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

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

Determination of trace elements in the nanometer, ultrafine, fine, and coarse particulate matters in an area affected by light vehicular emissions in the city of Rio de Janeiro.

The objective of this work was to determine the trace element composition in the nanometric, ultrafine, fine, and coarse particulate matters (PM) found in the surrounding area of the UERJ Chemical Technology Applications Institute, using a MSP 120 MOUDI II cascade impactor. After acid extraction, the elements were analyzed via ICP-OES, and the results obtained were treated statistically. The average concentrations of the nanometric, ultrafine, fine, and coarse particles were 11.8, 8.2, 7.7, and 7.1 µg m-3, respectively. The total average concentration of Cd, Ni, Pb, Cr, and Fe complied with the air quality standards recommended by US EPA and WHO. When compared with other locations, the PM fractions found in this study were 1.1 to 346 times greater. Through the calculation of Pearson's correlation coefficient, a high correlation was observed between most of the trace elements studied, especially in the ultrafine, fine, and coarse fractions, which suggests that they are probably caused by the same sources of vehicular emissions. The enrichment factor was calculated to estimate the possible sources. Since Cd, Cu, Pb, and Mo are enriched by anthropic sources, they are probably influenced by vehicular emissions, in particular the wear on tires and brakes, and the burning of fossil fuel.

Preliminary Study of Ambiente Levels and Exposure to BTEX in the Rio de Janeiro Olympic Metropolitan Region, Brazil.

This study aims to determine BTEX concentrations in the Metropolitan Region of Rio de Janeiro (MRRJ, Brazil) and evaluate potential health risks of benzene and ethylbenzene exposure based on the collected data, in 2015, the year before the Rio 2016 Olympic Games. Samples were collected and analyzed following method TO-15 (U.S.EPA). Toluene was the most abundant compound in all samples (mean concentration 16.72 ± 15.70 µg m-3). The average benzene concentration in ambient air (3.44 ± 3.14 µg m-3) was slightly lower than the yearly average "upper assessment threshold", 3.5 µg m-3, established by EU Directive 2008/50/EC. The calculated cancer risk values were > 1 × 10-6 for all samples, clearly indicating a potential cancer risk and the importance of fixed measurements by the monitoring stations to assess ambient air quality in the urban areas of the MRRJ. Calculated ratios for the BTEX species indicate that these compounds are predominantly emitted from vehicular sources with a contribution from industrial sources.

Understanding high tropospheric ozone episodes in Bangu, Rio de Janeiro, Brazil.

This study investigates the potential factors that contribute to frequent high levels of ozone in Bangu, one of the most critical areas in the city of Rio de Janeiro, regarding ozone levels and air quality. Speciated non-oxygenated volatile organic compounds (VOCs) were measured using method TO-15 (US EPA). The measured concentrations and kinetic and mechanistic analysis of VOC reactivity showed that alkanes were the most important compounds. Ozone concentrations were simulated for a base case representing a day with high ozone levels. Simulated results and statistical multivariate analysis showed that the high ozone concentrations did not seem to be closely related to local emissions but rather were related to pollutant transport and low measured NOx levels and were triggered by photochemical activity. The differences between weekdays and weekends were also investigated, showing that ozone concentrations were also higher during weekends, mainly on Sunday, when the diesel heavy vehicle fleet was reduced and lower NO emissions were observed. The VOC/NOx ratios correspond to a VOC-limited process, which leads to higher ozone concentrations under low NOx conditions.

Criteria and aldehyde emissions from a diesel Euro V engine using diesel/biodiesel blends in Brazil.

The Brazilian legislation does not establish limits or methodology for the measurement of aldehydes in the exhaust of heavy diesel engines. No conclusive studies on aldehyde emissions by such engines have been found in the literature available. This work measured the aldehyde emissions from a P7 diesel cycle engine (EURO V), which was tested on an engine test bench according to ETC (European Transient Cycle) and ESC (European Stationary Cycle) cycles using fuels with 5, 7 and 20% v/v of biodiesel and 10 and 500 ppm of sulphur. The results showed that biodiesel participation in the mixture did not significantly affect the aldehyde emissions of the tested engine and that the emission level generated in the ETC cycle is higher than that obtained with the ESC cycle. The diesel content in the blend was weakly and negatively correlated with the pollutant emissions, and the inverse pattern was observed for biodiesel. This finding indicates that an increase in biodiesel content causes a slight increase in pollutant emissions. Regarding the sulphur content, positive correlations between the sulphur content and particulate matter, NOx, CO and total hydrocarbon emissions were observed. When comparing the test cycles, the results were significantly different, with higher values for the ETC cycle.

