Gasoline Exhaust Emissions Research Articles

Chemical characterization, source identification and potential health effects of PM2.5-bound non-polar organic compounds over a COALESCE network site - Bhopal, India

Year-long (2019) measurements of carbonaceous aerosols were performed at Bhopal, a regionally representative site as a part of the COALESCE (Carbonaceous Aerosol Emissions, Source apportionment and Climate Impacts) campaign. Aerosol-associated non-polar organic compounds (NPOCs) were analysed using thermal desorption (TD) Gas chromatography/Mass spectrometry (TD-GC/MS). The annual average of the total organic carbon (OC), elemental carbon (EC), and analysed PAHs (Polycyclic Aromatic Hydrocarbons), and n-alkanes were, 9.74 ± 9.47 μg m−3, 2.13 ± 3.12 μg m−3, 10.43 ± 5.49 ng m−3, and 114.93 ± 49.24 ng m−3, respectively. PAHs diagnostic ratios suggested emissions from petroleum, grass, wood, and coal combustion. Combustion derived PAHs (CombPAHs) accounted for 72.5 % of the total measured PAHs. During wintertime, based on Pyr/BaP ratio (∼0.6), gasoline exhaust emissions were higher compared to diesel exhaust emissions. The weak correlations between PAHs and meteorological parameters suggested that variations in PAH levels are primarily driven by alterations in emission sources. Total PAHs were correlated moderately with BrC (r2 = 0.60). The estimated lifetime lung cancer risk (LLCR) values on exposure to 16 USEPA priority PAHs (5 × 10−5) demonstrated that PAH levels in this region pose moderate health risks. Given observations from only campaign mode short-term measurements of NPOCs over India, this work provides a more comprehensive understanding of the concentrations, seasonal variations, and sources of n-alkanes and health risk associated with particle bound PAHs over the data-poor central Indian region.

Toxicological effects of fresh and aged gasoline exhaust particles in Hong Kong

Exhaust emissions from gasoline vehicles are one of the major contributors to aerosol particles observed in urban areas. It is well-known that these tiny particles are associated with air pollution, climate forcing, and adverse health effects. However, their toxicity and bioreactivity after atmospheric ageing are less constrained. The aim of the present study was to investigate the chemical and toxicological properties of fresh and aged particulate matter samples derived from gasoline exhaust emissions. Chemical analyses showed that both fresh and aged PM samples were rich in organic carbon, and the dominating chemical species were n-alkane and polycyclic aromatic hydrocarbons. Comparisons between fresh and aged samples revealed that the latter contained larger amounts of oxygenated compounds. In most cases, the bioreactivity induced by the aged PM samples was significantly higher than that induced by the fresh samples. Moderate to weak correlations were identified between chemical species and the levels of biomarkers in the fresh and aged PM samples. The results of the stepwise regression analysis suggested that n-alkane and alkenoic acid were major contributors to the increase in lactate dehydrogenase (LDH) levels in the fresh samples, while polycyclic aromatic hydrocarbons (PAHs) and monocarboxylic acid were the main factors responsible for such increase in the aged samples.

Source identification of exhaust and non-exhaust traffic emissions through the elemental carbon fractions and Positive Matrix Factorization method

Our study implies the importance of exhaust and non-exhaust emissions in a highway road tunnel, which is crucial to assess their impacts on air quality, human health, climate and developing functional methods for controlling. The total suspended particulates (TSP) and road dust (RD) samples were collected by PUF samplers and manually sweeping, respectively. Campaigns were performed in the summer and winter of 2014 in a highway road tunnel in Bolu, Turkey. Chemical analyses were presented to characterize the contents of organic carbon (OC) fractions (OC1,2,3,4), elemental carbon (EC) fractions (EC1,2,3,4,5,6), polycyclic aromatic hydrocarbons (PAHs) and metals (Al, Ba, Ca, Cu, Mg, Mn, Pb, Sr, Cr and Fe) in the collected TSP and RD samples. Positive matrix factorization (PMF) and orthogonal (Deming) regression analysis were applied to find out the exhaust and non-exhaust vehicle emissions of metal and carbonaceous species in the tunnel. The results showed that the identified source profiles included resuspended road dust (43%), non-exhaust emissions (37%), diesel exhaust emissions (13%), and gasoline exhaust emissions (7%). The relationship between emission markers of metal species and EC carbon fractions was supported by correlation studies. Among these EC fractions, EC4 and EC2 were the most abundant fractions in aerosol and RD samples, respectively and so they highly represented the diesel and non-exhaust emissions. Besides, the EC1 fraction was the indicator of gasoline-fueled emissions. Lower EC1 and higher soot-EC contribution obtained in tunnel aerosol (AS) samples showed the dominance of diesel-fueled vehicles in the tunnel. The data represented herein would help to identify the characteristic of vehicle emissions.

