMF-combined analysis while PMF-ACSM only gave a proxy for this OA source in the form of total hydrocarbon-like OA (HOA) mass concentrations. In addition, the primary biomass burning-related OA source was explained by two OA factors, BBOA and OPOA-like BBOA. This new approach has showed undeniable advantages over the conventional approaches by providing valuable insights into the processes involved in SOA formation and their sources. However, the origins of highly oxidized SOA could not be fully identified due to the lack of specific molecular markers for such aged SOA.

Prenatal exposure to airborne polycyclic aromatic hydrocarbons and childhood growth trajectories from age 5-14 years

There is evidence that exposures to polycyclic aromatic hydrocarbons (PAH) and fine particles in air pollution are associated with higher childhood body mass index (BMI). Birth cohort analyses of prenatal exposures to PAH and child BMI Z-scores from age 5-14 years were conducted. African-American and Hispanic children born in the Bronx or Northern Manhattan, New York (1998-2006), whose mothers underwent personal air monitoring for airborne PAH exposure during pregnancy, were followed up with measurements of height and weight at approximate ages 5, 7, 9, 10, 11, 12.5 and 13.5 years. Multivariable generalized estimating equation analyses were used to relate prenatal airborne PAH exposures to child BMI Z-scores through time. The analyses adjusted for many known risk factors for childhood obesity and included interactions terms between age and exposure tertiles and age squared and exposure tertiles. In total, 535 children had at least one height and weight measure during follow-up. The prevalence of obesity was 20.6% at age 5 and increased across follow-ups until age 11 when it was 33.0%. At age 5, BMI Z-scores were significantly greater for children in the third tertile of exposure relative to the first tertile (0.35 Z-score units, 95% CI 0.09, 0.61, p = 0.007) and were non-significantly higher for the second tertile of exposure compared to the first tertile (0.25 Z-score units, 95% CI -0.02, 0.52, P = 0.075). The trajectories of BMI Z-scores by tertiles of exposure converged as the children aged, such that by age 11 years the estimated mean BMI Z-scores associated with each tertile of exposure were not different. Prenatal exposures to airborne PAH were associated with higher childhood BMI Z-scores at a young age, but growth trajectories converged by age 11 years. Accordingly, highly exposed children spend a greater proportion of their childhood with higher BMI Z-scores.

Recovery and reactivity of polycyclic aromatic hydrocarbons collected on selected sorbent tubes and analyzed by thermal desorption-gas chromatography/mass spectrometry

This article describes the optimization of methodology for extending the measurement of volatile organic compounds (VOCs) to increasingly heavier polycyclic aromatic hydrocarbons (PAHs) with a detailed focus on recent sorbent tube technology. Although PAHs have lower volatility than compounds such as benzene, toluene, ethylbenzene and xylenes, these semi-volatile compounds can be detected in air and breath samples. For this work, PAHs were captured on sorbent tubes and subsequently analyzed using automated thermal desorption gas chromatography - mass spectrometry (ATD-GC/MS). While many different sorbent tubes are commercially available, optimization for airborne PAH sampling using sorbent tubes has not been previously considered. Herein, several commercially available sorbent tubes, including Carbograph 2 TD/1TD, Tenax TA, XRO-440, and inert-coated PAH tubes are compared to determine the relative recovery for eight PAHs commonly found in the environment. Certain types of sorbent materials were found to be better suited for PAH recovery during thermal desorption, and PAH reaction products were observed on several types of sorbent tubes, including graphitized carbon black sorbents with stainless steel tube materials. As such, selection of sorbent tube media should be carefully considered prior to embarking on a PAH study.