Determination of size-segregated elements in diesel-biodiesel blend exhaust emissions.

This study was based on the determination of metals in particulate matter emitted by a typical diesel engine used by busses and trucks in Brazil. Emissions were sampled using a cascade impactor, and the engine was operated using diesel with 5% (B5), 10% (B10), 15% (B15), and 20% (B20) of biodiesel. The particulate matter was stratified in different sizes, i.e., 18, 5.6, 3.2, 1.8, 1.0, 0.560, 0.320, 0.180, 0.100, and 0.056 µm. Cd, Co, Cr, Cu, Mn, Mo, Ni, Pb, V, and Zn with concentrations within 10 to 1000 ng m-3 were determined. The results indicate a trend in the prevalence of lead, nickel, and chromium in coarse particles and nanoparticles in all blends of fuels. By comparing the results of B5, B10, B15, and B20 fuels, we can confirm that the addition of biodiesel to diesel promotes a reduction of emissions, and by comparing the behavior of the concentration of all elements analyzed, emissions by B10 and B15 fuels are similar, while B5 and B20 suffer significant changes during the process of combustion. Multivariate statistical analysis was used, and it indicates possible sources in three clusters, one for Ni, other for Cr-Mn, and the last one for other metals.

Emissão de gases do efeito estufa de um aterro sanitário no Rio de Janeiro / Greenhouse gases emissions from a landfill in Rio de Janeiro

RESUMO A emissão de metano (CH4) e dióxido de carbono (CO2) em aterros sanitários representa uma das mais importantes fontes de gases de efeito estufa em regiões metropolitanas. O presente trabalho quantificou a taxa de emissão de gases do efeito estufa (GEEs) pela camada de cobertura intermediária do aterro sanitário de Seropédica, Rio de Janeiro, Brasil, assim como a concentração desses gases na atmosfera acima das células do aterro. Um total de 21 amostras na camada de cobertura e 31 na atmosfera acima do aterro foi coletado. Foram utilizadas duas câmaras de fluxo de 0,66 m2 de área e 33,2 L de volume, e amostras foram retiradas com seringas de polipropileno de 60 mL em intervalos de 5 minutos, durante 15 minutos. As amostras foram coletadas em locais com e sem fissura na camada de cobertura intermediária. A análise das amostras foi feita por cromatografia de fase gasosa, por múltiplos detectores. As taxas de emissão dos GEEs observadas variaram entre 0,1 e 575,0 g m-2 dia-1 para CH4 e entre 0,1 e 316,0 g m-2 dia-1 para CO2. As concentrações no ar ambiente variaram entre 3,5 e 150,0 ppm e entre 333 e 655 ppm, para CH4 e CO2, respectivamente. As maiores emissões foram constatadas nos pontos que continham as maiores fissuras no momento da coleta.

ABSTRACT The emission of methane (CH4) and carbon dioxide (CO2) from landfills is one of the most important sources of greenhouse gases in metropolitan areas. This study quantified the emission rate of greenhouse gases (GHGs) by the intermediate cover layer of Seropédica landfill, in Rio de Janeiro, Brazil, as well as the concentration of these gases in the atmosphere above the landfill cells. A total of 21 samples from the cover layer and 31 samples from the atmosphere above the landfill was collected. Two flow chambers with 0.66 m2 and 33.2 L were used, and the samples were collected with 60 mL polypropylene syringes at five-minute intervals, for 15 minutes. The samples were collected in areas with and without cracks in the intermediate cover layer. Sample analysis was performed by gas chromatography, by multiple detectors. GHGs emission rates varied from 0.1 to 575.0 g m-2 day-1 for CH4 and 0.1 to 316.0 g m-2 day-1 for CO2. The ambient air concentrations ranged from 3.5 to 150.0 ppm and 333 to 655 ppm for CH4 and CO2, respectively. Higher emissions were found in areas containing the larger cracks at the time of collection.

