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Nano-TiO2 combined with fogging technology can degrade automobile exhaust near road surfaces. Preparing nano-TiO2 in the form of three-dimensional ordered macroporous titanium dioxide (3DOM TiO2) can reduce the agglomeration of nano-TiO2 and improve the degradation effect. Thus far, in the preparation process of 3DOM TiO2 using the gelatin template method, the influence of the polystyrene (PS) microsphere concentration, particle size, and optimal roasting temperature on the crystal structure of 3DOM TiO2 has not been elucidated, and the influence of construction and external environmental factors on the degradation performance of the 3DOM TiO2 fogging material (termed a fog seal layer) needs further investigation. This study investigated the impact of various materials and environmental factors on the 3DOM TiO2 fog seal layer, proposes essential parameters for its application in construction processes, and enhanced the degradation efficiency of the 3DOM TiO2 material toward exhaust emissions. First, the key preparation parameters of 3DOM TiO2 were analyzed and optimized. Second, the effects of the fogging amount, emulsified asphalt solid content, temperature, and humidity during fogging on the macroscopic degradation performance of the 3DOM TiO2 material were investigated. The results show that in the preparation of 3DOM TiO2 , the optimal particle size of the PS microsphere solution, preparation concentration, and roasting temperature are 300 nm, 5%, and 550°C, respectively. An increase in the spray amount and emulsified asphalt solid content can significantly improve the degradation efficiency of photocatalytic materials. However, the degradation efficiency increase is unnoticeable when the application amount is extremely large, and the recommended level is 0.6 kg/m2. Additionally, an increase in the emulsified asphalt solid content will aggravate construction difficulties, and the recommended level is 60%. The degradation efficiency of the 3DOM TiO2 coatings on NOx first increases and then decreases, and the optimal temperature and humidity ranges are 27.1°C–27.3°C and 36.4%–36.8%, respectively. The degradation efficiency of the 3DOM TiO2 coatings after process optimization is 20.2% and 42.9% higher than that of 3DOM TiO2 and nano-TiO2 before process optimization, respectively. [ABSTRACT FROM AUTHOR]

Purpose: The most prevalent method of carbon monoxide (CO) suicide is inhalation of vehicle exhaust (VE). However, a new method of CO suicide has recently emerged involving charcoal burning (CB) in a confined space to produce fatal CO levels. This method has been reported from countries in Asia, associated with economic instability and media reporting of high-profile celebrity cases. The current study was undertaken to analyze rates and characteristics of CB suicides in South Australia (SA) for comparison with respect to their characteristics and scene, autopsy and toxicology findings. Methods: A search was undertaken for all intentional fatal carbon monoxide poisonings in SA between 2000 and 2019. Collected variables included age, sex, cause of death, location of death, decedent histories, scene, autopsy and toxicology findings and manner of death. Statistical analyses were performed using R (version 4.2.3). Results: There was a significant decrease in VE suicides (p < 0.05) and a significant increase in CB suicides (p < 0.001) over the 20-year period. Those who used CB were found to be, on average, between 1.5 and 15.8 years younger than those who used VE (p = 0.017). The risk factors for CB suicide included psychological/psychiatric conditions and financial problems, while VE suicides were associated with a history of physical problems and contact with the legal system. External and internal autopsy findings were consistent with the literature. Conclusion: CB suicide is perceived to be widely accessible and painless and is therefore becoming a popular suicide method. Monitoring future trends will be important to determine whether intervention is required. [ABSTRACT FROM AUTHOR]

The continuous expansion of the global vehicle fleet poses a growing threat to environmental quality through heavy metal contamination. In this scenario, monitoring to safeguard public health in urban areas is necessary. Our study involved the collection of 36 street dust and 29 moss samples from roads of a Brazilian metropolis (Recife) with varying traffic intensities as follows: natural reserve (0 vehicles per day), low (< 15,000 vehicles per day), medium (15,000–30,000 vehicles per day), and high (> 30,000 vehicles per day). ICP-AES analysis was performed to determine the concentrations of nine potentially toxic metals (Ba, Cd, Cr, Cu, Mn, Ni, Pb, V, and Zn) to assess the influence of vehicular flow on urban contamination. In the street dust samples, the mean metal concentrations (mg kg−1) exhibited the following order: Ba (503.7) > Mn (303.0) > Zn (144.4) > Cu (95.3) > Cr (56.1) > Pb (34.2) > V (28.7) > Ni (11.3) > Cd (1.5). Conversely, in the moss samples, the metal concentration order was as follows (mg kg−1): Mn (63.8) > Zn (62.5) > Ba (61.0) > Cu (17.7) > Cr (8.0) > V (7.3) > Pb (7.0) > Ni (2.9) > Cd (0.3). Roads with higher traffic volumes exhibited the highest metal enrichments in moss samples for all metals and in dust samples for Cd, Cr, Mn, Ni, and V. However, dust from low-flow roads had higher enrichments for Ba, Cu, and Zn, indicating the influential role of other traffic-related factors in metal deposition. Our findings highlight traffic flow as the predominant source of pollution in urban centers, with both street dust and moss serving as sensitive indicators of metal input attributable to vehicular traffic. These indicators offer valuable insights for urban quality monitoring and pollution control efforts. [ABSTRACT FROM AUTHOR]

Nano-TiO2 combined with cement slurry can be utilized to degrade nitrogen oxides (NOx) in vehicle exhaust, making it an excellent photocatalytic material for air purification. In practice, environmental factors can significantly affect the photocatalytic performance. In this study, a vehicle exhaust test system was developed, and the test methods and evaluation criteria for the degradation test are provided. This study investigated the photocatalytic degradation of NO2 using nano-TiO2 cement slurry through laboratory tests. The effects of temperature, relative humidity, ultraviolet (UV) radiation flux, cement slurry thickness, surface dust adherence, and the number of water rinsing cycles were examined. Additionally, nano-TiO2 cement slurries were applied to an expressway toll station. The results showed that the efficiency of photocatalytic degradation was significantly influenced by temperature and UV radiation flux, while the thickness of the cement slurry had minimal impact. The photocatalytic degradation efficiency was negatively correlated to the relative humidity, when the relative humidity of the cement slurry specimens was high. This is because the excess water (H2O) competes with NO2 for adsorption. The photocatalytic performance of the samples was significantly reduced by surface dust and rain erosion, as both led to a decrease in the amount of nano-TiO2 participating in the reaction. Furthermore, the photocatalytic material has wide-ranging potential applications. The findings of this study would support the promotion of environmentally friendly roads as a strategy to combat air pollution. [ABSTRACT FROM AUTHOR]

Traffic emissions, overpopulation, and poor urban planning have degraded the environmental quality of the Greater Cairo megacity. As road dust is considered the main sink of pollutants in urban environments, thirty road dust samples from six major roads were collected. ICP-OES was used to analyze the samples in order to determine the contamination grade using the pollution indices, decipher metal sources and geochemical associations using multivariate analysis, and evaluate the ecological and human health risks. The average contents of heavy metals were arranged in decreasing order: Fe (1181.12), Zn (201.36), Pb (66.10), Ni (32.42), Cu (26.07), Cr (26.00), Co (14.78), As (2.76), and Hg (0.93) mg/kg. The spatial pattern showed that new urban communities exhibited lower contamination levels compared to unplanned old districts, especially for traffic elements (Pb, Zn, and Cu). The highest Igeo mean value was observed for Hg (3.34) followed by Zn (1.34), Pb (1.24), Ni (0.10), As (− 0.19), Co (− 0.24), Cu (− 0.73), and Cr (− 1.05). Additionally, CF values indicated very high contamination levels for Pb and Zn, whereas the highest PLI value was observed at Ramses Street. All EF values were higher than 1.5, indicating the anthropogenic enrichment of metals. RI values classified Cairo as a region with considerable ecological risk, observing that Hg was the main contributor. Correlation analysis and PCA showed that Pb and Zn originated from vehicle exhaust, Hg, Cu, and As from domestic and industrial activities, and Fe and Co from natural origin. Cr and Ni exhibited potential carcinogenic risks for children through ingestion; conversely, the non-carcinogenic risks were within safe levels. As a result, the use of clean energy is recommended to mitigate the accumulation of heavy metals in road dust and to improve the quality of life. [ABSTRACT FROM AUTHOR]