An Overview of the Influence of Biodiesel, Alcohols, and Various Oxygenated Additives on the Particulate Matter Emissions from Diesel Engines

Rising pollution levels resulting from vehicular emissions and the depletion of petroleum-based fuels have left mankind in pursuit of alternatives. There are stringent regulations around the world to control the particulate matter (PM) emissions from internal combustion engines. To this end, researchers have been exploring different measures to reduce PM emissions such as using modern combustion techniques, after-treatment systems such as diesel particulate filter (DPF) and gasoline particulate filter (GPF), and alternative fuels. Alternative fuels such as biodiesel (derived from edible, nonedible, and waste resources), alcohol fuels (ethanol, n-butanol, and n-pentanol), and fuel additives have been investigated over the last decade. PM characterization and toxicity analysis is still growing as researchers are developing methodologies to reduce particle emissions using various approaches such as fuel modification and after-treatment devices. To address these aspects, this review paper studies the PM characteristics, health issues, PM physical and chemical properties, and the effect of alternative fuels such as biodiesel, alcohol fuels, and oxygenated additives on PM emissions from diesel engines. In addition, the correlation between physical and chemical properties of alternate fuels and the characteristics of PM emissions is explored.

Characterization of particulate-bound polycyclic aromatic compounds (PACs) and their oxidations in heavy polluted atmosphere: A case study in urban Beijing, China during haze events

Characterizations on polycyclic aromatic compounds (PACs) during frequent haze periods have been conducted in an urban site of Beijing, China. Particulate polycyclic aromatic hydrocarbons (PAHs) and oxygenated-PAHs (OPAHs) and other carbonaceous matters were quantified. The average PM_2.5 during haze events (256.3 ± 103.7 μg/m³) were one magnitude over than that of clear periods (CRs, 24.7 ± 27.7 μg/m³).The average total quantified PAHs (ΣPAHs) and OPAHs (ΣOPAHs) during haze events were 423.9 ± 178.4 ng/m³ and 581.4 ± 299.8 ng/m³, respectively, which were approximately 10 times higher than those of 40.3 ± 68.2 ng/m³ and 54.4 ± 82.4 ng/m³ in clear days. Four-rings PAHs had the highest compositions. 1,8-Naphthalic anhydride (1,8-NA) is the most abundant OPAHs, accounted for 49.8% of ∑OPAHs, followed by 9,10-anthraquinone (9,10-AQ) (13.8%) and benzo(a)anthracene-7,12-dione (BaAQ) (8.31%). In haze events, the contents of 5- to 7-rings PAHs decreased by 2.32% compared with those of clear days, while lower molecular weight fractions of 3- and 4-rings PAHs increased. The relationships between PAHs, OPAHs and relative humidity (RH) were found to be exponential. High oxygenation rate (R₀) ratios of OPAH/PAH represents higher rates in secondary formation or degradation and gas- particle conversion for each PAH or OPAH during the wintertime. Significant positive correlation between BeP and OPAHs (r = 0.97), combined with the results of photochemical aging and negatively correlation with O₃, suggest that secondary atmospheric reactions of PAHs played an important role in the burden of OPAHs.

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.

Street Dust-Bound Polycyclic Aromatic Hydrocarbons in a Saudi Coastal City: Status, Profile, Sources, and Human Health Risk Assessment

Polycyclic aromatic hydrocarbons (PAHs) in street dust pose a serious problem threatening both the environment and human health. Street dust samples were collected from five different land use patterns (traffic areas TRA, urban area URA, residential areas REA, mixed residential commercial areas MCRA and suburban areas SUA) in Jeddah, a Saudi coastal city, and one in in Hada Al Sham, a rural area (RUA). This study aimed to investigate the status, profile, sources of PAHs and estimate their human health risk. The results revealed an average concentration of total PAHs of 3320 ng/g in street dust of Jeddah and 223 ng/g in RUA dust. PAHs with high molecular weight represented 83.38% of total PAHs in street dust of Jeddah, while the carcinogenic PAH compounds accounted 57.84%. The highest average concentration of total PAHs in street dust of Jeddah was found in TRA (4980 ng/g) and the lowest in REA (1660 ng/g). PAHs ratios indicated that the principal source of PAHs in street dust of Jeddah is pyrogenic, mainly traffic emission. Benzo(a)anthracene/chrysene (BaA/CHR) ratio suggests that PAHs in street dusts of Jeddah come mainly from emission of local sources, while PAHs in RUA might be transported from the surrounding urban areas. The estimated Incremental Lifetime Cancer Risk (ILCR) associated with exposure to PAHs in street dusts indicated that both dermal contact and ingestion pathways are major contributed to cancer risk for both children and adults. Based on BaPequivalence concentrations of total PAHs, ILCRIngestion, ILCRdermal and cancer risk values for children and adults exposed to PAHs in street dust of different areas in Jeddah were found between 10-6 and 10-4, indicating potential risk. The sequence of cancer risk was TRA > URA > MCRA > SUA > REA. Only exposure to BaP and DBA compounds had potential risk for both children and adults.