Isoprene Emissions and Ozone Formation in Urban Conditions: A Case Study in the City of Rio de Janeiro.

The potential role of isoprene oxidative processes, as well as the possible impact of air pollution on isoprene emissions, are more important in tropical cities, surrounded by rainforests. In this study, the contribution of isoprene to ozone formation was determined considering different scenarios, mainly volatile organic compounds/NO x (VOC/NO x ) ratios, and typical atmospheric conditions for the city of Rio de Janeiro, where more than 36% of the urbanized area is covered by vegetation. Ozone isopleths and incremental reactivity coefficients (IR) were evaluated to understand the direct contribution of isoprene to ground-level ozone formation and the negative impact of anthropogenic NO x emissions on the natural atmospheric balance. Although isoprene accounted for only 2.7% of the total VOC mass, excluding the isoprene concentration from the model reduced the maximum ozone value by 14.1%. The calculated IR coefficient (grams of O3 formed per gram of added isoprene) was 2.2 for a VOC/NO x ratio of 8.86.

BTEX Emissions from the Largest Landfill in Operation in Rio de Janeiro, Brazil.

The emission rates and the ambient air concentrations of benzene, toluene, ethyl benzene and xylenes (BTEX) were measured over the intermediate cover layer and atmosphere of the Seropédica landfill, Rio de Janeiro, Brazil. BTEX were sampled using coconut shell charcoal cartridges, followed by extraction with dichloromethane and analysis by gas chromatography with mass spectrometry. Thirteen samples were collected in areas with and without cracks in the cover layer, and six samples were collected from the ambient air. The average emission rates were 11.7, 492.2, 153.7, 67.2, and 21.7 µg m- 2 day- 1, respectively, for benzene, toluene, ethyl benzene, m + p-xylenes and o-xylene. No benzene concentrations above the detection limit were observed in ambient air samples. The average concentrations of toluene, ethyl benzene, m + p-xylenes and o-xylene in ambient air samples were 2.14, 1.35, 0.49 and 0.08 µg m- 3, respectively. Higher emissions were found in locations containing larger cracks during the collection.

Avaliação ambiental de BTEX (benzeno, tolueno, etilbenzeno, xilenos) e biomarcadores de genotoxicidade em trabalhadores de postos de combustíveis / Environmental assessment of BTEX (benzene, toluene, ethylbenzene, xylenes) and biomarkers of genotoxicity in gas stations workers

Resumo Introdução: trabalhadores de postos de combustíveis estão expostos às diversas substâncias químicas presentes no ambiente de trabalho, destacando-se entre elas o benzeno, devido às suas propriedades carcinogênicas. Objetivo: avaliar os danos genotóxicos relacionados à exposição ocupacional ao BTEX (benzeno, tolueno, etilbenzeno, xilenos) em trabalhadores de cinco postos de combustíveis do município do Rio de Janeiro, RJ. Metodologia: foram analisadas concentrações de BTEX no ar; atividades das enzimas catalase e glutationa S-transferase; e ensaio cometa em amostras de sangue total de 97 trabalhadores. Resultados: as concentrações de BTEX estavam dentro dos valores preconizados pela NR 15, incluindo Anexo 13-A. Entretanto, uma oscilação nos resultados de ensaio cometa foi observada entre os trabalhadores dos diferentes postos de combustíveis, principalmente em trabalhadores de postos com menores concentrações de benzeno. Discussão: esse resultado está de acordo com a literatura científica atual, que indica uma curva dose-resposta supralinear para o benzeno, observando-se em baixas concentrações um aumento não linear do risco de leucemia, provavelmente relacionado à maior metabolização do benzeno e à maior produção de seus metabólitos tóxicos nessas concentrações. Conclusão: os resultados deste estudo sugerem que a exposição ao BTEX, mesmo em baixas concentrações, contribui para o risco genotóxico à saúde humana.