In this study, to solve the problem of reduced efficiency of NO degradation due to the agglomeration effect of TiO2 nanoparticles, nano- TiO2 was converted to a 3D-ordered microporous [three-dimensional ordered macroporous (3DOM)] structure and combined with fog seal technology, which is expected to improve the degradation performance of nano- TiO2 on NO gas in automobile exhaust. We optimized the preparation process parameters of 3D-ordered macroporous (3DOM) TiO2 and developed and designed an experimental device for exhaust-gas catalytic degradation. We further tested and analyzed the effects of emulsified asphalt type, photocatalyst type, doping amount, and 3DOM TiO2 pore size on the photocatalytic performance of 3DOM TiO2 fog seal material. The effects of 3DOM TiO2 fog seal material on road antiskid performance were evaluated herein. The results show that the optimal coating volume of the PS microsphere solution is 0.14−0.16 mL/cm2. The optimal filling time of the precursor solution is 20 min for the preparation of 3DOM TiO2 materials by the sandwich method. The degradation efficiency of 3DOM TiO2 fog seal material for the optimal pore size was 17.0%, 15.0%, and 25.1% higher than that of nano- TiO2 , respectively. The 3D-ordered pore structure reduces the agglomeration effect of nano- TiO2 Thus, the degradation efficiency is improved. With the increase of 3DOM TiO2 doping, the degradation efficiency of fog seal materials gradually increased. However, the increment of degradation efficiency decreased. The appropriate increase of 3DOM TiO2 pore size is beneficial to the catalytic effect of light. If the pore size is significantly large, the emulsified asphalt will block the pore space and reduce the contact area between 3DOM TiO2 and exhaust gas. The optimal pore size is 300 nm. The type of emulsified asphalt on 3DOM TiO2 fog seal material degradation effect is not significant. The antislip performance of the pavement coated with 3DOM TiO2 fog seal materials can meet the requirements of specifications. The photocatalyst doping amount, type, and different 3DOM TiO2 pore sizes do not significantly affect the antislip performance of the fog seal. The novel 3DOM TiO2 photocatalytic pavement material proposed in this study is of positive significance for the reduction of automobile exhaust pollution. [ABSTRACT FROM AUTHOR]

This study investigates seasonal variations of mass absorption efficiency of elemental carbon (MAE EC) and possible influencing factors in urban Guangzhou of South China. Mass concentrations of elemental carbon (EC) and organic carbon (OC) in PM 2.5 and aerosol absorption coefficient (b ap) at multi-wavelengths were simultaneously measured in four seasons of 2018–2019 at hourly resolution by a semi-continuous carbon analyzer and an aethalometer. Seasonal average mass concentrations of EC were in the range of 1.36–1.70 µgC/m3 with a lower value in summer than in the other seasons, while those of OC were in the range of 4.70–6.49 µgC/m3 with the lowest value in summer and the highest in autumn. Vehicle exhaust from local traffic was identified to be the predominant source of carbonaceous aerosols. The average aerosol absorption Ångström exponents (AAE) were lower than 1.2 in four seasons, indicating EC and b ap were closely related with vehicle exhaust. Seasonal MAE EC at 550 nm was 11.0, 8.5, 10.4 and 11.3 m2/g in spring, summer, autumn, and winter, respectively. High MAE EC was related with the high mass ratio of non-carbonaceous aerosols to EC and high ambient relative humidity. [ABSTRACT FROM AUTHOR]

Vehicle exhaust emission is an important source of atmospheric volatile organic compounds (VOCs). Understanding vehicle exhaust VOCs emission characteristics and influencing factors can provide an essential theoretical basis for their pollution control. Bench test and PEMS are the major methods to carry the exhaust pollutants emission research. This review summarizes the experimental research progress of vehicle exhaust VOCs, introduces the emission characteristics of vehicle exhaust VOCs under different test methods, and compares the emission factors and component characteristics of VOCs obtained from different studies, including fuel and vehicle types, emission standards, operating conditions, starting mode, accumulated miles driven and fuel composition of different factors on VOCs emissions. In addition, the analysis and determination of OVOCs components, vehicle driving behavior emission reduction and biomass fuel applications will be the key research directions in the future. [ABSTRACT FROM AUTHOR]

Polycyclic aromatic hydrocarbons (PAHs) are a group of toxic organic compounds from vehicle emissions. Many PAHs are carcinogenic, teratogenic, mutagenic, and immunotoxic, causing a negative impact on human health and severe damage to the environment and ecosystems. Although PAH derivatives, including nitro-polycyclic aromatic hydrocarbons (NPAHs) and oxygenated polycyclic aromatic hydrocarbons (OPAHs), are one to three orders of magnitude lower in concentration than PAH parents, some components are far more mutagenic and carcinogenic than PAH parents. The PAHs and their derivatives in motor vehicle exhaust emission are mainly caused by the incomplete combustion of fossil fuels, and their emission characteristics vary with the combustion conditions and fuel compositions. With the increasingly strict control of exhaust emission standards and the gradual popularization of electric vehicles, non-exhaust emissions have become the main contributors to traffic air pollution. Therefore, as the main source of PAHs in an urban environment, non-exhaust emissions, including brake wear, tire wear, road dust resuspension, and road wear emissions, cannot be ignored in terms of their contribution proportion. The emission characteristics of PAHs and their derivatives from vehicles are mainly affected by many factors, such as combustion conditions, road conditions, and the types of motor vehicle parts and materials. This paper collates and summarizes the existing data on vehicle exhaust and non-exhaust emissions of PAHs and their derivatives at home and abroad. In general, for exhaust emission, stricter emission standards lead to lower emission of PAHs and their derivatives; under operating modes, including cold start and acceleration, the engine combustion efficiency is reduced, leading to an increase in emission; the emission of diesel vehicles is much higher than that of gasoline vehicles; gasoline direct injection (GDI) exhibits higher PAH emissions than port fuel injection (PFI); and emissions increase with increasing vehicle mileage. At present, studies on the non-exhaust emission of PAHs and their derivatives are lacking. Existing studies find that the chemical composition of brake pads, braking conditions, tire materials, and pavement conditions affect non-exhaust emissions, but these findings have a high degree of uncertainty and need further research. This paper is intended to analyze the emission characteristics of PAHs and their derivatives from motor vehicles under different influence factors to provide a scientific basis for developing emission control technology and formulating policy standards.