Particle-Bound Polycyclic Aromatic Hydrocarbon in the Atmosphere of Heavy Traffic Areas in Greater Cairo, Egypt: Status, Source, and Human Health Risk Assessment

Airborne particulate samples were collected from three main squares (Ramsis, El Giza, and Sphinx) representing heavy traffic areas in Greater Cairo during the period of December 2015–February 2016, and analysed for polycyclic aromatic hydrocarbon (PAHs). The maximum concentrations of particle-bound PAHs were observed at El Giza, while the minimum levels were recorded at Sphinx. The levels of particle-bound PAHs in the square areas of Greater Cairo are higher than those found in many different locations in Egypt and around the world.The distribution of individual particle-bound PAHs as well as PAH categories, depending on the ring number in Ramsis, El Giza, and Sphinx, wasquite similar. This similarity implies similar emission sources of PAHs in the three square areas, with vehicle exhaust emissions being the dominant one. Benzo[b]fluoranthene (BbF), benzo[ghi]perylene (BGP), and indeno[1,2,3-cd]pyrene(IND) were the most abundant PAH compounds. Diagnostic concentration ratios of PAH compounds in the three square locations suggest that both petrogenic and pyrogenic sources emit these compounds. Moreover, they originate mainly from traffic emissions in the study areas. Based on the calculated benzo[a]pyrene equivalent (BaPeq) for the individual particle-bound PAH compounds, health risks associated with the inhalation of these compounds were assessed. Total carcinogenic activity (TCA) for all measured PAHs represented 20.03% (El Giza), 20.40% (Ramsis), and 20.60% (Sphinx) of the total PAH concentrations. Benzo[a]pyrene (BaP) and dibenz[a,h]anthracene (DBA) were the highest contributors to the total health risks; these accounted for 42.72% and 38.50% (El Giza), 41.79% and 39.17% (Ramsis), and 42.92% and 37.78% (Sphinx) of the TCA of all PAH compounds, respectively. These results indicate the importance of BaP and DBA as surrogate compounds for PAHs in the atmosphere of square areas of Greater Cairo.

Effects of Four Prototype Gasoline Particle Filters (GPFs) on Nanoparticle and Genotoxic PAH Emissions of a Gasoline Direct Injection (GDI) Vehicle

The fast replacement of traditional gasoline port-fuel injection technology with gasoline direct-injection (GDI) vehicles is expected to have a substantial impact on urban air quality. Herein we report on effects of four prototype gasoline particle filters (GPFs) on exhausts of a 1.6 L Euro-5 GDI vehicle. Two noncoated and two filters with catalytic coatings were investigated. These filters, on average, lowered PN emissions 4-7-fold to 4.0-6.8 × 10¹¹ particles/km. Genotoxic PAHs were lowered 2-5-fold too with GPF-1-3, with GPF-1 having the highest efficiency, 79% and resulting in 45 ng toxic equivalent concentration (TEQ)/km. Thus, particle filtration efficiencies and reduction of the genotoxic potentials are correlated. GPF-4 showing the poorest particle filtration efficiency (66-78%) also released exhausts with highest genotoxic potential of 240-530 ng TEQ/km. We recently reported particle-number (PN) emissions of four generations of GDI vehicles (Euro-3 to Euro-6) which released, on average, 2.5 × 10¹² ± 1.8 × 10¹² particles/km exceeding the current European limit of 6.0 × 10¹¹ particle/km. Thus, the implementation of filters to GDI vehicles requires best-available technology (BAT) with PN efficiencies >98% and catalytic activity, to avoid store-and-release of genotoxic PAHs. In-series applications of BAT-filters to GDI vehicles can lower genotoxic PAHs and soot nanoparticles.