Characteristics and Source Apportionment of Volatile Organic Compounds (VOCs) in the Automobile Industrial Park of Shanghai

Volatile organic compounds (VOCs) are important precursors of ozone and fine particulate matter, and have attracted more and more research attention. There are few long-term observational studies of VOCs in automobile industry parks. From January 1 to December 31,2019, 79 kinds of VOCs were quantitatively detected by on-line gas chromatograph in an automobile industrial park in Shanghai. The composition, seasonal variation, and daily variation of VOCs were analyzed. The chemical reactivity of the atmosphere was estimated using the maximum incremental reactivity (MIR) and·OH radical loss rate. The sources of VOCs were analyzed using specific pollutant ratios and factor analysis. The results showed that the total VOCs concentration was 26.53×10-9, with alkanes, alkenes, aromatics, halo hydrocarbon, and alkynes accounting for 50.2%, 9.8%, 22.4%, 10.8%, and 6.8%, respectively. There was an obviously seasonal variation in VOCs concentrations, with the maximum occurring in winter and the minimum in summer. Ozone formation potential (OFP) was 73.2×10-9, of which alkanes accounted for 14.7%, alkenes 35.9%, and aromatics 45.2%. The·OH radical loss rate was 165.3 s-1, of which alkenes accounted for 30.4% and aromatics 48.9%. The components with the highest contributions to chemical reaction activity were m/p-xylene, ethylene, propylene, toluene, and o-xylene. By estimating toluene/benzene ratios (T/B) and ethane/acetylene ratios (E/E), the air mass at the observation site was fresh, site was close to the pollution source. The main sources of VOCs were gasoline exhaust emissions (19.4%), solvent use (30.8%), combustion processes (11.0%), diesel use (8.9%), and liquefied petroleum gas use (4.5%).

Variations in Levels and Sources of Atmospheric VOCs during the Continuous Haze and Non-Haze Episodes in the Urban Area of Beijing: A Case Study in Spring of 2019

To better evaluate the variations in concentration characteristics and source contributions of atmospheric volatile organic compounds (VOCs) during continuous haze days and non-haze days, hourly observations of atmospheric VOCs were conducted using a continuous on-line GC-FID (Airmo VOC GC-866) monitoring system during 1–15 March 2019, in urban areas of Beijing, China. The results showed that the total VOC concentrations during haze days and non-haze days were 59.13 ± 31.08 μg/m3 and 16.91 ± 7.19 μg/m3, respectively. However, the average O3 concentrations during the two haze days were lower than those of non-haze days due to the extremely low concentrations at night instead of the reported lower photochemical reaction in daytime. The ratio of OH radical concentration during haze and non-haze days indicating that the rate of photochemical reaction during haze days was higher than those of non-haze days from 13:00–19:00. The stable air conditions and the local diesel emission at night were the main reasons for the decreased O3 concentrations during haze days. Six major sources were identified by positive matrix factorization (PMF), namely, diesel exhaust, combustion, gasoline evaporation, solvent usage, gasoline exhaust, and the petrochemical industry, contributing 9.93%, 25.29%, 3.90%, 16.88%, 35.59% and 8.41%, respectively, during the whole observation period. The contributions of diesel exhaust and the petrochemical industry emissions decreased from 26.14% and 6.43% during non-haze days to 13.70% and 2.57%, respectively, during haze days. These reductions were mainly ascribed to the emergency measures that the government implemented during haze days. In contrast, the contributions of gasoline exhaust increased from 34.92% during non-haze days to 48.77% during haze days. The ratio of specific VOC species and PMF both showed that the contributions of gasoline exhaust emission increased during haze days. The backward trajectories, potential source contribution function (PSCF) and concentration weighted trajectory (CWT) showed that the air mass of VOCs during haze days was mainly affected by the short-distance transportation from the southwestern of Hebei province. However, the air mass of VOCs during non-haze days was mainly affected by the long-distance transportation from the northwest.