In the present work, volatile organic compounds (VOCs) from vehicle exhaust and cooking fumes were investigated via simulation experiments, which covered engine emissions produced during gasoline direct injection (GDI) using two kinds of fuels and cooking emissions produced by preparing three domestic dishes. The distinct characteristics of VOCs emitted during the two processes were identified. Alkanes (73% mass fraction on average) and aromatics (15% on average) dominated the vehicle VOCs, while oxygenated VOCs (49%) and alkanes (29%) dominated the cooking VOCs. Isopentane (22%) was the most abundant species among the vehicle VOCs. N-hexanal (20%) dominated the cooking VOCs. The n-hexanal-to-n-pentanal ratio (3.68 ± 0.64) was utilized to identify cooking VOCs in ambient air. The ozone formation potential produced by cooking VOCs was from 1.39 to 1.93 times higher than that produced by vehicle VOCs, which indicates the significant potential contribution of cooking VOCs to atmospheric ozone. With the equivalent photochemical age increasing from 0 h to 72 h, the secondary organic aerosol formation by vehicle VOCs was from 3% to 38% higher than that of cooking VOCs. Controlling cooking emissions can reduce SOA pollution in a short time due to its higher SOA formation rate than that of vehicle VOCs within the first 30 h. However, after 30 h of oxidation, the amount of SOAs formed by vehicle exhaust emissions exceeded the amount of SOAs produced by cooking activities, implying that reducing vehicle emissions will benefit particle pollution for a longer time. Our results highlight the importance of VOCs produced by cooking fumes, which has not been given much attention before. Further, our study suggested that more research on semi-volatile organic compounds produced by cooking emissions should be conducted in the future. [ABSTRACT FROM AUTHOR]

Organic acids are abundant aerosol components that impact the hygroscopicity and multiphase processes of particulate matter, yet their changing compositions and sources are poorly understood. In this study, filter‐based PM2.5 samples were collected concurrently at three sites (urban, rural, and coastal) during the summer and winter of 2018 in the megacity Guangzhou, south China, to determine organic acids including C9–C32 fatty acids, C4–C10 dicarboxylic acids, and aromatic acids. On average, the total concentrations of the speciated organic acids were higher in winter than in summer, and were the highest at the urban site. Compared to observations at the same sites in winter 2009, average concentrations of organic acids in winter 2018 increased by 35.0%, 66.0%, and −3.2% at the urban, rural and coastal sites, while their fractions in organic matter (OM) increased by approximately 261.5%, 266.7%, and 61.1%, and their fractions in PM2.5 increased by approximately 318.2%, 308.7%, and 221.1%, respectively. Source apportionment of organic acids revealed that cooking emission and vehicle exhaust were the major sources at the urban site, plant wax and vehicle exhaust were the two largest sources at the rural site with substantial contributions from biomass burning in winter, while vehicle exhaust and ship emission were the two major sources at the coastal site. Less contributions from secondary production were retrieved in winter 2018 than in winter 2009, and the enrichment of organic acids in PM2.5 or OM was attributed to their elevated primary emissions from vehicles and ships, cooking, and plant wax. Plain Language Summary: Organic acids are an abundant class of organic components in fine particles (PM2.5). Although proposed to be important components of PM2.5, the changing composition and sources of organic acids are poorly understood. Here, we investigated PM2.5‐bound organic acids at three sites (urban, rural, and coastal) in a megacity in south China during summer and winter 2018 and found that the speciated organic acids were higher in winter than in summer, and were the highest at the urban site. Moreover, we found that primary emissions were major sources of organic acids, including cooking emission and vehicle exhaust at the urban site, plant wax, vehicle exhaust and biomass burning at the rural site, vehicle exhaust and ship emission at the coastal site. Compared to our observations at the same sites in winter 2009, we found that the fractions of organic acids in PM2.5 increased times. The enrichment of organic acids in PM2.5 was attributed to their elevated primary emissions from vehicles and ships, cooking, and plant wax after nearly a decade. Our results highlight that organic acids have become more abundant components in PM2.5 after nearly a decade, controlling primary sources of organic acids is effective to reduce PM2.5 pollution. Key Points: PM2.5‐bound organic acid concentrations increased or remained unchanged at typical sites in the Pearl River Delta in 2018 than in 2009The fractions of organic acids in PM2.5 and organic matter in winter increased times in 2018 than in 2009Organic acids had more contributions by primary emissions and less by secondary production after nearly a decade [ABSTRACT FROM AUTHOR]

Seasonal variations in atmospheric ultrafine particulate matter (PM0.1) were monitored in Bangkok, Thailand, from 2016 to 2017. PM0.1-bound organic carbon (OC) and elemental carbon (EC) were collected by a cascade air sampler that can collect PM0.1 and were analyzed by a Thermal-Optical carbon analyzer following the IMPROVE-TOR protocol. The annual average PM0.1 in Bangkok was 14.5 ± 4.7 µg/m3, which is higher than in large Asian cities such as Shanghai and Hanoi. Biomass burning from neighboring areas was shown to increase the particle concentration. Apparent increases in carbon species such as OC and EC, and the OC/EC ratios in the wet and dry seasons were observed; the Char-EC/Soot-EC ratio revealed that the PM0.1 in the Bangkok atmosphere was influenced mainly by vehicle exhausts, even though the influence of biomass burning was greater during the dry season. The effective carbon ratio (ECR) shows that Bangkok's carbonaceous aerosol is light-absorbing and -scattering. The higher SOC/OC in the dry season indicates the high level of secondary sources forming smaller particles from the combustion sources in Bangkok, increasing light scattering during these periods, and contributing to climate and air quality. The findings of this work are of great importance to air pollutant control policies in urban areas. [ABSTRACT FROM AUTHOR]

Vehicle exhaust has been acknowledged as an essential factor affecting human health due to the extensive use of cars. Its main components include volatile organic compounds (VOCs) and nitrogen oxides (NOx), which can cause acute irritation and chronic diseases, and significant research on the treatment of vehicle exhaust has received increasing attention in recent decades. Recently, photocatalytic technology has been considered a practical approach for eliminating vehicle emissions. This review highlights the crucial role of photocatalytic technology in eliminating vehicle emissions using semiconductor catalysts. A particular emphasis has been placed on various photocatalytic materials, such as TiO2-based materials, Bi-based materials, and Metal–Organic Frameworks (MOFs), and their recent advances in the performance of VOC and NOx photodegradation. In addition, the applications of photocatalytic technology for the elimination of vehicle exhaust are presented (including photocatalysts combined with pavement surfaces, making photocatalysts into architectural coatings and photoreactors), which will offer a promising strategy for photocatalytic technology to remove vehicle exhaust. [ABSTRACT FROM AUTHOR]

In the efforts at controlling automobile emissions, it is important to know in what extent air pollutants from on-road vehicles could be truly reduced. In 2014 we conducted tests in a heavily trafficked tunnel in south China to characterize emissions of volatile organic compounds (VOC) from on-road vehicle fleet and compared our results with those obtained in the same tunnel in 2004. Alkanes, aromatics, and alkenes had average emission factors (EFs) of 338, 63, and 42 mg km-1 in 2014 against that of 194, 129, and 160 mg km-1 in 2004, respectively. In 2014, LPG-related propane, n-butane and i-butane were the top three non-methane hydrocarbons (NMHCs) with EFs of 184 ± 21, 53 ± 6 and 31 ± 3 mg km-1; the gasoline evaporation marker i-pentane had an average EF of 17 ± 3 mg km-1; ethylene and propene were the top two alkenes with average EFs of 16 ± 1 and 9.7 ± 0.9 mg km-1, respectively; isoprene had no direct emission from vehicles; toluene showed the highest EF of 11 ± 2 mg km-1 among the aromatics; and acetylene had an average EF of 7 ± 1 mg km-1. While EFs of total NMHCs decreased only 9% from 493 ± 120 mg km-1 in 2004 to 449 ± 40 mg km-1 in 2014, their total ozone formation potential (OFP) decreased by 57% from 2.50 × 103 mg km-1 in 2004 to 1.10 × 103 mg km-1 in 2014, and their total secondary organic aerosol formation potential (SOAFP) decreased by 50% from 50 mg km-1 in 2004 to 25 mg km-1 in 2014. The large drop in ozone and SOA formation potentials could be explained by reduced emissions of reactive alkenes and aromatics, due largely to fuel transition from gasoline/diesel to LPG for taxis/buses and upgraded vehicle emission standards.