Speciation of organic fractions does matter for aerosol source apportionment. Part 2: Intensive short-term campaign in the Paris area (France)

The present study aimed at performing PM₁₀ source apportionment, using positive matrix factorization (PMF), based on filter samples collected every 4h at a sub-urban station in the Paris region (France) during a PM pollution event in March 2015 (PM₁₀>50μgm^-3 for several consecutive days). The PMF model allowed to deconvolve 11 source factors. The use of specific primary and secondary organic molecular markers favoured the determination of common sources such as biomass burning and primary traffic emissions, as well as 2 specific biogenic SOA (marine+isoprene) and 3 anthropogenic SOA (nitro-PAHs+oxy-PAHs+phenolic compounds oxidation) factors. This study is probably the first one to report the use of methylnitrocatechol isomers as well as 1-nitropyrene to apportion secondary OA linked to biomass burning emissions and primary traffic emissions, respectively. Secondary organic carbon (SOC) fractions were found to account for 47% of the total OC. The use of organic molecular markers allowed the identification of 41% of the total SOC composed of anthropogenic SOA (namely, oxy-PAHs, nitro-PAHs and phenolic compounds oxidation, representing 15%, 9%, 11% of the total OC, respectively) and biogenic SOA (marine+isoprene) (6% in total). Results obtained also showed that 35% of the total SOC originated from anthropogenic sources and especially PAH SOA (oxy-PAHs+nitro-PAHs), accounting for 24% of the total SOC, highlighting its significant contribution in urban influenced environments. Anthropogenic SOA related to nitro-PAHs and phenolic compounds exhibited a clear diurnal pattern with high concentrations during the night indicating the prominent role of night-time chemistry but with different chemical processes involved.

Chlorine levels and species in fine and size resolved atmospheric particles by X-ray absorption near-edge structure spectroscopy analysis in Beijing, China

An understanding of the species of chlorine is crucial in the metropolis-Beijing, which is suffering serious haze pollution with high frequency. Particulate Matters (PMs) with five different sizes were collected in Beijing from July 2009 to March 2016, and characterized non-destructively by X-ray absorption near edge structure spectroscopy. PM_<0.2, PM_0.2-0.5 and PM_>2.5 contributed for the major PMs mass in spring and summer, PM_0.5-1.0 and PM_1.0-2.5 contributed for the major PMs mass in autumn and winter. The concentrations of the three chlorine species were in the order of inorganic chlorine (Cl_inorg) > aliphatic chlorine (Cl_ali) > aromatic chlorine (Cl_aro), indicating that Cl_inorg constituted the primary chlorine fraction and less toxic Cl_ali constituted the primary total organic chlorine (Cl_ali + Cl_aro, abbreviated as Cl_org) in the PMs in Beijing. In addition, these three chlorine species exhibited identical seasonal variation in PM_2.5: winter > autumn > spring > summer. Wet precipitation is an important factor to result in the lower mass concentrations of these three chlorine species in summer. The temporal variations of both size resolved PM mass concentrations and chlorine species concentrations suggested that the air pollution prevention and control in Beijing has just won initial success.

Comparison of Airway Responses Induced in a Mouse Model by the Gas and Particulate Fractions of Gasoline Direct Injection Engine Exhaust

Diesel exhaust has been associated with asthma, but its response to other engine emissions is not clear. The increasing prevalence of vehicles with gasoline direct injection (GDI) engines motivated this study, and the objective was to evaluate pulmonary responses induced by acute exposure to GDI engine exhaust in an allergic asthma murine model. Mice were sensitized with an allergen to induce airway hyperresponsiveness or treated with saline (non-allergic group). Animals were challenged for 2-h to exhaust from a laboratory GDI engine operated at conditions equivalent to a highway cruise. Exhaust was filtered to assess responses induced by the particulate and gas fractions. Short-term exposure to particulate matter from GDI engine exhaust induced upregulation of genes related to polycyclic aromatic hydrocarbon (PAH) metabolism (Cyp1b1) and inflammation (TNFα) in the lungs of non-allergic mice. High molecular weight PAHs dominated the particulate fraction of the exhaust, and this response was therefore likely attributable to the presence of these PAHs. The particle fraction of GDI engine exhaust further contributed to enhanced methacholine responsiveness in the central and peripheral tissues in animals with airway hyperresponsiveness. As GDI engines gain prevalence in the vehicle fleet, understanding the health impacts of their emissions becomes increasingly important.