Microstructural Characterization of Particulate Matter from Gasoline-Fuelled Vehicle Emissions

Exhaust emissions from vehicle traffic refers to the particles released into the air due to combustion of fuels, additives and wear of engine parts in the system during vehicle use. These emissions occur depending on the type of vehicle, type of fuel, combustion process and environmental conditions. In this study, microstructure and chemical characterization of particulate matter (PM) released from gasoline-fuelled vehicles were examined using electron microscopy techniques. As a result, much solid soot, metalloids, heavy metals, ash, sulphates, phosphates, minerals, volatile organic and inorganic pollutants were found to be present in gasoline exhaust emission. These toxic structures still pose a danger to environmental safety and human health.
 Aim: In study, microstructure characterization of emissions released from gasoline-fuelled vehicles exhaust were investigated using electron microscopy techniques. Study design: SEM, EDS, XRD and FTIR electron microscopy techniques were used for characterization.
 Place and Duration of Study: Material Characterization Laboratory of Karamanoğlu Mehmetbey University, Scientific and Technological Research Application and Research Center, between Junuary 2020 and July 2020.
 Results: The vehicles still continue to spread toxic pollutants.
 Conclusions: The chemical structure of PM contains 20 elements including C, F, N, Na, O, Mg, Br, Si, Hg, S, P, Pb, Ca, Cr, Mn, Fe, Ni, Co, Cu, Zn. There are pollutant functional groups such as OH, CO, SO in the structure. Hydrocarbons, metalloids, heavy metals, different minerals, phosphates, sulfates, many volatile organic and inorganic compounds pollute the air in PM structure. These toxic pollutants harm the environment and human health.

Source apportionment of PM2.5 at two Seattle chemical speciation sites

ABSTRACT Positive Matrix Factorization analysis of PM2.5 chemical speciation data collected from 2015–2017 at Washington State Department of Ecology’s urban NCore (Beacon Hill) and near-road (10th and Weller) sites found similar PM2.5 sources at both sites. Identified factors were associated with gasoline exhaust, diesel exhaust, aged and fresh sea salt, crustal, nitrate-rich, sulfur-rich, unidentified urban, zinc-rich, residual fuel oil, and wood smoke. Factors associated with vehicle emissions were the highest contributing sources at both sites. Gasoline exhaust emissions comprised 26% and 21% of identified sources at Beacon Hill and 10th and Weller, respectively. Diesel exhaust emissions comprised 29% of identified sources at 10th and Weller but only 3% of identified sources at Beacon Hill. Correlation of the diesel exhaust factor with measured concentrations of black carbon and nitrogen oxides at 10th and Weller suggests a method to predict PM2.5 from diesel exhaust without a full chemical speciation analysis. While most PM2.5 sources exhibit minimal change over time, primary PM2.5 from gasoline emissions is increasing on average 0.18 µg m−3 per year in Seattle. Implications This study utilizes Positive Matrix Factorization to determine PM2.5 sources from chemical speciation measurements at two urban Seattle sites from 2015-2017. The paper reports PM2.5 source trends, and extends previous source apportionment analyses in Seattle to the present day. The study also quantifies diesel PM2.5 at a near-road site, and describes a predictive model that allows estimation of the contribution of diesel PM2.5 to the total measured PM2.5 at near-road sites across the country without a full chemical speciation analysis.

VOC tracers from aircraft activities at Beirut Rafic Hariri International Airport

This is the first study to assess the speciation of 48 VOCs from around 100 commercial aircraft under real operation, as close as possible to aircraft engines during the various modes of the landing/takeoff (LTO) cycles to identify special aircraft fingerprints and markers. Also, Jet A-1 kerosene vapor, gasoline exhaust, and the ambient airport concentrations were assessed. Air samples were taken at Beirut Rafic Hariri International Airport inside adsorbent tubes using a portable automatic remote sampler and analyzed using gas chromatographic techniques (GC-MS and GC-FID). Results showed that heavy alkanes (C8-C14, mainly n-nonane and n-decane), which contributed to about 51–64% of the total mass of heavy VOCs emitted by aircraft, and heavy aldehydes (nonanal and decanal) – although to a lesser amount – can be considered as potential tracers for aircraft emissions due to both their exclusive presence in aircraft-related emissions and their absence from gasoline exhaust emissions. On the other hand, the total concentration of heavy alkanes in the airport's ambient air was 47% of the total mass of heavy VOCs measured. No aircraft tracer was identified among the light VOCs (≤C7); however, results showed that emissions of light VOCs decrease as the engine power increases. Also, auxiliary power unit (APU) emissions were identified to be of the same order of magnitude as main engine emissions. This study opens the door for future studies aiming at evaluating the impact of airport activities on air quality and human health within or away from the airport vicinity.