Abstract Introduction: gas station workers are exposed to several chemicals in their workplace, highlighting benzene, due to its carcinogenic properties. Objective: to assess the genotoxic damage related to occupational exposure to BTEX (benzene, toluene, ethylbenzene, xylenes) in workers of five gas stations in Rio de Janeiro, RJ. Methods: analysis of BTEX concentrations in the air were carried out; as well as activities of catalase and glutathione S-transferase; and comet assay in whole blood samples of 97 workers. Results: BTEX levels were within the Brazilian threshold levels recommended by the NR 15, including Annex 13-A. However, an oscillation of the comet assay results was observed among workers of different gas stations, mainly in workers from gas stations with lower concentrations of benzene. Discussion: this result is in accordance with the current international scientific literature that indicates a supralinear exposure-response curve for benzene. In lower concentrations we could observe a high non-linear risk of leukemia, probably due to a greater benzene metabolism and a higher production of its toxic metabolites. Conclusion: the results of this study suggest that exposure to BTEX, even in low concentrations, contributes to genotoxic risk to human health.

The relationship between solvent use and BTEX concentrations in occupational environments.

Indoor air quality is an increasing concern; it causes significant damage to health because it is recycled in confined environments for extended periods of time. Among the pollutants found in these environments, benzene, toluene, ethylbenzene, and xylenes (BTEX) are known for their potential toxic, mutagenic, and carcinogenic effects. This study monitored the BTEX concentrations in paint, carpentry, and varnish workplaces and evaluated the potential to cause adverse health effects on workers in these environments. Twenty samples were collected in workplaces, 20 samples were collected outside the area, and eight samples were taken of the products used. Samples were collected using coconut shell cartridges, and chemical analyses were performed by gas chromatography with mass spectrometry. Toluene presented higher indoor concentrations and indoor and outdoor ratios, indicating that the paint and varnish workplaces had significant BTEX sources. The highest benzene and toluene concentrations were obtained from the paint workshop, and higher concentrations of ethylbenzene and xylenes were obtained in the varnish workshop. The highest non-carcinogenic risks were obtained for m + p-xylenes in the varnish work place, and the second highest non-carcinogenic risk was also determined for the same workshop.

Kinetic and mechanistic reactivity. Isoprene impact on ozone levels in an urban area near Tijuca Forest, Rio de Janeiro.

Volatile organic compounds (VOCs) play a central role in atmospheric chemistry. In this work, the kinetic and mechanistic reactivities of VOCs are analyzed, and the contribution of the organic compounds emitted by anthropogenic and natural sources is estimated. VOCs react with hydroxyl radicals and other photochemical oxidants, such as ozone and nitrate radicals, which cause the conversion of NO to NO2 in various potential reaction paths, including photolysis, to form oxygen atoms, which generate ozone. The kinetic reactivity was evaluated based on the reaction coefficients for hydroxyl radicals with VOCs. The mechanistic reactivity was estimated using a detailed mechanism and the incremental reactivity scale that Carter proposed. Different scenarios were proposed and discussed, and a minimum set of compounds, which may describe the tropospheric reactivity in the studied area, was determined. The role of isoprene was analyzed in terms of its contribution to ozone formation.

Volatile Organic Compounds in the Atmosphere of the Botanical Garden of the City of Rio de Janeiro: A Preliminary Study.

Volatile organic compounds (VOCs) play a central role in atmospheric chemistry. In this work, VOCs in the Botanical Garden of Rio de Janeiro were determined using the TO-15 Method. The park occupies 1,370,000 m2 in the southern area of the city and is next to the Tijuca Forest, which is considered the largest secondary urban forest in the world. The total VOC concentrations ranged from 43.52 to 168.75 µg m-3, depending on the sampling site and dates. In terms of concentration isoprene represented 4 %-14 % of the total VOC masses. The results suggested that the differences in biomass, distance from the street and activities within the park affected the concentrations of VOCs. The ratios of isoprene/aromatic compounds were higher than those determined in other areas of the city, confirming that the atmosphere of this green area has the contribution of other sources. Kinetic and mechanistic reactivities were also evaluated.

