Sergio Machado Corrêa

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.

Genotoxicity of polycyclic aromatic hydrocarbons and nitro-derived in respirable airborne particulate matter collected from urban areas of Rio de Janeiro (Brazil).

Air pollution toxic effects are mainly attributed to small inhalable particulates with an aerodynamic diameter of less than 2.5 µm (PM 2.5). Our objective was to investigate mutagenic and clastogenic activity in PM samples collected in Rio de Janeiro. Samples were collected using a high-volume sampler at three sites: with low traffic and (2) and (3) with a heavy traffic. Six polycyclic aromatic hydrocarbons (PAHs) were quantified by gas chromatography/mass spectrometry (GC/MS). Salmonella typhimurium TA98 and the derivative strains YG1021 and YG1024 were used in mutagenicity assays in the presence of organic extracts (10–50 µg/ plate) with and without exogenous metabolization. Allium cepa test was performed to evaluate possible cytotoxic and clastogenic activities. The highest PM 2.5 µm (132.73 µm/m3) and PAH values (1.22 ng/m3 for benzo(a)pyrene) were detected at site 3. High mutagenic frameshift responses in absence and presence of metabolic activation were detected at site 3. The participation of nitroarenes and dinitroarenes was detected in the total mutagenicity of the extracts studied. The cytotoxic effect and the abnormalities detected by Allium cepa test can be attributed to the PAH nitroderivatives in the organic extracts. Evaluation of the genotoxicity of urban airborne particulate matter is important as a basis for decision making by regulatory authorities.

Understanding Ozone Concentrations During Weekdays and Weekends in the Urban Area of the City of Rio de Janeiro

In different cities around the world, higher ozone concentrations are observed during weekends for various reasons. This study aims to determine the causes of this effect in the city of Rio de Janeiro based on measurements obtained at three automatic air quality monitoring stations in the Bangu, Campo Grande and Iraja neighborhoods between 2012 and 2013. Variations in the solar radiation and hourly carbon monoxide, nitrogen oxides, non-methane hydrocarbons, ozone and particulate matter concentrations were determined. The Bangu station showed the lowest ozone concentration differences between the weekdays and weekends (8.9%) and recorded the highest ozone concentrations and largest number of exceedances. The low ozone consumption by nitrogen oxide resulted in the high ozone concentrations at the Bangu station. In addition, the volatile organic compounds (VOC)/nitrogen oxides (NOx) ratio for this station was evaluated for each day of the week between 6 and 9 AM, and the observed VOC/NOx ratios were higher at the Campo Grande and Iraja stations. We concluded that the weekend effect occurred at all three of the evaluated stations, with greater intensity at the Campo Grande and Iraja stations. The main cause of this weekend effect is the greater reductions in NO emissions over the weekends, which increase the VOC/NOx ratio.

A two-year monitoring program of aromatic hydrocarbons in Rio de Janeiro downtown area

Benzene, toluene, ethylbenzene, m+p+o-xylene (BTEX) and two trimethylbenzenes (BTEXT) were monitored in Rio de Janeiro downtown area during 2004 and 2005. Some criteria pollutants and meteorological parameters were also determined in order to assess the main data correlations. 94 samples were collected, using activated charcoal cartridges, between 9:00 am and 3:00 pm. The mean concentrations obtained were: 14.5, 22.8, 9.19, 19.3, 8.5, 10.4 and 12.1 µg m-3 for benzene, toluene, ethylbenzene, m+p-xylene, o-xylene, 1,2,3-trimethylbenzene and 1,3,5-trimethylbenzene, respectively. These values are similar to mean concentrations obtained in the Brazilian cities of Porto Alegre, Volta Redonda and Sao Paulo, which use the same type of fuel. Multivariate analyses showed that individual BTEXT are emitted by the same source and are not well correlated with other primary pollutants. These results may be due to the contribution of evaporative losses of the BTEXT and to the formation of secondary volatile organic compounds in the atmosphere.

Volatile organic compound emissions from a landfill, plume dispersion and the tropospheric ozone modeling