The real‐time Benzene, Toluene, Ethylbenzene, and Xylenes (BTEX) concentrations were measured in a metropolitan city of India during January to May of 2020 and 2014‐2015‐2018 to assess the impact of emission reduction during the COVID‐19 lockdown. The total BTEX (∑BTEX) concentrations were 11.5 ± 9.0, 15.7 ± 16, 5.3 ± 5.0, 2.9 ± 2.0, and 0.93 ± 1.2 ppbv in January–May 2020, respectively. The evening rush hour peaks of BTEX during lockdown decreased by 4–5 times from the same period of years 2014‐2015‐2018. A significant decline in background concentrations suggests a regional‐scale reduction in anthropogenic emissions. The contributions of ∑TEX compounds to ∑BTEX increased from 42% to 59% in winter to 64%–75% during the lockdown under hot summer conditions. While emission reductions dominated during the lockdown period, the meteorological and photochemical factors may also have contributed. Meteorological influence on actual observed BTEX data was removed by normalizing with ventilation coefficient (VC). The actual ambient air reductions of 85%–90% and VC‐normalized reductions of 54%–88% of the BTEX concentrations during lockdown were estimated compared to those during the same period of 2014‐2015‐2018. The estimated changes using nighttime data, which take into account BTEX photooxidation removal, are ∼8% lower than the VC‐normalized estimates using all data. These significant reductions in BTEX concentrations are consistent with the change in people's movement as inferred from mobility data during the lockdown. Although enforced, the significant decline in ambient BTEX levels during lockdown was a good change for the air quality. The study suggests a need for more effective science‐based policies that consider local and regional factors. Plain Language Summary: Outbreaks of the COVID‐19 pandemic necessitated the implementation of strict lockdown in India, which drastically decreased anthropogenic emissions. The elevated levels of a group of aromatic volatile organic compounds known as benzene, toluene, ethylbenzene, and xylenes (BTEX) can adversely impact human health. The real‐time continuous measurements of ambient air BTEX concentrations were conducted in a major city of India during January–May 2020. The concentrations of all BTEX compounds declined drastically during the COVID‐19 lockdown period. We incorporated the VC in the ambient air BTEX concentrations to reduce the meteorological influences. During the lockdown, different BTEX compounds were reduced by 54%–88% compared to the same period during the normal years. In addition to reduced anthropogenic activities, the balance between photochemical processes and evaporative emissions seems to control BTEX concentration and composition during the lockdown period. Although enforced, the decrease of ambient BTEX concentrations was a good change for air quality as these compounds are primary pollutants and precursors for secondary pollutants. This is the most comprehensive study, investigating the impact of the lockdown on ambient BTEX concentrations in India. Key Points: Significant reductions in ambient benzene, toluene, ethylbenzene, and xylenes (BTEX) concentrations during COVID‐19 lockdown in a major city of IndiaMeteorology‐corrected BTEX concentrations during lockdown‐2020 decreased by 54%–88% from the same period of 2014–2015–2018The estimates accounting for the photo oxidation removal cause lesser reductions by ∼8% than ventilation coefficient‐normalized estimates [ABSTRACT FROM AUTHOR]

Purpose Vehicle exhaust emissions primarily comprise of nitrogen, oxygen, water, CO2, NO2, CO, hydrocarbons and particulate matter. While adverse effects of hydrocarbon and particulate matter on cardiovascular functions are known, the effect of pro-oxidants CO2, NO2 and CO are not clear. Methods Here, using an animal model of a simulated mixture of pro-oxidants (0.04% CO2, 0.9 ppm NO2 and 3 ppm CO with air as a base), we examined the effect of simulated vehicle exhaust exposure (SVEE) on various cardiovascular parameters. Male Sprague-Dawley rats were exposed to SVEE or ambient air (Control: CON) for 30 min/day for 2 weeks. Thereafter, systolic and diastolic blood pressure, heart rate and glomerular filtration rate were measured. Later, rats were sacrificed, blood plasma and kidneys were collected. Results The systolic and diastolic blood pressure, heart rate and glomerular filtration rate remained unchanged. Plasma corticosterone increased in SVEE rats when compared to CON group. Plasma 8-isoprostane, a systemic marker of oxidative stress, increased while total antioxidant capacity decreased in SVEE but not in CON. Kidney cortical tissue homogenates exhibited increase in superoxide, hydrogen peroxide and protein carbonylation in SVEE but not CON, all indicative of heightened oxidative stress. Renal cortical mitochondrial SOD activity was significantly reduced in SVEE than CON. Conclusion Significant decline in mitochondrial respiration and oxygen consumption was observed, in addition to low ATP, reduced ATP synthase and cytochrome C oxidase levels, as well as accelerated mitochondrial fission, and reduced fusion processes, were observed in SVEE than CON rats, all indicative of renal mitochondrial impairment.

Considering that vehicle exhaust contributes to the majority of nitrogen oxides (NOx), which is harmful to environment and climate, it is important to measure NOx concentrations in sustainable developments. This article proposes to apply spectroscopic gas sensing methods and an innovative deep learning network algorithm for obtaining high-precision NOx data. The adopted mid-infrared sensor technology is based on mid-infrared spectroscopy combined with an advanced substrate-integrated hollow waveguide (iHWG) sensing interface. Using extreme learning machine (ELM) algorithms with an exceptionally fast learning speed when dealing with big data problems next to excellent generalization abilities, a deep learning network for regressing NOx concentrations was implemented. Moreover, to further improve the regression performance the proposed deep ELM was provided with features derived from supervised learning improving its ability to address target constituents. Finally, experiments with gas mixtures containing three species relevant in exhaust emission monitoring have confirmed the utility of the developed approach. [ABSTRACT FROM AUTHOR]

Continuous measurements of a wide range of non-methane hydrocarbons (NMHC) have been performed since 2001 in Paris megacity and three French medium-sized cities (Grenoble, Marseille, and Strasbourg). After a careful verification of the data measured, the ambient concentrations are used to analyze the spatial and seasonal variability of the anthropogenic NMHC and determine the present NMHC emission ratios relative to acetylene, a useful metric to evaluate and constraint emission inventories. We show that NMHC urban composition is consistent between all cities with no industrial influence and characteristic of the urban emission mixtures, which are mostly dominated by vehicle exhaust emissions. In winter, the urban NMHC composition generally shows an enhancement in combustion-derived products (alkenes, acetylene), C2-C3 alkanes and benzene, which presumes seasonal changes in emission ratio values. Present emission ratios of NMHC relative to acetylene are determined in Paris and Strasbourg both in summer and winter. They generally compare within a factor of two except for C7-C9 aromatics in Paris. On a seasonal basis, summertime emission ratios are three times higher than wintertime ones while they stay constant for combustion derived product (alkenes) and benzene. The unburned gasoline fraction (alkanes and C7-C9 aromatics) shows the maximum difference up to a factor of seven. These findings suggest that the emission ratios reflect seasonal changes in emissions and can be a useful metric to constraint temporally resolved emission inventories at different time of the year. © 2013 Elsevier Ltd.

Continuous measurements of a wide range of non-methane hydrocarbons (NMHC) have been performed since 2001 in Paris megacity and three French medium-sized cities (Grenoble, Marseille, and Strasbourg). After a careful verification of the data measured, the ambient concentrations are used to analyze the spatial and seasonal variability of the anthropogenic NMHC and determine the present NMHC emission ratios relative to acetylene, a useful metric to evaluate and constraint emission inventories. We show that NMHC urban composition is consistent between all cities with no industrial influence and characteristic of the urban emission mixtures, which are mostly dominated by vehicle exhaust emissions. In winter, the urban NMHC composition generally shows an enhancement in combustion-derived products (alkenes, acetylene), C2-C3 alkanes and benzene, which presumes seasonal changes in emission ratio values. Present emission ratios of NMHC relative to acetylene are determined in Paris and Strasbourg both in summer and winter. They generally compare within a factor of two except for C7-C9 aromatics in Paris. On a seasonal basis, summertime emission ratios are three times higher than wintertime ones while they stay constant for combustion derived product (alkenes) and benzene. The unburned gasoline fraction (alkanes and C7-C9 aromatics) shows the maximum difference up to a factor of seven. These findings suggest that the emission ratios reflect seasonal changes in emissions and can be a useful metric to constraint temporally resolved emission inventories at different time of the year. © 2013 Elsevier Ltd.