Role of carbonyls and aromatics in the formation of tropospheric ozone in Rio de Janeiro, Brazil.

The ozone in Rio de Janeiro has been in violation of national air quality standards. Among all of the monitoring stations, the Bangu neighbourhood has the most violations of the national standard of 160 µg m(-3) for the years 2012 and 2013. This study evaluated the reactivity of the carbonyls and aromatics in the tropospheric ozone formation processes. The samples were collected between July and October of 2013. Carbonyls were sampled using SiO2 cartridges coated with C18 and impregnated with 2,4-dinitrophenylhydrazine and were analysed by HPLC. Activated carbon cartridges and GC/MS were used to measure the concentration of monoaromatic hydrocarbons. An air quality monitoring station provided the concentrations of the criteria pollutants and the meteorological parameters. Cluster analysis and a Pearson correlation matrix were used to determine the formation of groups and the correlation of the variables. The evaluation of the volatile organic compounds (VOC) reaction with OH radicals and the MIR scale was used to extrapolate the reactivity of VOCs to the ozone formation. The average concentrations obtained were 19.7 and 51.9 µg m(-3) for formaldehyde and acetaldehyde, respectively. The mean concentrations obtained for aromatics were 1.5, 6.7, 1.5, 2.6 and 1.6 µg m(-3) for benzene, toluene, ethyl benzene, m+p-xylene and o-xylene, respectively. The cluster analysis indicated the presence of three similar groups, with one formed by gaseous criteria pollutants, another formed by the meteorological parameters, ozone and fine particles, and the last group formed by the aromatics. For the two reactivity scales evaluated, acetaldehyde and toluene were the main ozone precursors.

BTEX no interior de salas de aula de spinning / BTEX inside a spinning classroom

Atividades Físicas realizadas em ambientes fechados estão se tornando mais frequente. Estudos têm mostrado que as concentrações de poluentes em ambientes interiores são sempre maiores do que em ambiente abertos. Em locais fechados, onde são realizados exercícios de forma regular, não existe a preocupação com a qualidade do ar, principalmente quando estão sendo realizadas atividades aeróbicas. Neste estudo, foram medidas concentrações de BTEX em uma sala de spinning e as concentrações obtidas foram maiores do que as encontradas em ambientes ao ar livre. No entanto, uma atividade de pintura realizada na sala de spinning gerou concentrações elevadas de todos os BTEX , e, em particular, o tolueno teve concentrações muito maiores. No dia seguinte a realização da pintura, as concentrações de todos os BTEX tinham aumentado significativamente e a concentração de tolueno foi de 274.9 µg/m³. Após a pintura na sala de spinning, o aumento foi de 91% para o benzeno, 907% para o tolueno, 182% para o etilbenzeno, 121% para o m+p-xileno e de 128% para o o-xileno.

Indoors Physical Activities are becoming more frequent. Studies have shown that pollutants concentrations in indoor environments are always greater than in open environments. In indoor locations where regular exercise are performed, there is no concern about air quality, principally when aerobic physical activity are performed. BTEX concentrations in a spinning classroom were measured in this study and were higher than those obtained in an outdoor environment. However, a painting activity of the room revealed that all BTEX concentrations, and in particular Toluene, become much greater. In the day after, the paint concentration of all BTEX increased significantly and the concentration of toluene was 274.9 µg/m³. The BTEX concentration increased after all room was painted, and this increase was from 91% to benzene, 907% for toluene, 182% to ethylbenzene, 121% for m+p-xylene and 128% for o-xylene.

Ozone precursors for the São Paulo Metropolitan Area.