Source-specific lung cancer risk assessment of ambient PM2.5-bound polycyclic aromatic hydrocarbons (PAHs) in central Tehran

In this study, source-specific cancer risk characterization of ambient PM2.5-bound polycyclic aromatic hydrocarbons (PAHs) was performed in central Tehran. The positive matrix factorization (PMF) model was applied for source apportionment of PAHs in the area from May 2012 through May 2013. The PMF runs were carried out using chemically analyzed PAHs mass concentrations. Five factors were identified as the major sources of airborne PAHs in central Tehran, including petrogenic sources and petroleum residue, natural gas and biomass burning, industrial emissions, diesel exhaust emissions, and gasoline exhaust emissions, with approximately similar contributions of around 20% to total PAHs concentration from each factor. Results of the PMF source apportionment (i.e., PAHs factor profiles and contributions) were then used to calculate the source-specific lung cancer risks for outdoor and lifetime exposure, using the benzo[α]pyrene (BaP) equivalent method. Our risk assessment analysis indicated that the lung cancer risk associated with each specific source is within the range of 10−6–10−5, posing cancer risks exceeding the United States Environmental Protection Agency's (USEPA) guideline safety values (10−6). Furthermore, the epidemiological lung cancer risk for lifetime exposure to total ambient PAHs was found to be (2.8 ± 0.78) × 10−5. Diesel exhaust and industrial emissions were the two sources with major contributions to the overall cancer risk, contributing respectively to 39% and 27% of the total risk associated with exposure to ambient PAHs. Results from this study provide an estimate of the cancer risk caused by exposure to ambient PAHs in highly crowded areas in central Tehran, and can be used as a guide for the adoption of effective air quality policies in order to reduce the human exposure to these harmful organic species.

Gasoline particle filter reduces oxidative DNA damage in bronchial epithelial cells after whole gasoline exhaust exposure in vitro

A substantial amount of traffic-related particle emissions is released by gasoline cars, since most diesel cars are now equipped with particle filters that reduce particle emissions. Little is known about adverse health effects of gasoline particles, and particularly, whether a gasoline particle filter (GPF) influences the toxicity of gasoline exhaust emissions. We drove a dynamic test cycle with a gasoline car and studied the effect of a GPF on exhaust composition and airway toxicity. We exposed human bronchial epithelial cells (ECs) for 6 hours, and compared results with and without GPF. Two hours later, primary human natural killer cells (NKs) were added to ECs to form cocultures, while some ECs were grown as monocultures. The following day, cells were analyzed for cytotoxicity, cell surface receptor expression, intracellular markers, oxidative DNA damage, gene expression, and oxidative stress. The particle amount was significantly reduced due to GPF application. While most biological endpoints did not differ, oxidative DNA damage was significantly reduced in EC monocultures exposed to GPF compared to reference exhaust. Our findings indicate that a GPF has beneficial effects on exhaust composition and airway toxicity. Further studies are needed to assess long-term effects, also in other cell types of the lung.

Spatial and seasonal variations, sources, air-soil exchange, and carcinogenic risk assessment for PAHs and PCBs in air and soil of Kutahya, Turkey, the province of thermal power plants.

Atmospheric and concurrent soil samples were collected during winter and summer of 2014 at 41 sites in Kutahya, Turkey to investigate spatial and seasonal variations, sources, air-soil exchange, and associated carcinogenic risks of polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs). The highest atmospheric and soil concentrations were observed near power plants and residential areas, and the wintertime concentrations were generally higher than ones measured in summer. Spatial distribution of measured ambient concentrations and results of the factor analysis showed that the major contributing PAH sources in Kutahya region were the coal combustion for power generation and residential heating (48.9%), and diesel and gasoline exhaust emissions (47.3%) while the major PCB sources were the coal (thermal power plants and residential heating) and wood combustion (residential heating) (45.4%), and evaporative emissions from previously used technical PCB mixtures (34.7%). Results of fugacity fraction calculations indicated that the soil and atmosphere were not in equilibrium for most of the PAHs (88.0% in winter, 87.4% in summer) and PCBs (76.8% in winter, 83.8% in summer). For PAHs, deposition to the soil was the dominant mechanism in winter while in summer volatilization was equally important. For PCBs, volatilization dominated in summer while deposition was higher in winter. Cancer risks associated with inhalation and accidental soil ingestion of soil were also estimated. Generally, the estimated carcinogenic risks were below the acceptable risk level of 10-6. The percentage of the population exceeding the acceptable risk level ranged from <1% to 16%, except, 32% of the inhalation risk levels due to PAH exposure in winter at urban/industrial sites were >10-6.