Recently, enormous research passion has been devoted to reduce air pollution caused by vehicle emissions. Effective vehicle emission control method is to convert exhaust pollutants by placing catalyst in the exhaust pipe. However, the major stumbling block is that a large portion of emission occurs in the initial 20–30 s during the engine cold-start stage, before catalyst can reach its operating temperature. To address the challenge, herein we developed a catalyst utilizing Pd and Rh as active components, Ce-Zr solid solution as assistant, γ-Al2O3 as coating and Fe-Cr-Al as supporter. The catalyst component was optimized (atom ratio of Ce:Zr is 6:4, mass ratio of Pd:Rh is 8:2, total weight of Pd and Rh is 1.2 g/L, pore density is 700 pores/inch2) and high-frequency electrical heating technique was employed to decrease operating temperature from 400°C to 350°C and improve exhaust conversion efficiency by 78%.

Vehicle exhaust emissions primarily comprise of nitrogen, oxygen, water, CO2, NO2, CO, hydrocarbons and particulate matter. While adverse effects of hydrocarbon and particulate matter on cardiovascular functions are known, the effect of pro-oxidants CO2, NO2 and CO are not clear. Here, using an animal model of a simulated mixture of pro-oxidants (0.04% CO2, 0.9 ppm NO2 and 3 ppm CO with air as a base), we examined the effect of simulated vehicle exhaust exposure (SVEE) on various cardiovascular parameters. Male Sprague-Dawley rats were exposed to SVEE or ambient air (Control: CON) for 30 min/day for 2 weeks. Thereafter, systolic and diastolic blood pressure, heart rate and glomerular filtration rate were measured. Later, rats were sacrificed, blood plasma and kidneys were collected. The systolic and diastolic blood pressure, heart rate and glomerular filtration rate remained unchanged. Plasma corticosterone increased in SVEE rats when compared to CON group. Plasma 8-isoprostane, a systemic marker of oxidative stress, increased while total antioxidant capacity decreased in SVEE but not in CON. Kidney cortical tissue homogenates exhibited increase in superoxide, hydrogen peroxide and protein carbonylation in SVEE but not CON, all indicative of heightened oxidative stress. Renal cortical mitochondrial SOD activity was significantly reduced in SVEE than CON. Significant decline in mitochondrial respiration and oxygen consumption was observed, in addition to low ATP, reduced ATP synthase and cytochrome C oxidase levels, as well as accelerated mitochondrial fission, and reduced fusion processes, were observed in SVEE than CON rats, all indicative of renal mitochondrial impairment. [ABSTRACT FROM AUTHOR]

The atmospheric aerosol dynamics model (AADM) has been widely used in both comprehensive air quality model systems and chemical transport modeling globally. The AADM consists of Smoluchowski's coagulation equation (SCE), whose solution undergoing Brownian coagulation in the free molecular regime is a challenge because it is inconsistent with aerosols whose size distribution cannot exactly follow the lognormal size distribution. Thus, a new method for solving the SCE without assuming lognormal size distribution is proposed and developed. The underlying principle of this method is that the hybridization of the well‐established method of moments with the assumed lognormal size distribution (log MOM) and Taylor‐series expansion method of moments (TEMOM) is implemented. This method shows excellent agreement with the sectional method (SM) which is used as reference. The accuracy of these two specific models closely approaches that of the TEMOM, but overcomes the limitation of the classical log MOM. The computational time of this scheme is considerably lower than that of the SM. The new method was successfully implemented to reveal the formation and growth of secondary particles emitted from a vehicle exhaust tailpipe. It was found that the formation of new particles only occurs in the interface region of the turbulent exhaust jet (which is very close to the tailpipe exit), whereas no new particles are formed in the mixture of the exhaust jet plume and the surrounding cold air downstream. The new method is verified as an efficient and reliable numerical scheme for studying atmospheric aerosol dynamics. Key Points: A new mathematical method for solving SCE is first proposed and developedThis method shows excellent agreement with the Sectional Method which is used as referenceThe new method is verified as an efficient and reliable numerical scheme for studying atmospheric aerosol dynamics [ABSTRACT FROM AUTHOR]

In cities, the main source of air pollutants is vehicle exhaust. It has become an urgent problem for many cities to explore the law of vehicle exhaust diffusion and actively seek for improvement measures. At present, there are many researches on the simulation of vehicle exhaust diffusion, but few on the modeling of diffusion process and volume visualization analysis. This paper integrates California line source dispersion model‐4(CALINE4) model and 3DGIS to solve the problem of urban vehicle exhaust diffusion simulation and dynamic visualization. Firstly, a street‐scale framework of vehicle exhaust diffusion simulation and visualization is established, and a continuous concentration field is established to express the diffusion processing. A unified data model is used in the semantic space to integrate the data of buildings, roads, trees and dynamic diffusion process data. Secondly, a graphics processing unit ‐ based direct volume rendering method is used to visualize the dynamic diffusion data, and this algorithm is improved in real‐time gradient calculation, texture sampling and time‐based interpolation. Finally, this paper analyzes the vehicle exhaust diffusion of a road in the central business district area of Beijing. The experimental results show that the coupling application of 3DGIS and CALINE4 model can better reveal the spatial and temporal distribution characteristics of urban vehicle exhaust and concentration, which verifies the reliabless and efficiency of the proposed method. [ABSTRACT FROM AUTHOR]

Brown carbon (BrC) is a type of organic carbon with light-absorbing abilities, especially in ultraviolet (UV) radiation, which could significantly contribute to global warming. Observations have shown high BrC concentrations and absorption in China, suggesting potentially large BrC emissions. The potential contribution of fossil fuel combustion to BrC emission has been ignored in most previous studies. Here, we use GEOS-Chem to simulate BrC distribution and absorption in China, accounting for three major primary BrC sources: residential coal and biofuel combustion, vehicle exhausts, and open biomass burning. Based on the literature and related energy consumption data, we estimate the specific emission ratio of BrC versus BC, and BrC mass absorption efficiency (MAE) for each source. Combined with BC emission, total BrC emission in China is then estimated to be 3.42 Tg yr−1 in 2018, of which 71% is from residential combustion, 14% is from vehicle exhaust, and 15% is from open biomass burning. Residential combustion is the main source of surface BrC in China, accounting for 60% on average, followed by open biomass burning (23%) and vehicle exhaust emissions (17%). There is a clear seasonality in surface BrC concentrations with the maximum in winter (5.1 µg m−3), followed by spring (2.8 µg m−3), autumn (2.3 µg m−3), and summer (1.3 µg m−3). BrC AAOD at 365 nm ranges from 0.0017 to 0.060 in China, mainly dominated by residential combustion (73%), followed by open biomass burning (16%), and vehicle exhaust emissions (11%). It is also estimated that BrC accounts for 45–67% (52% on average) of total carbonaceous aerosol AAOD at 365 nm, implying an equal importance of BrC and BC regarding the absorption in UV radiation.