Ozone represents the main atmospheric pollutant in the São Paulo Metropolitan Area (SPMA). In this region, its concentration exceeds the national air quality standards for several days out of the year. Ozone is a secondary pollutant and is a product of VOCs, NO(x), and sunlight. Thus, it is very difficult to elaborate efficient strategies for its reduction. Computational simulations may provide an interesting alternative to evaluate the many factors that affect ozone formation. In this study, the trajectory model OZIPR was used together with the SAPRC chemical mechanism to determine the incremental reactivity scale for VOCs in the SPMA. VOC input data were obtained from two campaigns that were performed in the studied area in 2006. Values for CO, NO(x), and meteorological parameters were obtained by automatic monitors. Five base-cases were created to verify the variation in maximum ozone concentration and thus determine the ozone formation potential of each VOC. NO(x) and VOC emissions were independently and simultaneously reduced by 5, 10, 20, and 30% to verify variations in ozone formation. With the simulator output data, ozone isopleths charts were generated for the city of São Paulo. Analysis of the obtained results shows that the most frequent compounds found among the ten main ozone precursors in São Paulo, using the reactivity scales created from the five base-cases, were: formaldehyde, acetaldehyde, propene, isoprene, cis-2-butene, and trans-2-butene, with formaldehyde being always the main ozone precursor compound. The simulations also show that an efficient strategy to decrease ozone concentrations in the SPMA would be to reduce total VOC emissions. The same strategy is not possible for NO(x), as the reduction of these pollutants would increase ozone concentrations.

Emissões de poluentes não legislados por biodiesel / Emissions of non-criteria biodiesel pollutants

Seguindo uma tendência mundial, especialmente na Europa, o governo brasileiro autorizou a partir de 2005 o uso de 2% de biodiesel por veículos pesados. Este nível foi incrementado para 3% em 2008, quando estará autorizado o uso de 5% de biodiesel, que será definitivamente implementado pela frota em 2013. Diversos estudos identificaram que o biodiesel emite menores níveis de dióxido de carbono, óxidos de enxofre e material particulado. Entretanto, algumas classes de poluentes, como os compostos orgânicos voláteis (COVs) são carentes de dados. As emissões destes compostos não pode ser medida pelos equipamentos comerciais disponíveis usados pelas agências ambientais, que apenas quantificam os hidrocarbonetos de forma totalizada. Este trabalho fez uma avaliação das emissões de poluentes não legislados, como carbonilas, hidrocarbonetos aromáticos e policíclicos aromáticos e mercaptanas. Os testes foram conduzidos em dois motores diesel de seis cilindros, dentre os mais usados pelos ônibus urbanos no Brasil. Os teores de biodiesel testados foram 2, 5, 10 e 20% v/v de biodiesel (B2, B5, B10 e B20), e também com diesel puro (D). Os resultados indicaram um aumento nas emissões de carbonilas, com exceção do benzaldeído. As emissões de hidrocarbonetos monoaromáticos tiveram uma redução média de 4,7% para B2, 8,7% para B5 e 21,5% para B20. Para os hidrocarbonetos policíclicos aromáticos obteve-se reduções para B2, B5 e B20 de 2,7%, 6,3% e 17,2%, respectivamente. As emissões de mercaptanas também apresentaram redução em função do aumento do teor de biodiesel.

Following a worldwide trend, mainly in Europe, Brazilian government authorized since 2005 the use of 2% of biodiesel by heavy duty vehicles. This level was increased to 3% in 2008, when it will be authorized the use of 5% of biodiesel, which will be implemented in all of our fleet of vehicles in 2013. Several studies identified that biodiesel emits lower levels of carbon dioxide, sulfur dioxides and particulate matter. However, some classes of pollutants as volatile organic compounds (VOCs) lack of this kind of data. The emissions of these pollutants can not be identified by the commercial on-line equipments used by the environmental agencies; they only analyze the total quantities of these compounds. This study has done an evaluation of some non-criteria pollutants, as carbonyls, monoaromatic and polycyclic aromatic hydrocarbons, and mercaptans. Emission tests were done using two six cylinders diesel engines, commonly used by the urban buses in Brazil, that were tested with 2, 5, 10, and 20% v/v of biodiesel (B2, B5, B10, and B20), as well as with plain diesel (D). The results indicated an increase on the carbonyls emissions, with exception of benzaldehyde. The monoaromatic hydrocarbon emissions exhibit a reduction of 4.7% for B2, 8.7% for B5, and 21.5% for B20. For the polycyclic aromatic compounds the emissions reduction for B2, B5, and B20 were 2.7%, 6.3%, and 17.2%, respectively. The emissions of mercaptans also exhibit a reduction with the biodiesel content.