Physicochemical Characterization of Exhaust Particulates from Gasoline and Diesel Engines by Solid-Phase Micro Extraction Sampling and Combined Raman Microspectroscopic/Fast Gas-Chromotography Mass Spectrometry Analysis

Ambient Particulate Matter (PM) has been shown to be associated with cardiopulmonary diseases and lung cancer. Several groups of investigators have shown that the size of the airborne particles and their surface area determine the potential to elicit inflammatory injury and other mechanisms of adverse cellular effects. Because traffic is an important source of PM, it seems obvious that physicochemical characterization of vehicles exhaust emission has an important impact on both quantitative and qualitative aspects of ambient PM. In the present study the exhaust emissions of 8 vehicles of different categories were analyzed to attempt to differentiate them. For such purpose the particulate was collected on SPME fibers exposed to the exhaust emission for 150 s. The particulate was first characterized by micro-Raman spectroscopy and then subjected to Fast Gas Chromatography-Mass Spectrometry analyses for the chemical identification of the Polycyclic Aromatic Hydrocarbons (PAHs) compounds, the organic fraction of particulate matter in air pollution with a major role in the toxicity, notably via its effects on inflammation. Both the particle count and the PAHs compositional data were assembled to be interpreted by Principal Components Analysis. This multivariate analysis grouped the data according mainly to the naphthalene amount, as well as the volume concentration of the particles smaller than 0.5 μm, suggesting that the different exhaust emissions could be easily differentiated. With this new methodology, future research should aim at establishing a mechanism of formation during internal engine combustion processes in order to obtain a clearer picture of the inflammatory and carcinogenic mechanisms of PM in the lungs.

Chemical characterization and toxicity assessment of fine particulate matters emitted from the combustion of petrol and diesel fuels

Fuel consumption is one of the major contributors to air pollution worldwide. Plenty of studies have demonstrated that the diesel and petrol exhaust fine particulate matters (FPMs) are associated with increases of various diseases. However, the influences of different fuel types and their chemical components on toxicity have been less investigated. In this study, four kinds of fuels that widely used in China were burned in a laboratory simulation, and the FPMs were collected and analyzed. Transmission electron microscopy showed that black carbon was mainly soot with a dendritic morphology. For light diesel oil, marine heavy diesel oil, 93 octane petrol and 97 octane petrol diesel oil, the emission factors of FPMs were 3.05±0.29, 3.21±0.54, 2.36±0.33, and 2.28±0.25g/kg fuel, respectively. And the emission factors for the "16 US EPA" PAHs of FPM were 0.45±0.20, 0.80±0.22, 1.00±0.20, and 1.05±0.19mg/g FPMs, respectively. Fe is the most abundant metal in these FPMs, and the emission factors of FPMs were 2.58±1.70, 4.45±0.11, 8.18±0.58, and 9.24±0.17mg/g FPMs, respectively. We ranked the cytotoxicity of the FPMs emission from fuels combustion: marine heavy diesel oil>97 octane petrol>93 octane petrol>light diesel oil, and the genotoxicity of FPMs emission from fuels combustion: marine heavy diesel oil>light diesel oil>93 octane petrol>97 octane petrol. Significant correlations were found between PAH concentrations and reactive oxygen species (ROS) generation. Our results demonstrated that fuels exhaust FPMs have strong association with ROS activity, cytotoxicity and genotoxicity. These results indicated that fuels exhaust FPMs pose a potentially serious health, and emphasized the importance of assessing the health risks posed by the particulate pollutants in vehicle exhausts.

