Size-segregated emissions and metal content of vehicle-emitted particles as a function of mileage: Implications to population exposure

Numerical study on temporal and spatial distribution of particulate matter under multi-vehicle working conditions

The high growth in the use of underground diesel vehicles has led to a large number of exhaust pollutants, especially particulate matter (PM), which is a serious threat to the lives and health of underground personnel. In this paper, based on numerical simulations and field measurements, the temporal and spatial distribution of PM in the exhaust of two vehicles and the impact on the health of underground personnel was analyzed. The results showed that in both conditions, the airflow velocity between two vehicles showed a zonal distribution, and there was an airflow vortex in the chamber under the interaction of the wind. When the vehicles were running in the same direction into the wind, PM with a concentration range of 15.79-26.32 mg/m³ could reach the height of the human respiratory belt and was mainly distributed on the east side of the roadway. Therefore, underground personnel should avoid approaching the right area of the vehicle body. In addition, PM concentration around the driver position of the vehicle was still higher than the human contact limit, so the drivers of the vehicle would need personal protection. When the vehicles were running in the same direction with the wind, compared with the airflow inlet side, the amount of PM on the airflow outlet side increased more obviously with time, especially for PM with a concentration range of 21.05-31.58 mg/m³. Also, partial PM flowed into the chamber with the airflow, such that personnel should avoid being located on the downwind side of the vehicle, and personnel in the chamber should also have personal protection.

Traffic pollution tracers in the lymphatic system tissue of children-possible link to chronic tonsillitis development: pilot study

The origin of metal elements in tonsillar tissues of children patients was investigated in order to establish the link between environmental pollution and tonsilitis diagnosis. The children lived either in a polluted, industrial region (Moravian-Silesian Region, North-East Czechia) or a clean, predominantly agricultural region (South Bohemian Region, South-East Czechia). Simultaneously, the distance of the address of the patients to the closest main road was assessed. The elemental content of the present particulate matter in the tonsil samples, coming from indicated tonsillectomies, was analysed using scanning electron microscopy equipped with an X-ray microprobe. No significant association of the elemental composition and the region was found using both bivariate and multivariate methods; however, an association with the distance to the closest main road was found. The study presents a novel assessment of the tonsillar tissues and supports the link between environmental factors (traffic-related particulate pollution) and the onset of chronic, idiopathic diseases in children, which has been debated recently.

Environmental Risk Assessment of Vehicle Exhaust Particles on Aquatic Organisms of Different Trophic Levels

Vehicle emission particles (VEPs) represent a significant part of air pollution in urban areas. However, the toxicity of this category of particles in different aquatic organisms is still unexplored. This work aimed to extend the understanding of the toxicity of the vehicle exhaust particles in two species of marine diatomic microalgae, the planktonic crustacean Artemia salina, and the sea urchin Strongylocentrotus intermedius. These aquatic species were applied for the first time in the risk assessment of VEPs. Our results demonstrated that the samples obtained from diesel-powered vehicles completely prevented egg fertilization of the sea urchin S. intermedius and caused pronounced membrane depolarization in the cells of both tested microalgae species at concentrations between 10 and 100 mg/L. The sample with the highest proportion of submicron particles and the highest content of polycyclic aromatic hydrocarbons (PAHs) had the highest growth rate inhibition in both microalgae species and caused high toxicity to the crustacean. The toxicity level of the other samples varied among the species. We can conclude that metal content and the difference in the concentrations of PAHs by itself did not directly reflect the toxic level of VEPs, but the combination of both a high number of submicron particles and high PAH concentrations had the highest toxic effect on all the tested species.

Vehicle emissions-exposure alters expression of systemic and tissue-specific components of the renin-angiotensin system and promotes outcomes associated with cardiovascular disease and obesity in wild-type C57BL/6 male mice

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Vehicle emission-exposure increases systemic and adipose renin-angiotensin signaling.

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Emission-exposure promotes renal, vascular, and adipocyte AT1 receptor expression.

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Diet and emission-exposure are associated with adipocyte hypertrophy and weight gain.

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Emission-exposure promotes expression of adipokines and adipose inflammatory factors.

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High-fat diet promotes an obese adipose phenotype, exacerbated by emission-exposure.