Effect of ambient temperature on species lumping for total organic gases in gasoline exhaust emissions

Volatile organic compound (VOCs) emissions from sources often need to be compressed or “lumped” into species classes for use in emissions inventories intended for air quality modeling. This needs to be done to ensure computational efficiency. The lumped profiles are usually reported for one value of ambient temperature. However, temperature-specific detailed profiles have been constructed in the recent past - the current study investigates how the lumping of species from those profiles into different atmospheric chemistry mechanisms is affected by temperature, considering three temperatures (−18 °C, −7 °C and 24 °C). The mechanisms considered differed on the assumptions used for lumping: CB05 (carbon bond type), SAPRC (ozone formation potential) and RACM2 (molecular surrogate and reactivity weighting). In this space, four sub-mechanisms for SAPRC were considered. Scaling factors were developed for each lumped model species and mechanism in terms of moles of lumped species per unit mass. Species which showed a direct one-to-one mapping (SAPRC/RACM2) reported scaling factors that were unchanged across mechanisms. However, CB05 showed different trends since one compound often is mapped onto multiple model species, out of which the paraffinic double bond (PAR) is predominant. Temperature-dependent parameterizations for emission factors pertaining to each lumped species class and mechanism were developed as part of the study. Here, the same kind of model species showed varying lumping parameters across the different mechanisms. These differences could be attributed to differing approaches in lumping. The scaling factors and temperature-dependent parameterizations could be used to update emissions inventories such as MOVES or SMOKE for use in chemical transport modeling.

Polycyclic aromatic hydrocarbons and their nitrated derivatives associated with PM10 from Kraków city during heating season

Polycyclic Aromatic Hydrocarbons (PAHs), their nitro-derivatives (NPAHs) and hundreds of other organic compounds are present in ambient air in gas and particulate form. PAHs and NPAHs originate from diesel and gasoline exhaust emission and other combustion sources. NPAHs are also formed through the nitration of parent PAHs in the atmosphere. Concentrations of PAHs and NPAHs in the particulate matter fraction PM10 collected in the centre of Krakow (27.01.2014 – 17.02.2014) were investigated. The thirteen PAHs and four NPAHs: fluorene, phenanthrene, anthracene, fluoranthene, pyrene, benzo[a]anthracene, benzo[a]pyrene, chrysene, benzo[b]fluoranthene, benzo[k]fluoranthene, indeno[1,2,3-c,d]pyrene, benzo[g,h,i]perylene, dibenz[a,h]anthracene, 2-nitrofluorene, 9-nitroanthracene, 3-nitrofluoranthene and 1-nitropyrene were extracted from particulate matter and analysed applying the GC/MS technique. Depending on the compounds the relative recoveries ranged from 72 to 94%. The concentrations of PM10 in the study period ranged between 23.5 and 153.8 μg·m-3. The average concentrations of PAHs and NPAHs ranged from 26.6 to 276.4 ng·m-3 and from 0.6 to 9.1 ng·m-3, respectively. The highest concentrations were observed for benzo[a]pyrene, benzo[a]anthracene, pyrene and fluoranthene. The average concentration of benzo[a]pyrene (BaP), which is a marker for the particle-bound atmospheric PAHs, was 9.5 ng·m-3. The concentrations of 3-nitrofluoranthene and 1-nitropyrene were below the quantification limits of the method (< MQL).