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. Unlabelled Image [ABSTRACT FROM AUTHOR]

Firefighters are potentially exposed to many carcinogens while at fires. There is also concern that firefighters may be at risk of exposure to carcinogens at other times, such as exposure to diesel engine exhaust (DEE) within fire halls. The study objective was to evaluate DEE levels in career fire halls in Ontario, Canada. Twelve career fire halls from six cities across the province of Ontario, Canada were recruited. In each hall, 24-hr DEE area samples were collected using NIOSH method 5040 (modified) for respirable elemental carbon in three locations (vehicle bay, dormitory, living quarters). Sampling was conducted in both the summer and winter to assess seasonal differences. Factors that may influence DEE exposures were also collected including presence of local exhaust ventilation (LEV), emergency run data, vehicle bay design, and age of fire apparatus. LEV was assessed using a thermo-anemometer during both campaigns. Of the 69 samples collected, 16% had detectable elemental carbon concentrations, where all but one was taken within the vehicle bay (range: <0.5 µg/m3–2.7 µg/m3). The data indicates vehicle bay exposures may be higher in halls with LEV units, those that respond to more emergencies, have a back-in vehicle bay design compared to drive-through design, and during the summer season. Three samples (4.3%) exceeded the 1.03 µg/m3 proposed Dutch occupational exposure limit; however, the estimated exceedance fraction of the underlying vehicle bay exposure distribution was 17%. Eight halls had LEV units, where performance ranged from 3.6% to 85.3% (median = 54%) when compared to manufacturer recommendations. The results show that firefighters may be at an increased risk of exposure to DEE when in fire halls and that LEV units should be assessed regularly for efficiency. Although no occupational exposure limit for DEE is currently available for industrial/non-industrial workplaces in Ontario, fire departments should continue to implement DEE control strategies to reduce exposures to mitigate potential health risks. Additional exposure studies are recommended to better understand DEE exposure in fire halls. [ABSTRACT FROM AUTHOR]

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Vehicle emissions are affected by factors such as vehicle type, fuel quality, and engine repair. Therefore, mobile source profiles should be established based on a characteristic fleet for a specific region. This study characterised the chemical composition of PM 2.5 emitted from motor vehicles that are commonly used in Xi'an through dynamometer tests. The tested fleet included light duty diesel vehicles (LDDVs; eight sample sets), heavy duty diesel vehicles (HDDVs; six sample sets), light duty gasoline vehicles (LDGVs; eight sample sets), one natural gas vehicle (NGV; four sample sets) and one methanol vehicle (MV; two sample sets). Similarities and differences among the source profiles were compared and evaluated. Overall, carbon species (13.14–59.11%) were the major components of PM 2.5 for each type of vehicle, and the content of organic carbon (OC) was generally higher than that of elemental carbon (EC). Moreover, NO 3 − (18.577–220.062 mg·g−1) was the dominant water-soluble ion and the Ca2+ (2.429–17.209 mg·g−1) and Na+ (1.966–20.798 mg·g−1) contents in PM 2.5 were high. In terms of elements, the PM 2.5 emitted from various types of vehicles consisted of abundant Al (2.183–94.949 mg·g−1), Fe (0.567–12.297 mg·g−1), and Zn (0.659–5.195 mg·g−11). In addition, the PM 2.5 profiles were significantly affected by fuel type. In general, emissions from the LDGVs and NGV exhibited higher contents of OC (477.0–479.1 mg·g−1). The greatest fractions of water-soluble ions (32.94%) and total elements (11.74%) were observed in emissions from the NGV and MV, respectively. For the same type of vehicle, the OC/EC ratio was possibly dependent on the emission standards. The PM 2.5 emitted from the LDDVs with stricter emission standards exhibited higher OC/EC ratios, whereas the OC/EC ratios displayed a decreasing trend for the LDGVs under more stringent emission standards. Unlabelled Image • PM 2.5 profiles of conventional and alternative fuel vehicles were characterised. • Gasoline and natural gas vehicles emitted higher contents of OC. • The highest fraction of water-soluble ions was observed from the NGV. • The highest percentage of elements was observed from the MV. • The OC/EC ratio was impacted by the emission standards for the same type of vehicle. [ABSTRACT FROM AUTHOR]

The information about the dispersion and scavenging of traffic-related pollutants at the locations near busy expressways is very helpful to highway planners for developing better plans to reduce exposures to air pollution for people living as well as children attending schools and child care centers near roadways. The objective of the current study was to give information in the dispersion and scavenging of vehicle-derived pollutants at the region near a busy urban expressway by a combination of two different model calculations. The modified Gaussian dispersion model and the Lagrange type below-cloud scavenging model were applied to evaluate NOx dispersion and DEP (Diesel exhaust particles) wet removal, respectively. The highest NOx was marked 53.17 ppb within 20-30 meters from the target urban expressway during the heaviest traffic hours (08:00AM-09:00AM) and it was 2.8 times higher than that of really measured at a nearby ambient measuring station. The calculated DEP concentration in size-resolved raindrops showed a continuous decreasing with increasing raindrop size. Especially, a noticeable decrease was found between 0.2 mm and 1.0 mm raindrop diameter.

Abstract Recent studies have suggested that automobile pollution poses significantly more harmful health impacts than previously realized. Light-rail transit (LRT) is a major type of transportation infrastructure, but there has been little research assessing the air quality effects of LRT based on the actual air pollution data. This study aimed to assess the effects of LRT on automobile-related air emissions in Houston. Specifically, we examined the effects of LRT on key tailpipe pollutants-carbon monoxide and acetylene-as well as other traffic pollution surrogates referred to as BTEX (benzene, toluene, ethylbenzene, and xylene), measured from ambient air monitoring stations. An interrupted time series design and analysis was used to determine the impact of an intervention, where the intervention was the opening of an LRT on January 1, 2004, with two years (2002−2003) of before and two years (2004–2005) of after period data. We found that, after controlling for weather, the opening of the LRT was associated with statistically significant reductions in traffic-related air emissions. Specifically, at the exposure sites, the daily maximum carbon monoxide level was reduced roughly by 24%, and the daily level of toluene was reduced roughly by 60% (33% after accounting for the reduction at the comparison site). Our findings lend support to the air quality benefits of LRT by providing suggestive evidence of positive effects of LRT based on actual air pollution monitoring data. This study's findings also emphasize the importance of developing effective measures to assess traffic-related pollution and call for advanced data collection strategies of additional data, including traffic volume and speed data. Graphical abstract Unlabelled Image Highlights • The effect of LRT on traffic-related air pollution was assessed. • An interrupted time series design and analysis was used. • Significant reductions in traffic-related pollution were observed after LRT opening. • The data provided support for the air quality benefits of LRT. [ABSTRACT FROM AUTHOR]

Abstract The particulate matter (PM) pollution from vehicle exhaust is one of the main pollution sources in atmospheric environments. Triboelectric particular filter (TPF), coupling triboelectric effect and electrostatic absorption, can effectively controls the emission of nanoscale particulate matter in vehicle. In this work, the captured carbon collected by TPF presents regular graininess particles closed to 100 nm. It is designed as electrode material of the supercapacitor (SC) for energy storage. The SC directly fabricated by the captured carbon without any treatment process displays excellent capacitance performance, which capacitance remains stable during 100,000 continuous cycles. Furthermore, a self-powered system was integrated from triboelectric nanogenerator (TENG) and SCs, which can sustainably power an electronic watch by harvesting biomechanical energy. This work not only presents a novel method to reduce the particular nanoscale particle emission of vehicle but also provides a novel technique to reuse of the captured carbon as energy storage devices to achieve the recycling of waste and the environmental protection simultaneously. Graphical abstract fx1 Highlights • A new method to control the emission of nanoscale particles in vehicles via triboelectric particular filter (TPF) is provided，which can capture micro/nano particles relaying on a coupling effect of triboelectric effect and electrostatic absorption. • The captured carbon collected by TPF presents regular graininess particles closed to 100 nm, which is designed as electrode material of the supercapacitor (SC) for energy storage. The SC directly fabricated by the captured carbon without any treatment process displays excellent capacitance performance, which capacitance remains stable during 100,000 continuous cycles. • A self-powered system was integrated from triboelectric nanogenerator (TENG) and the fabricated SCs, which can power an electronic watch sustainably by harvesting biomechanical energy. • This work provides a novel technique to reuse of the captured carbon as energy storage material to achieve the recycling of waste and the environmental protection simultaneously. [ABSTRACT FROM AUTHOR]