Exposure to air pollution from traffic-generated sources is known to contribute to the etiology of inflammatory diseases, including cardiovascular disease (CVD) and obesity; however, the signaling pathways involved are still under investigation. Dysregulation of the renin-angiotensin system (RAS) can contribute to CVD and alter lipid storage and inflammation in adipose tissue. Our previous exposure studies revealed that traffic-generated emissions increase RAS signaling, further exacerbated by a high-fat diet. Thus, we investigated the hypothesis that exposure to engine emissions increases systemic and local adipocyte RAS signaling, promoting the expression of factors involved in CVD and obesity. Male C57BL/6 mice (6–8 wk old) were fed either a high-fat (HF, n = 16) or low-fat (LF, n = 16) diet, beginning 30d prior to exposures, and then exposed via inhalation to either filtered air (FA, controls) or a mixture of diesel engine + gasoline engine vehicle emissions (MVE: 100 μg PM/m³) via whole-body inhalation for 6 h/d, 7 d/wk, 30d. Endpoints were assessed via immunofluorescence and RT-qPCR. MVE-exposure promoted vascular adhesion factors (VCAM-1, ICAM-1) expression, monocyte/macrophage sequestration, and oxidative stress in the vasculature, associated with increased angiotensin II receptor type 1 (AT1) expression. In the kidney, MVE-exposure promoted the expression of renin, AT1, and AT2 receptors. In adipose tissue, both HF-diet and MVE-exposure mediated increased epididymal fat pad weight and adipocyte hypertrophy, associated with increased angiotensinogen and AT1 receptor expression; however, these outcomes were further exacerbated in the MVE + HF group. MVE-exposure also induced inflammation, monocyte chemoattractant protein (MCP)-1, and leptin, while reducing insulin receptor and glucose transporter, GLUT4, expression in adipose tissue. Our results indicate that MVE-exposure promotes systemic and local adipose RAS signaling, associated with increased expression of factors contributing to CVD and obesity, further exacerbated by HF diet consumption.

Air Pollution of Nature Reserves near Cities in Russia

Today, protected natural areas cover about 15% of the Earth's land. These areas by definition are supposed to be free of pollution; they nevertheless suffer from the effects of aerial transport of anthropogenic polluting substances. In this study, we evaluated the impact of settlements on protected natural areas to determine the optimal distance beyond which the anthropogenic influence would be minimal. For this purpose, we analyzed the particle size distribution and the content of metals in fresh snow samples collected in the Bastak Nature Reserve and the neighboring Birobidzhan city (Russian Federation). Both sites contained comparable proportions of PM₁₀ and contents of heavy metals, which points to the transportation of air pollutants from the city to the reserve. The results of the analysis were summarized and compared with the available data on other nature reserves and nearby populated localities. Based on the research data, pollutant emissions should be decreased for cities that are closer than 50 km to nature reserves. Moreover, authorities should take into consideration atmospheric factors and distance to the nearest settlement when establishing new protected natural areas.

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

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

Toxicity assessment of particulate matter emitted from different types of vehicles on marine microalgae

Air pollution caused by vehicle emissions remains a serious environmental threat in urban areas. Sedimentation of atmospheric aerosols, surface wash, drainage water, and urbane wastewater can bring vehicle particle emissions into the aquatic environment. However, the level of toxicity and mode of toxic action for this kind of particles are not fully understood. Here we explored the aquatic toxic effects of particulate matter emitted from different types of vehicles on marine microalgae Porphyridium purpureum and Heterosigma akashiwo. We used flow cytometry to evaluate growth rate inhibition, changes in the level of esterase activity, changes in membrane potential and size changes of microalgae cells under the influence of particulate matter emitted by motorcycles, cars and specialized vehicles with different types of engines and powered by different types of fuel. Both microalgae species were highly influenced by the particles emitted by diesel-powered vehicles. These particle samples had the highest impact on survival, esterase activity, and membrane potential of microalgae and caused the most significant increase in microalgae cell size compared to the particles produced by gasoline-powered vehicles. The results of the algae-bioassay strongly correlate with the data of laser granulometry analyses, which indicate that the most toxic samples had a significantly higher percentage of particles in the size range less than 1 μm. Visual observation with an optical microscope showed intensive agglomeration of the particles emitted by diesel-powered vehicles with microalgae cells. Moreover, within the scope of this research, we did not observe the direct influence of metal content in the particles to the level of their aquatic toxicity, and we can conclude that physical damage is the most probable mechanism of toxicity for vehicle emitted particles.