Source apportionment of polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) in ambient air of an industrial region in Turkey

Source apportionment is generally applied to a time series of data collected at a single site. However, in a complex airshed containing several different sources, it may be helpful to collect samples from multiple sites to ensure that some of them have low contributions from specific sources, thus the boundaries can be properly defined. Ambient air polycyclic aromatic hydrocarbon (PAH) and polychlorinated biphenyls (PCB) samples (n = 160) were collected at 40 sites during four seasons (summer, fall, winter, and spring) between July 2009 and April 2010 in the heavily industrialized Aliaga region in Turkey to investigate their spatial, seasonal variations and to identify possible PAH and PCB sources. The newest version of EPA PMF (V5.0) having the capability of handling multiple site data was used for source apportionment. Five PAH sources were identified as biomass and coal combustion, iron–steel production, unburned crude oil and petroleum products, and diesel and gasoline exhaust emissions with contributions of 40, 27, 27, 3, and 3%, respectively. The sources of PCBs were identified as iron–steel production (consisting of steel-making and ship breaking activities), coal and wood combustion, and evaporative emissions from technical PCB mixtures with contributions of 57, 31, and 12%, respectively.

Measuring long chain alkanes in diesel engine exhaust by thermal desorption PTR-MS

Abstract. A method using thermal desorption sampling and analysis by proton transfer reaction mass spectrometry (PTR-MS) to measure long chain alkanes (C12–C18) and other larger organics associated with diesel engine exhaust emissions is described. Long chain alkanes undergo dissociative proton transfer reactions forming a series of fragment ions with formula CnH2n+1. The PTR-MS is insensitive to n-alkanes less than C8 but displays an increasing sensitivity for larger alkanes. Fragment ion distribution and sensitivity is a function of drift conditions. At 80 Td the most abundant ion fragments from C10 to C16 n-alkanes were m/z 57, 71 and 85. The mass spectrum of gasoline and diesel fuel at 80 Td displayed ion group patterns that can be related to known fuel constituents, such as alkanes, alkylbenzenes and cycloalkanes, and other compound groups that are inferred from molecular weight distributions such as dihydronapthalenes and naphthenic monoaromatics. It is shown that thermal desorption sampling of gasoline and diesel engine exhausts at 80 Td allows for discrimination against volatile organic compounds, allowing for quantification of long chain alkanes from the abundance of CnH2n+1 fragment ions. The total abundance of long chain alkanes in diesel engine exhaust was measured to be similar to the total abundance of C1–C4 alkylbenzene compounds. The abundance patterns of compounds determined by thermal desorption sampling may allow for emission profiles to be developed to better quantify the relative contributions of diesel and gasoline exhaust emissions on organic compounds concentrations in urban air.

INTEROCC case–control study: lack of association between glioma tumors and occupational exposure to selected combustion products, dusts and other chemical agents

BackgroundThe aim was to investigate possible associations between glioma (an aggressive type of brain cancer) and occupational exposure to selected agents: combustion products (diesel and gasoline exhaust emissions, benzo(a)pyrene), dusts (animal dust, asbestos, crystalline silica, wood dust) and some other chemical agents (formaldehyde, oil mist, sulphur dioxide).MethodsThe INTEROCC study included cases diagnosed with glioma during 2000–2004 in sub-regions of seven countries. Population controls, selected from various sampling frames in different centers, were frequency or individually matched to cases by sex, age and center. Face-to-face interviews with the subject or a proxy respondent were conducted by trained interviewers. Detailed information was collected on socio-economic and lifestyle characteristics, medical history and work history. Occupational exposure to the 10 selected agents was assessed by a job exposure matrix (JEM) which provides estimates of the probability and level of exposure for different occupations. Using a 25% probability of exposure in a given occupation in the JEM as the threshold for considering a worker exposed, the lifetime prevalence of exposure varied from about 1% to about 15% for the different agents. Associations between glioma and each of the 10 agents were estimated by conditional logistic regression, and using three separate exposure indices: i) ever vs. never; ii) lifetime cumulative exposure; iii) total duration of exposure.ResultsThe study sample consisted of 1,800 glioma cases and 5,160 controls. Most odds ratio estimates were close to the null value. None of the ten agents displayed a significantly increased odds ratio nor any indication of dose–response relationships with cumulative exposure or with duration of exposure.ConclusionThus, there was no evidence that these exposures influence risk of glioma.