. Um modelo de dispersao Gaussiano foi usado para avaliar o transporte dos poluentes e valores de 525 μg m -3 para VOC foram encontrados a ca. 500 m do aterro. As emissoes tambem foram compiladas com dados meteorologicos usando o modelo de trajetorias OZIPR (Ozone Isopleth Package for Research) acoplado ao modelo quimico SAPRC (Statewide Air Pollution Research Center) para avaliar o impacto na formacao de ozonio troposferico. Os resultados indicaram um aumento de mais de 1000% nos niveis de ozonio comparados com valores da regiao metropolitana do Rio de Janeiro. Os resultados indicaram que e necessaria uma maior atencao dos orgaos governamentais no gerenciamento dos residuos solidos no Brasil. This work evaluated the volatile organic compound (VOC) emissions by a landfill located in Niteroi City, RJ, Brazil. Twenty six samples were collected in 2009 using a 30 L cylindrical polyvinyl chloride (PVC) flux chamber. The results indicated an elevated emission of 1980 kg km -2 h -1 . A Gaussian plume dispersion model was used to evaluate the transport of pollutants and values of 525 μg m -3 for VOC were found at ca. 500 m from the landfill. The emissions were also compiled with meteorological data, using the OZIPR (Ozone Isopleth Package for Research) trajectory model coupled with SAPRC (Statewide Air Pollution Research Center) chemical mechanism to demonstrate the impact on tropospheric ozone. The results indicated a 1000% increase in ozone in the region of the landfill when compared to the ozone values for the metropolitan region of Rio de Janeiro. The results show that it is necessary greater attention to the political management of municipal solid waste in Brazil.

Measurements of emissions from motorcycles and modeling its impact on air quality

The increase in the number of motorcycles in large Brazilian cities is due to several factors such as traffic, low cost, mobility, few parking lots and the low efficiency of public transportation, becoming an important factor in air quality deterioration. In this context, vehicle emissions monitoring is essential to understand the contribution to air pollution as a whole. In this scenario, the emissions were sampled on a motorcycle dynamometer test bench and analyzed by gas chromatography and on-line analyzers according to the EC/97/24 standard (European Commission). Emissions from motorcycles using commercial gasoline (with 22% of ethanol) were used in combination with meteorological data and ambient air pollutants for Rio de Janeiro City (Brazil) during the Winter of 2011, using the trajectory model OZIPR (Ozone Isopleth Package for Research) and the chemical model SAPRC99 (State-wide Air Pollution Research Centre) to assess the impact on the ozone formation in the troposphere of Rio de Janeiro for the next several years. The results indicate that ozone levels will exceed the established limits by national legislation within three years. The study also showed that pollutant emission rates stay in agreement with emissions recommended by the Brazilian legislation for all phases. The increase in ozone concentration occurs due to high emissions of reactive volatile organic compounds in an atmosphere with high levels of nitrogen oxides (NOx). Given this scenario, additional measures are necessary to manage emissions from mobile sources in the future.

PRINCIPAIS CARBONILAS NO AR DE LOCAIS PÚBLICOS NO RIO DE JANEIRO

An air quality evaluation of indoor environments with focus on lower carbonyls was carried out in 50 public places using TO-11A methodology. Formaldehyde levels (ranging from 12.5 to 1034 mg m-3) were above the threshold limit in 49 of 50 analyzed samples while acetaldehyde (ranging from 5.2 to 840 mg m-3) and acetone (ranging from 5.5 to 4839 mg m-3) were respectively bellow the limits of OSHA and NIOSH in all samples. However all samples were bellow the threshold limits suggested by the Brazilian legislation - NR-15. A correlation study between the carbonyls and temperature and humidity was also done.

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.

Avaliação da eficiência do método TO-15 para determinação de compostos orgânicos voláteis em condições típicas de ambiente urbano

detection limit of ≤0.2 ng for all target compounds, replicate precision for a calibration standard and ambient samples within 20%. The stability of the target compounds during storage of sampled air in canisters was also evaluated at atmospheric pressure and relative humidity of 50%. Results show that, in the sampling conditions, compounds are not stable for more than a week. For validation experiments, samples were collected at the entrance of Tijuca National Park, located at the city of Rio de Janeiro. Isoprene was selected as a marker of biogenic emissions, and aromatic compounds were selected as markers of anthropogenic emissions, primarily vehicular emissions. Then, samples were collected in Saens Pena Square, a central area in the Tijuca District, in the northern part of the city, approximately 10 km from the entrance of Tijuca National Park. Volatile organic compounds were determined and the results were compared with previous data obtained in the same local using other methods.

BTEX no interior de salas de aula de spinning

Atividades Fisicas realizadas em ambientes fechados estao se tornando mais frequente. Estudos tem mostrado que as concentracoes de poluentes em ambientes interiores sao sempre maiores do que em ambiente abertos. Em locais fechados, onde sao realizados exercicios de forma regular, nao existe a preocupacao com a qualidade do ar, principalmente quando estao sendo realizadas atividades aerobicas. Neste estudo, foram medidas concentracoes de BTEX em uma sala de spinning e as concentracoes obtidas foram maiores do que as encontradas em ambientes ao ar livre. No entanto, uma atividade de pintura realizada na sala de spinning gerou concentracoes elevadas de todos os BTEX , e, em particular, o tolueno teve concentracoes muito maiores. No dia seguinte a realizacao da pintura, as concentracoes de todos os BTEX tinham aumentado significativamente e a concentracao de tolueno foi de 274.9 µg/m³. Apos 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.