Human Health Risk Assessment associated with contaminants in the finest fraction of sidewalk dust collected in proximity to trafficked roads

The objective of the study was to determine concentration of metals in sidewalk dust collected in close vicinity to heavily congested roads in Poland in order to assess non-carcinogenic and carcinogenic health risk for both children and adults associated with the ingestion, dermal contact and inhalation of sidewalk dust. Results revealed that sidewalk dust from Warsaw, Krakow, Wroclaw and Opole is heavily contaminated especially with Sb, Se, Cd, Cu, Zn, Pb, considered as indicators of traffic emission. Hazardous indices determined for different exposure pathways indicated that the greatest health risk for both children and adults is associated with the ingestion of sidewalk dust. Carcinogenic risk associated with the ingestion of sidewalk dust by children, calculated for As, Cd, Ni and Pb exceeded safe level of 1 × 10^-4 in all cities except for Warsaw. Non-carcinogenic risk of ingestion for children was two orders of magnitude higher than dermal risk and four to five orders of magnitude higher than risk of inhalation. Non-carcinogenic risk associated with the ingestion of sidewalk dust by adults is comparable with dermal contact risk and five orders of magnitude higher when inhalation risk.

Morphological and chemical composition of particulate matter in buses exhaust

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Particle size distribution is divided in two groups, particles sized under 50 μm and particles within the range of 100–1000 μm.

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Soot particles are represented by amorphous carbon, while in 5% of cases structured carbon particles is found.

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According to RAMAN spectra, large particles are carbon agglomerates of irregular form.

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Samples contained metals hazardous to organisms such as Al, Cd, Cr, Cu, Fe, Mg, Ni, Pb and Zn.

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Buses running on diesel fuel are the source of emission of predominantly large particles.

This research article investigates the particulate matter originated from the exhaust emissions of 20 bus models, within the territory of Vladivostok, Russian Federation. The majority of evaluated buses (17 out of 20) had emissions of large particles with sizes greater than 400 μm, which account for more than 80% of all measured particles. The analysis of the elemental composition showed that the exhaust emissions contained Al, Cd, Cu, Fe, Mg, Ni, Pb, and Zn, with the concentration of Zn prevailing in all samples by two to three orders of magnitude higher than the concentrations of the other elements.

An assessment of the inhalation bioaccessibility of platinum group elements in road dust using a simulated lung fluid

Metal enrichment of road dust is well characterized but available data on the bioaccessibility of metals in particle size fractions relevant to human respiratory health remain limited. The study goal was to investigate the bioaccessibility of platinum group elements (PGE), which are used as catalysts in automotive exhaust converters, in the inhalable fraction of road dust. Street sweepings were provided by the City of Toronto, Canada, collected as part of its Clean Roads to Clean Air program.The particle size relevance of road dust for inhalation exposures was confirmed using a laser diffraction particle size analyzer (mean Dx(50): 9.42 μm). Total PGE were determined in both bulk and inhalable fractions using nickel sulfide (NiS) fire-assay and instrumental neutron-activation analysis (INAA). PGE lung solubility was examined for the inhalable fraction using Gamble's extraction. Sample digests were co-precipitated with Te-Sn, to pre-concentrate and isolate PGE, prior to their measurement using inductively coupled plasma mass spectrometry (ICP-MS).Total PGE concentrations were enriched in the inhalable fraction of road sweepings. Geomean concentrations in the inhalable fraction were: palladium (Pd) (152 μg/kg), platinum (Pt) (55 μg/kg), rhodium (Rh) (21 μg/kg) and iridium (Ir) (0.23 μg/kg). Osmium (Os) concentrations were below the limit of detection (LOD). Bioaccessible PGEs (n = 16) using Gamble's solution were below LOD for Ir and ruthenium (Ru). For the remainder, the geomean % bioaccessibility was highest for platinum (16%), followed by rhodium (14%) and palladium (3.4%). This study provides evidence that PGE in road dust are bioaccessible in the human lung.