Biomarker Sensitivity to Vehicle Exhaust in Experimentally Exposed European Starlings

The effects of vehicle-related emissions on health has been a long-standing question in human health sciences; however, the toxicology of chronic exposure to environmentally relevant concentrations of these complex mixtures has not been characterized in wild birds. Adult European starlings (Sturnus vulgaris) were exposed to vehicle emissions, with combined benzene, toluene, ethylbenzene, and xylenes (BTEX) concentrations totaling 13.3 μg/m³ over 20 days of exposure for 5 h per day. Exposed birds had significantly lower cell-mediated immunity (measured using phytohaemagglutinin skin test, p < 0.0001), thyroxine (T4, p = 0.042), and glutathione (GSH, p = 0.034) concentrations than control birds. There was no difference in body condition, antibody response to vaccination, triiodothyronine (T3), hepatic biotransformation (7-ethoxyresorufin-O-deethylase activity), or oxidative stress (thiobarbituric acid-reactive substances and ratios of reduced to oxidized GSH) or organ masses between exposed and control birds. This study supports findings of previous studies examining wild birds exposed to these air contaminants and raises concern that environmentally relevant concentrations of common urban volatile pollutants may have measurable effects on health.

Do 16 Polycyclic Aromatic Hydrocarbons Represent PAH Air Toxicity?

Estimation of carcinogenic potency based on analysis of 16 polycyclic aromatic hydrocarbons (PAHs) ranked by U.S. Environmental Protection Agency (EPA) is the most popular approach within scientific and environmental air quality management communities. The majority of PAH monitoring projects have been focused on particle-bound PAHs, ignoring the contribution of gas-phase PAHs to the toxicity of PAH mixtures in air samples. In this study, we analyzed the results of 13 projects in which 88 PAHs in both gas and particle phases were collected from different sources (biomass burning, mining operation, and vehicle emissions), as well as in urban air. The aim was to investigate whether 16 particle-bound U.S. EPA priority PAHs adequately represented health risks of inhalation exposure to atmospheric PAH mixtures. PAH concentrations were converted to benzo(a)pyrene-equivalent (BaPeq) toxicity using the toxic equivalency factor (TEF) approach. TEFs of PAH compounds for which such data is not available were estimated using TEFs of close isomers. Total BaPeq toxicities (∑88BaPeq) of gas- and particle-phase PAHs were compared with BaPeq toxicities calculated for the 16 particle-phase EPA PAH (∑16EPABaPeq). The results showed that 16 EPA particle-bound PAHs underrepresented the carcinogenic potency on average by 85.6% relative to the total (gas and particle) BaPeq toxicity of 88 PAHs. Gas-phase PAHs, like methylnaphthalenes, may contribute up to 30% of ∑88BaPeq. Accounting for other individual non-EPA PAHs (i.e., benzo(e)pyrene) and gas-phase PAHs (i.e., naphthalene, 1- and 2-methylnaphthalene) will make the risk assessment of PAH-containing air samples significantly more accurate.

Source Apportionment of PM10-Bound Polycyclic Aromatic Hydrocarbons by Positive Matrix Factorization in Córdoba City, Argentina

The composition and concentration of polycyclic aromatic hydrocarbons (PAHs) adsorbed on particles smaller than 10 microns (PM₁₀) were analyzed in an urban area during a 2-year period from August 2011 to August 2013. Diagnostic ratios (DR) and positive matrix factorization (PMF) were employed to assess emission sources. To discount weather influence, a multiple linear regression model was generated and also a photodecomposition index was calculated for each sample. Despite the fact that mean PM₁₀ levels showed a similar pattern all around the year, majority of PAHs showed higher concentrations during the cold than the warm period, indicating a strong seasonal variation. A 38% of PAHs variation could be explained by meteorological variables, with wind speed, wind direction, and dew point being the significant regressor variables in the model. The source apportionment of PAHs was performed using PMF although they are photosensitive compounds. The sampling period was separated in warm and cold seasons according to a photodecomposition index and cold period was used. Also, DR were calculated. DR as well as PMF analysis suggested that both gasoline and diesel vehicular emissions are the main PAHs emission sources in this urban area.