Gasoline Exhaust Emissions Induce Vascular Remodeling Pathways Involved in Atherosclerosis

Epidemiological evidence indicates that environmental air pollutants are positively associated with the development of chronic vascular disease; however, the mechanisms involved have not been fully elucidated. In the present study we examined molecular pathways associated with chronic vascular disease in atherosclerosis-prone apolipoprotein E-deficient (ApoE(-/-)) mice, including markers of vascular remodeling and oxidative stress, in response to exposure to the ubiquitous environmental pollutant, gasoline engine emissions. ApoE(-/-) mice, on a high-fat diet, were exposed by inhalation to either filtered air; 8, 40, or 60 mug/m(3) particulate matter whole exhaust; or filtered exhaust with gases matching the 60-mug/m(3) concentration, for 7 weeks. Aortas and plasma were collected and assayed for changes in histochemical markers, real-time reverse transcriptase-polymerase chain reaction, and indicators of oxidative damage. Inhalational exposure to gasoline engine emissions resulted in increased aortic mRNA expression of matrix metalloproteinase-3 (MMP-3), MMP-7, and MMP-9, tissue inhibitor of metalloproteinases-2, endothelin-1 and heme oxygenase-1 in ApoE(-/-) mice; increased aortic MMP-9 protein levels were confirmed through immunohistochemistry. Elevated reactive oxygen species were also observed in arteries from exposed animals, despite absence of plasma markers. Similar findings were also observed in the aortas of ApoE(-/-) mice exposed to particle-filtered atmosphere, implicating the gaseous components of the whole exhaust in mediating the expression of markers associated with the vasculopathy. These findings demonstrate that exposure to gasoline engine emissions results in the transcriptional upregulation of factors associated with vascular remodeling, as well as increased markers of vascular oxidative stress, which may contribute to the progression of atherosclerosis and reduced stability of vulnerable plaques.

Recent Advances in Investigations of Toxicity of Automotive Exhaust

The influence of auto exhaust on man's health is difficult to gauge considering the intricacy of human environmental urban stresses and particularly of other air polluting (industrial, domestic) emissions. Epidemiological surveys made in road tunnel employees and in traffic officers have not demonstrated specific effects and have often been complicated by cigarette smoking as a factor. Long-term animal experiments run mostly on small rodents give evidence of little effect of the pathological actions of dilutions such as those encountered in high polluted cities. However the acute toxicity of gasoline exhaust emission is well known and mostly due to carbon monoxide. Considering the different types of cycles and operating conditions of vehicles (gasoline and diesel), auto exhaust gases constitute no more a chemical entity than they show, a definite toxicity. A great number of substances that they contain (nitrogen oxides, aldehydes, antiknock additives, heavy metals, possible catalysts are highly toxic as shown by in vivo and in vitro (mutagenic) tests. Interactions of the components are for the moment ignored or poorly understood. Besides, the evolution of the physicochemical properties and natures of the auto exhaust emission in the gaseous biotope of man under determined conditions of ultraviolet irradiation, temperature, and hygrometry provoke the formation of secondary products such as oxidants and ozone. Several experiments show clearly that irradiation increases the toxicity of auto exhaust significantly. For these reasons, geographical, meteorological, and chronological (circadian and seasonal) factors should be taken into consideration, especially with regard to emission standards.

Recent advances in investigations of toxicity of automotive exhaust.

The influence of auto exhaust on man's health is difficult to gauge considering the intricacy of human environmental urban stresses and particularly of other air polluting (industrial, domestic) emissions. Epidemiological surveys made in road tunnel employees and in traffic officers have not demonstrated specific effects and have often been complicated by cigarette smoking as a factor. Long-term animal experiments run mostly on small rodents give evidence of little effect of the pathological actions of dilutions such as those encountered in high polluted cities. However the acute toxicity of gasoline exhaust emission is well known and mostly due to carbon monoxide. Considering the different types of cycles and operating conditions of vehicles (gasoline and diesel), auto exhaust gases constitute no more a chemical entity than they show, a definite toxicity. A great number of substances that they contain (nitrogen oxides, aldehydes, antiknock additives, heavy metals, possible catalysts are highly toxic as shown by in vivo and in vitro (mutagenic) tests. Interactions of the components are for the moment ignored or poorly understood. Besides, the evolution of the physicochemical properties and natures of the auto exhaust emission in the gaseous biotope of man under determined conditions of ultraviolet irradiation, temperature, and hygrometry provoke the formation of secondary products such as oxidants and ozone. Several experiments show clearly that irradiation increases the toxicity of auto exhaust significantly. For these reasons, geographical, meteorological, and chronological (circadian and seasonal) factors should be taken into consideration, especially with regard to emission standards.