Main components of PM10 in an area influenced by a cement plant in Catalonia, Spain: Seasonal and daily variations

Particulate matter (PM) composition has a key role in a wide range of health outcomes, such as asthma, chronic obstructive pulmonary disease, lung cancer, cardiovascular disease, and death, among others. Montcada i Reixac, a municipality located in the Barcelona metropolitan area (Catalonia, Spain), for its location and orography, is an interesting case- study to investigate air pollution. The area is also characterized by the presence of different industrial emission sources, including a cement factory and a large waste management plant, as well as an intense traffic. In this study, PM₁₀ levels, trace elements, ions, and carbonaceous particles were determined for a long time period (2013-2016) in this highly polluted area. PM₁₀ samples were collected during six consecutive days in two campaigns (cold and warm) per year. A number of elements (As, Ba, Be, Bi, Ca, Cd, Ce, Co, Cr, Cs, Cu, Dy, Er, Eu, Fe, Ga, Gd, Ge, Hf, Hg, Ho, K, La, Li, Hg, Mg, Mn, Mo, Nb, Nd, Ni, Pb, Pr, Rb, Sb, Sc, Se, Sm, Sn, Sr, Tb, Th, Ti, Tl, U, V, W, Y, Yb, and Zr), ions (Cl^-, SO₄^2-, NO₃^-, and NH₄⁺), and carbonaceous content (total carbon, organic plus elemental carbon, and CO₃^2-), were analysed. These data were used to identify the PM₁₀ main components: mineral matter, sea spray, secondary inorganic aerosols, organic matter plus elemental carbon, trace elements or indeterminate fraction. Although a clear seasonality (cold vs. warm periods) was found, there were no differences between working days and weekends. Obviously, the cement plant influences the surrounding environment. However, no differences in trace elements related with the cement plant activity (Al, Ca, Ni and V) between weekdays and weekends were noted. However, some traffic-related elements (i.e., Co, Cr, Mn, and Sb) showed significantly higher concentrations in weekdays.

Morphologic and chemical composition of particulate matter in motorcycle engine exhaust

Despite the fact that environmental pollution due to motorcycle exhaust gases reports a great increase, motorcycle production exhibits a great increase through the last years. Countries of Asia and Africa are reported to be the major regions where two-wheeled vehicles are a major transportation mode, with tens of millions of units sold per year. Motorcycle exhaust particles are considered to be the major contributor to environmental pollution due to their airborne dispersion, containing great amount of polycyclic aromatic hydrocarbons (PAHs). This study aims at reporting an objective analysis of the main sources of the ambient air pollution as also particle size distribution and chemical composition analysis of particulate matter originated from the exhausts of two-wheeled vehicles used in the territory of Vladivostok, Russia. Various types of two-wheeled vehicles were examined (motorcycles, ATVs, scooters and wet bikes) using different types of engine and fuel system. Experimental results showed that there was no clear relation to the particle size distribution with the engine displacement of motorcycle and the number of strokes and the fuel system. Instead, there were reported two clear assumptions. The first one is that regarding to the motorcycle brand, a few samples did not exhibit a great percentage of PM10 fraction. The second one is that more modern vehicles, that have a harmful gas afterburning system, are usually the source of an increased percentage of PM10 emitted particles. At last, it should be mentioned that the laser particle size analysis method is capable of determining the particle sizes after their agglomeration whereas the optical morphometry method allows to determine the real particle size of emissions. In conclusion, it can be pointed out that the agglomeration of particles can lead to the reduction in the toxicity of particles emissions originated from two wheeled-vehicles.