Abstract The occurrence and concentrations of a wide range of organic phosphates (OPEs) in vehicle's exhaust (VPM), ambient air particulate matter (APM), and soil of various urban environments were researched. VPM comes from passenger cars, commercial vehicles, marine and bus engines emitted in New European Driving Cycle tests whereas APM was sampled in several sites of the Upper Silesia region (Poland). APM and VPM collected on filters and soil from the same locations as APM sampling sites were extracted with dichloromethane and extracts analyzed by gas chromatography-mass spectrometry. The OPEs found include aryl phosphates such as triphenyl phosphate (TPhP) and tricresyl phosphate (TCP), alkyl phosphates - triethyl phosphate (TEP), tripropyl phosphate (TPP), tributyl phosphate (TBP) and tri(butoxyethyl)phosphate (TBEP), and alkylchlorinated phosphates including tris-(2-chloroisopropyl) phosphate (TCiPP) and tris(2-chloroethyl) phosphate (TCEP). Occurrence and concentrations of these compounds in the PM investigated are highly variable. It was found that total concentrations in APM are directly related to traffic density in particular sites of the urban environment and a style of a vehicle driving. The highest emission of OPEs was found at a crossroad and city center sites where traffic is the densest and vehicles stops and starts are frequent. Village and residential areas were less exposed to OPEs emission. Since OPEs concentrations show exponential correlations to each other also human exposure to these compounds increases exponentially with increasing traffic density. High TEP and TBP level is tentatively proposed as an indicator of emission from petrol-fueled cars. Concentrations of OPEs in some soil are related to their emission to the air and resistance to degradation of a particular compound since only the most resistant TCiPP and TPhP were identified in soil extracts. Graphical abstract Image 1 Highlights • Distribution and concentrations of organic phosphates in vehicle exhausts assessed. • Organic phosphates in urban, industrial, and village air particulate matter and soil investigated. • Concentration levels of organic phosphates in the air directly related to their use in vehicle lubricants. • Low preservation of organic phosphates in soil found. Occurrence, distribution, and concentrations of organic phosphates in the ambient air of the different sites of the urban environment are related to emission from traffic sources. [ABSTRACT FROM AUTHOR]

Abstract Identifying contamination sources of environmental media and revealing their changing trends over time is useful for regional contamination control and environmental improvements. Four sediment cores (S1−S4) were collected from the Shima River to determine lead (Pb) concentrations, geochemical fractions and isotopic compositions, as well as the geochronology of core S3. The results show that Pb concentrations decreased from the upper and middle reach sites (means: 57.6, 95.9, and 97.6 mg kg−1, respectively) to the lower reach site (43.8 mg kg−1), resulting in a minimal to moderate enrichment in the sediments; enrichment increased due to anthropogenic Pb inputs at the river middle reach site since the 1990s. Sediment Pb in the geochemical fractions followed a decreasing order of reducible (47.3%) > residual (37.8%) > oxidizable (11.2%) > acid-soluble fraction (3.68%), exhibiting high mobility, further verifying the anthropogenic inputs. A descending trend in the 206Pb/207Pb ratio of the top sediments was the result of anthropogenic activities. In the present study, coal combustion, which was the major anthropogenic Pb source determined by its isotopic composition, contributed significantly (means: 18.4–60.6%) to sediment Pb based on a three end-members model. Less of a contribution (0–10.6%) was derived from vehicle exhaust. The increasing trend in the coal contribution was in accordance with that of the coal consumption in the study area. These results suggest that Pb contamination resulting from coal combustion has grown to become a major environmental issue in the study area. Graphical abstract Image 1 Highlights • 30-year pollution history of sediment Pb was reconstructed in an urbanized watershed. • EFs of Pb indicated an increasing enrichment at the middle reach site since 1993. • Mn hydro (oxides) were found to be the major sink for anthropogenic Pb. • Coal consumption contributed more significantly than vehicle exhaust to sediment Pb. Coal combustion was identified as the major anthropogenic Pb source, with a more significant contribution than that of vehicle exhaust, to the enrichment of Pb in sediments from the Shima River. [ABSTRACT FROM AUTHOR]

In this study, we implement a numerical model to predict secondary organic aerosol (SOA) formation from semi- and intermediate-volatility organic compounds emitted from in-use gasoline and diesel vehicles. The model is formulated based on the volatility basis set (VBS) approach, and it accounts for OH oxidation of unspeciated low-volatility organics, which are classified by their volatility. This model incorporates SOA formation data from smog chamber and emission measurements of vehicle exhaust in a Hybrid framework to calculate the contribution of both traditional and non-traditional SOA precursors to total SOA formation observed in photo-oxidation experiments. Emission and SOA formation data were acquired from a series of experiments conducted at the Center for Atmospheric Particle Studies, Carnegie Mellon University on different gasoline and diesel vehicles. Instead of assigning surrogate compounds, the source-specific mass yield for non-traditional SOA precursors are calculated directly from the experiments. The present performance of the model is in good agreement with its previous application to aircraft exhaust. Based on the model predictions, a set of average VBS mass yields for each class of vehicles is presented. The obtained yield matrix is able to reproduce the observed SOA concentrations in the smog chamber within the measurement uncertainty. [ABSTRACT FROM AUTHOR]

About 30% of the fuel energy is lost in combustion engines to the exhaust gas. New development of thermoelectric materials allows to partly recuperating the lost heat. New Half-Heusler materials using only low-priced elements show promising performances for heat conversion in the temperature range of a vehicle exhaust. An investigation of the installation of Half-Heusler-based thermoelectric generators at the manifold and after the exhaust after-treatment system (ATS) of 4 light duty vehicles (2 gasolines and 2 diesels) has been made. Gas temperatures at the manifold and after the ATS were simulated based on measured data. These reach 800 °C and 600 °C respectively during a typical driving cycle. During the WLTC, an average of 100 W of electricity can be generated at the manifold and 30 W after the ATS, without adding specific heat transfer enhancing devices in the exhaust pipe. The geometric dimensions of the TEGs must be adapted in order to match the optimal thermal resistance according to their location in the exhaust and the vehicle type (differing heat flows and temperatures) to recuperate an optimal amount of energy. [ABSTRACT FROM AUTHOR]

For human health benefits it is crucial to see if carcinogenic air pollutants like polycyclic aromatic hydrocarbons (PAHs) are reduced accordingly along with the control of the criteria pollutants including fine particles (PM 2.5 ). A number of studies documented that enhanced temporary emission control during the 2014 Asia-Pacific Economic Cooperation summit (APEC) in Beijing resulted in substantial drops of observed ambient PM 2.5 , as well as PAHs, in urban areas of Beijing, yet it is not clear whether PM 2.5 -bound PAHs in the rural areas were also lowered during the APEC. Here filter-based PM 2.5 samples were collected at a rural site in northeast of Beijing, and analyzed for 25 PAHs before (Oct. 27-Nov. 2, 2014), during (Nov. 3–12, 2014) and after (Nov. 13, 2014–Jan. 14, 2015) the APEC. Observed concentrations of PM 2.5, OC and EC during the APEC dropped by about 30%, however, average PM 2.5 -bound PAHs and their incremental lifetime cancer risk (ILCR), 25.65 ng/m 3 and 3.2 × 10 −4 , remained almost unchanged when compared to that of 25.48 ng/m 3 and 3.5 × 10 −4 , respectively, before the APEC. After the APEC with the start of wintertime central heating in urban Beijing on Nov. 15, 2014, average total concentration of PAHs and their ILCR highly elevated and reached 118.25 ng/m 3 and 1.5 × 10 −3 , respectively. Source apportioning by positive matrix factorization (PMF) revealed that coal combustion was the largest source that contributed 63.2% (16.1 ng/m 3 ), 78.5% (20.1 ng/m 3 ) and 56.1% (66.3 ng/m 3 ) to the total PAHs before, during and after the APEC, respectively. Uncontrolled residential coal use during the APEC was found to be the reason for unabated levels of PAHs, and the largely aggravated PAHs after the APEC was resulted from increased coal consumption for wintertime residential heating. Our results suggested reducing emission from residential coal combustion is crucial to mitigate carcinogenic PAHs in ambient air, especially in rural areas. [ABSTRACT FROM AUTHOR]