Seasonal contributions to size-resolved n-alkanes (C8-C40) in the Shanghai atmosphere from regional anthropogenic activities and terrestrial plant waxes

Size-resolved aerosol samples from the Shanghai atmosphere were analyzed for normal alkanes (n-alkanes, C₈-C₄₀) by comprehensive two-dimensional gas chromatography-flame ionization detection and gas chromatography-triple quadruple mass spectroscopy to study their size distribution and contributions from potential regional sources based on a one-year (2012-2013) sampling campaign. The n-alkane concentrations ranged from 62.3 to 398.5ngm^-3, with an annual average of 227.6ngm^-3. Particle-associated n-alkanes exhibited a bimodal distribution with one peak in the accumulation-mode size range and the other in the coarse-mode size range. As the carbon number increased, the peak in the accumulation mode intensified and the peak in the coarse mode weakened, in accordance with variation of their corresponding volatilities. Source indices (carbon preference index, average chain length, odd-even carbon number preference, unresolved to resolved n-alkanes ratio, and plant wax n-alkanes ratio) indicated that the n-alkane source profile shifted from an anthropogenic-dominated pattern in winter and spring to a terrestrial plant wax-influenced pattern in summer and autumn. Further trajectory cluster analysis and potential source contribution function modeling showed that anthropogenic activities were mainly in the North China Plain and East China and that terrestrial plant waxes originated in Anhui, Zhejiang, and Jiangxi Provinces. The results of our study provide useful information for evaluating the influence of anthropogenic and biogenic activities on the atmospheric transport of important secondary organic aerosol precursors to megacities in East Asia.

Ambient PM2.5-bound polycyclic aromatic hydrocarbons (PAHs) in Changhua County, central Taiwan: Seasonal variation, source apportionment and cancer risk assessment

This study investigates PM_2.5-bound PAHs for rural sites (Dacheng and Fangyuan) positioned close to heavy air-polluting industries in Changhua County, central Taiwan. A total of 113 PM_2.5 samples with 22 PAHs collected from 2014 to 2015 were analyzed, and Positive Matrix Factorization (PMF) and diagnostic ratios of PAHs were applied to quantify potential PAH sources. The influences of local and regional sources were also explored using the conditional probability function (CPF) and potential source contribution function (PSCF) with PMF-modeled results, respectively. Annual mean concentrations of total PAHs were 2.91 ± 1.34 and 3.04 ± 1.40 ng/m³ for Dacheng and Fangyuan, respectively, and their corresponding BaP_eq were measured at 0.534 ± 0.255 and 0.563 ± 0.273 ng/m³ in concentration. Seasonal variations with higher PAHs found for the winter than for the spring and summer were observed for both sites. The lifetime excess cancer risk (ECR) from inhalation exposure to PAHs was recorded as 4.7 × 10^-5 overall. Potential sources of PM_2.5-bound PAHs include unburned petroleum and traffic emissions (42%), steel industry and coal combustion (31%), and petroleum and oil burning (27%), and unburned petroleum and traffic emission could contribute the highest ECR (2.4 × 10^-5). The CPF results show that directional apportionment patterns were consistent with the actual locations of local PAH sources. The PSCF results indicate that mainly northeastern regions of China have contributed elevated PM_2.5-bound PAHs from long-range transports.

Biochemical and physiological effects from exhaust emissions. A review of the relevant literature

Exhaust emissions are to date ranked among the most frequent causes of premature deaths worldwide. The combustion of fuels such as diesel, gasoline, and bio-blends provokes a series of pathophysiological responses in exposed subjects, which are associated with biochemical and immunological triggering. It is critical to understand these mechanisms, which are directly related to the levels of aerosol, liquid and gaseous components in fuel exhaust (e.g. nanoparticles, particulate matter, volatile compounds), so to cast attention on their toxicity and gradually minimize their use. This review reports findings in the recent literature concerning the biochemical and cellular pathways triggered during intoxication by exhaust emissions, and links these findings to pathophysiological responses such as inflammation and vasoconstriction. This study provides critical in vitro and in vivo data for the reduction of emissions in urban centers, with an emphasis on the prevention of exposure of groups such as children, the elderly, and other affected groups, and shows how the exposure to exhaust emissions induces mechanisms of pathogenesis related to cardiopulmonary pathologies and long-term diseases such as asthma, allergies, and cancer. This review summarizes the cellular and physiological responses of humans to exhaust emissions in a comprehensive fashion, and is important for legislative developments in fuel politics.