Human biomonitoring data analysis for metals in an Italian adolescents cohort: An exposome approach

The first Italian human biomonitoring survey (PROBE - PROgramme for Biomonitoring general population Exposure) considered a reference population of adolescents, aged 13-15 years, living in urban and rural areas and investigated their exposure to metals. The study was expanded up to 453 adolescents living in the same areas of Latium Region (Italy) and blood samples were analyzed for 19 metals (As, Be, Cd, Co, Cr, Hg, Ir, Mn, Mo, Ni, Pb, Pd, Pt, Rh, Sb, Sn, Tl, V, and W) by sector field inductively coupled plasma mass spectrometry. The exposure assessment was contextualized following an exposome approach that considered several determinants related to the subjects, available environmental parameters and geo-coding of residence address. To assess the influence of exposure determinants and modifiers on children biomarkers levels we used two independent methodologies. The first makes use of the so-called Environment-Wide Association Study (EWAS) methodology while the second was based on the application of a Generalized Liner Model (GLM) capturing co-exposures to pairs of key determinants. Based on our analysis, Hg and As were positively associated with dietary pathways (primarily linked to fish and to a lesser extent to milk consumption) while Cr showed a more complex interaction between co-exposure to different dietary pathways (milk and fish) coupled to proximity of residence to industrial activities. In addition to diet, socio-economic status of the mother revealed robust statistical associations with Cd, Ni and W biomonitoring levels in the respective children.

Oral application of carbon nanofibers in rats increases blood concentration of IL6 and IL10 and decreases locomotor activity

Carbon nanofibers (CNF) are versatile nanomaterials that are widely used in various fields of science and technology. As a consequence, animals as well as humans may be exposed to such compounds via different routes. We hypothesized that oral intake of CNF will lead to an inflammatory reaction and consequently induce behavioral impairments. To address this issue, rats were fed with 500mg/kgCNF for 14days and their locomotor activity, emotional status and cognition were quantified by testing the animals in an open field set-up, elevated plus maze and in the universal problem solving box which provides information about motivation and cognition. The behavioral tests were performed 3 times within 10days. At the end of the experiment, blood samples were collected and the plasma concentrations of IL-6, IL-8, IL-1β, IL-10 and IL-18 were measured. Our results demonstrated an inflammatory reaction determined by a significantly elevated IL-6 concentration. This, however, was counteracted by an even more pronounced increase in IL-10. The behavioral effects were restricted mainly to a decrease in locomotor activity which was significant in the open field test, as well as the elevated plus maze. Other parameters indicative of cognitive performance were not influenced and also the emotional status was largely unaffected. In conclusion, our results revealed that oral intake of 500mg/kgCNF induced some adverse effects, which, however, can be still partially compensated by the organism.

Environmental metal contamination and health impact assessment in two industrial regions of Romania

We investigated two Romanian industrial regions- Copşa Mică and Zlatna, to assess the current situation of soil pollution and bioaccumulation of Pb, Cd, Cu and Zn in different vegetable species and possible risks to consumers. Both total and mobile forms of the metals were determined in soil samples, and metal content in the edible parts of root vegetable samples was also assessed. The concentrations of Pb and Zn in soil were higher in Copşa Mică than in Zlatna (566mg/kg vs 271mg/kg for Pb and 1143mg/kg vs 368mg/kg for Zn)·The metal mobility in soil from Copsa Mica decreases in the order Zn>Cu>Cd>Pb (1.88mg/kg, 0.40mg/kg, 0.22mg/kg, 0.16mg/kg, respectively), while in Zlatna, the order was Cu>Zn>Pb>Cd (0.88mg/kg, 0.29mg/kg, 0.04mg/kg, 0.01mg/kg, respectively), apparently depending on metal and soil conditions. In Copsa Mica, the amount of Pb and Cd in vegetable samples exceeded the maximum permissible limits in carrots (median concentration 0.32mg/kg for Pb and Cd) and in yellow onions (median concentration 0.24mg/kg for Cd). In Zlatna region, the content of Cd exceeded the maximum limits in yellow onions (median concentration 0.11mg/kg). The amount of Pb was higher than the maximum acceptable level in carrots from the Zlatna region (median concentration 0.12mg/kg). Cu and Zn levels were within the normal range in all vegetable samples. In the Zlatna region, the transfer factors for Pb and Cd were higher in carrots (median values of 9.9 for Pb and 21.0 for Cd) compared to carrots harvested in Copsa Mica (median values of 4.0 for Pb and 2.0 for Cd). Daily intake rates of metals through local vegetable consumption exceeded the limit values established by the European Food Safety Authority for Pb (1.2 to 2.4 times) and Cd (5.5 to 9.1 times) in both regions, with potential adverse health effects for the local population. The results highlight the need for total soil remediation action before fruit and vegetables produced in these polluted areas can be safely consumed.