This study reports results from a tunnel experiment impact of real-world traffic-related particle and gas parent and halogenated polycyclic aromatic hydrocarbons (PAHs and HPAHs) on urban air. The traffic related emission characteristics and subsequent environmental behavior of these compounds were investigated. To understand the significance of real-world transport emissions to the urban air, traffic-related mass emissions of PAHs and HPAHs were estimated based on measured emission factors. According to our results, PAHs and HPAHs emissions via particulate phase were greater than those via gaseous phase; particles in 2.1–3.3 μm size fraction, have the major contribution to particulate PAHs and HPAHs emissions. Over all, contribution of traffic-related emission of PAHs (only ∼3% of the total PAHs emission in China) is an overstated source of PAHs pollution in China. Actually, exhaust pipe emission contributed much less than the total traffic-related emission of pollutants. [ABSTRACT FROM AUTHOR]

Gasoline vehicles are a major source of anthropogenic secondary organic aerosols (SOAs). However, current models based on known precursors fail to explain the substantial SOAs from vehicle emissions due to the inadequate understanding of the formation mechanism. To provide more information on this issue, the formation of SOAs from ozonolysis of four light-duty gasoline vehicle exhaust systems was investigated with a vacuum ultraviolet photoionization mass spectrometer (VUV-PIMS). Remarkable SOAs formation was observed and the SOAs were primarily aliphatic alkenes. PI mass spectra of the SOAs from all vehicles exhibited similar spectral patterns (a regular mass group with m/z at 98, 112, 126 …). Interestingly, most carbonyl products of aliphatic alkenes observed as major gaseous products have specific molecular weights, and the main formation pathway of SOAs can be explained well using aldol condensation reactions of these carbonyls. This is a direct observation of the aldol condensation as a dominated pathway for SOAs formation, and the first report on the composition and formation mechanism of the SOAs from the ozonolysis of gasoline vehicle exhaust is given. The study reveals that low molecular weight alkenes may play a more significant role in vehicle-induced SOAs formation than previously believed. More importantly, the PI mass spectra of SOAs from vehicles show similarities to the field aerosol sample mass spectra, suggesting the possible significance of the aldol condensation reactions in ambient aerosol formation. Since carbonyls are a major degradation product of biogenic and anthropogenic VOCs through atmospheric oxidation processes, the mechanism proposed in this study can be applied more generally to explain aerosol formation from the oxidation of atmospheric hydrocarbons. [ABSTRACT FROM AUTHOR]

• The concentration of CO in the exhaust gas drops rapidly to less than 24 ppm after 1 m of exhaust. • The area of exhaust pollution generated is mainly centered in the rear space of the vehicle, as this area is affected by the wind flow blocked by the bodywork. • The exhaust gas discharged into the roadway space will show different degrees of diffusion distribution in the three directions of XYZ axis. • Appropriate increase in wind speed is conducive to rapid dilution of exhaust pollution. As the main tool for transporting people and materials in coal mines with inclined shafts, fuel vehicles easily cause exhaust gas accumulation and significant pollution due to the special underground environment. In this paper, the problem of exhaust gas migration under the action of a special airflow field in underground confined space is studied. First, a physical model of exhaust gas migration in the confined space of an underground coal mine is established. By combining numerical simulations with field measurements, the law of exhaust gas migration of fuel vehicles under the action of an airflow field in a confined space is studied. The results show that the migration and diffusion of CO gas in exhaust gas are affected by airflow, and the concentration decreases with an increasing distance. The main irregular pollution area is concentrated within one meter of the space behind the vehicle. The pollution area of more than 24 ppm is approximately 0.124 m2, the pollution length is approximately 0.767 m, and the pollution width and height are 1.16 m and 1.83 m, respectively. In the adjustable range of the research conditions and air speed, the increase in the air speed can accelerate the dilution of CO gas, but it needs to be maintained in a reasonable air speed range. In this paper, a theoretical basis for exploring the migration and distribution of fuel vehicle exhaust pollution in confined spaces is provided. [ABSTRACT FROM AUTHOR]

Vehicle exhaust and oil fuel evaporation emit volatile organic compounds (VOCs). The differences in VOC compositions and their effects determined using different methods have not been addressed sufficiently. In this study, VOC samples are obtained from single gasoline and diesel vehicle exhausts using a portable emission measurement system, from a tunnel in Yichang City, and from gasoline and diesel evaporation at gas stations. A total of 107 VOCs are analysed. The calculated VOC source profiles (based on VOC source profiles of single-vehicle type and vehicle fleet composition in the tunnel) and the tested source profiles (from a tunnel test) are compared. The results show that gasoline burning can reduce alkenes from a mass fraction of 53.1% (for evaporation) to 3.6% (for burning), as well as increase the mass fraction of alkenes from 1.3% (for diesel evaporation) to 34.0% (for diesel burning). The calculated VOC source profiles differed from the tested VOC source profiles, with a coefficient of divergence of 0.6. Ethane, ethylene, n-undecane, and n-dodecane are used to distinguish VOCs in gasoline and diesel exhausts. Cis-2-butene, 2-methylpentane, m/p-xylene, o-xylene, and n-decane can be used to separate gasoline from diesel. The xylene/ethylbenzene ratios accurately reveal the photochemical age. Gasoline burning increases health risks associated with VOCs compared with gasoline evaporation. Furthermore, it modifies the main contributor to ozone formation potential. This study is expected to facilitate refined VOC source apportionment and studies pertaining to speciated emission inventories. [Display omitted] • VOC source profile of vehicles detected through various method are different. • VOC source profiles were different between fuel evaporation and fuel burning. • Gasoline burning led to an increase in health risk than its evaporation. [ABSTRACT FROM AUTHOR]

Background Evidence on the short-term effects of ultrafine particles (with diameter < 100 nm, UFP) on health is still inconsistent. New particles in ambient urban air are the result of direct emissions and also the formation of secondary UFP from gaseous precursors. We segregated UFP into these two components and investigated their impact on daily mortality in three Spanish cities affected by different sources of air pollution. Methods We separated the UFP using a method based on the high correlation between black carbon (BC) and particle number concentration (N). The first component accounts for aerosol constituents emitted by vehicle exhaust (N1) and the second for the photochemical new particle formation enhancements (N2). We applied city-specific Poisson regression models, adjusting for long-term trends, temperature and population dynamics. Results Mean BC levels were higher in Barcelona and Tenerife (1.8 and 1.2 μg·m − 3 , respectively) than in Huelva (0.8 μg·m − 3 ). While mean UFP concentrations were similar in the three cities, from which N1 was 40% in Barcelona, 46% in Santa Cruz de Tenerife, and 27% in Huelva. We observed an association with N1 and daily mortality in Barcelona, by increasing approximately 1.5% between lags 0 and 2, per an interquartile increase (IQR) of 3277 cm − 3 , but not with N2. A similar pattern was found in Santa Cruz de Tenerife, although none of the associations were significant. Conversely, in the industrial city of Huelva mortality was associated with N2 at lag 0, by increasing 3.9% per an IQR of 12,032·cm − 3 . Conclusion The pattern and origin of UFP determines their short-term effect on human health. BC is possibly the better parameter to evaluate the health effects of particulate vehicle exhaust emissions, although in areas influenced by domestic solid fuel combustion this should also be taken into account. [ABSTRACT FROM AUTHOR]