Development of an assay to assess genotoxicity by particulate matter extract

The current study describes a method for assessing the oxidative potential of common environmental stressors (ambient air particulate matter), using a plasmid relaxation assay where the extract caused single-strand breaks, easily visualised through electrophoresis. This assay utilises a miniscule amount (11 µg) of particulate matter (PM) extract compared to other, cell-based methods (~3,000 µg). The negative impact of air pollution on human health has been extensively recognised. Among the air pollutants, PM plays an eminent role, as reflected in the broad scientific interest. PM toxicity highly depends on its composition (metals and organic compounds), which in turn has been linked to multiple health effects (such as cardiorespiratory diseases and cancer) through multiple toxicity mechanisms; the induction of oxidative stress is considered a major mechanism among these. In this study, the PM levels, oxidative potential, cytotoxicity and genotoxicity of PM in the region of Larissa, Greece were examined using the plasmid relaxation assay. Finally, coffee extracts from different varieties, derived from both green and roasted seeds, were examined for their ability to inhibit PM-induced DNA damage. These extracts also exerted an inhibitory effect on xanthine oxidase and catalase, but had no effect against superoxide dismutase. Overall, this study highlights the importance of assays for assessing the oxidative potential of widespread environmental stressors (PM), as well as the antioxidant capacity of beverages and food items, with the highlight being the development of a plasmid relaxation assay to assess the genotoxicity caused by PM using only a miniscule amount.

Characteristics of on-road NOx emissions from Euro 6 light-duty diesel vehicles using a portable emissions measurement system

This paper presents the on-road nitrogen oxides (NO_x) emissions measurements from Euro 6 light-duty diesel vehicles using a portable emissions measurement system on the predesigned test routes in the metropolitan area of Seoul, Korea. Six diesel vehicles were tested and the NO_x emissions results were analyzed according to the driving routes, driving conditions, data analysis methods, and ambient temperatures. Total NO_x emissions for route 1, which has higher driving severity than route 2, differed by -4-60% from those for route 2. The NO_x emissions when the air conditioner (AC) was used were higher by 68% and 85%, on average, for routes 1 and 2, respectively, compared to when the AC was not used. The analytical results for NO_x emissions by the moving averaging window method were higher by 2-31% compared to the power binning method. NO_x emissions at lower ambient temperatures (0-5°C) were higher by 82-192% compared to those at higher ambient temperatures (15-20°C). This result shows that performance improvements of exhaust gas recirculation and the NO_x after-treatment system will be needed at lower ambient temperatures.

Basophil mediated pro-allergic inflammation in vehicle-emitted particles exposure

Despite of the fact that engine manufacturers develop a new technology to reduce exhaust emissions, insufficient attention given to particulate emissions. However, diesel exhaust particles are a major source of air-borne pollution, contain vast amount of polycyclic aromatic hydrocarbons (PAHs) and may have deleterious effects on the immune system, resulting in the induction and enhancement of pro-allergic processes. In the current study, vehicle emitted particles (VEP) from 2 different types of cars (diesel - D and gasoline - G) and locomotive (L) were collected. Overall, 129 four-week-old, male SPF-class Kunming mice were subcutaneously instilled with either low dose 100, 250 or high dose, 500mg/kg VEP and 15 mice were assigned as control group. The systemic toxicity was evaluated and alterations in the percentages of the CD3, CD4, CD8, CD16, CD25 expressing cells, basophils, eosinophils and neutrophils were determined. Basophil percentages were inversely associated with the PAH content of the VEPs, however basophil sensitization was more important than cell count in VEP exposure. Thus, the effects of VEP-PAHs emerge with the activation of basophils in an allergen independent fashion. Despite the increased percentage of CD4+ T cells, a sharp decrease in basophil counts at 500mg/kg of VEP indicates a decreased inhibitory effect of CD16+ monocytes on the proliferation of CD4+ T cell and suppressed polarization into a Th2 phenotype. Therefore, although the restrictions for vehicles emissions differ between countries, follow up studies and strict regulations are needed.